ICPTT 2013: Trenchless Technology

Since floods and geological disasters occur frequently in the Loess Plateau, oil and gas pipeline projects are vulnerable to the threat of many disasters (including floods, landslides, and collapse) which seriously affect the safe operation of pipelines. In this paper, the simplified Bishop method and the slope stability calculation program "STAB-95" from the Beijing Hydraulic Research Institute are applied to conduct stability calculations of the loess natural slopes and artificial fill slopes with different slope height, slope ratio, water contents and filling. Meanwhile, a detailed analysis of the correlation between stability safety factor of a slope and slope height, slope ratio, etc. is conducted combining with the calculated results, after which some comprehensive treatment measures for the slopes of Loess Plateau are provided.

Water supply network is a complex urban network. It is multi-source and undirected. It is closely related to a city's prosperity index. However, tens of thousands of cities in the world are suffering harassment from water pipe burst. The accidents have seriously affected the productive and living activities of urban residents while accompanied by the loss of the property, casualties, etc. The problems that we have always been concerned with are, when an accident occurs, how to get to the scene of the accident the first time in the fastest way, and how to properly deal with the scene by applying the most economical, effective, and rapid solution. In this paper, based on the actual situation of urban water supply networks, we get the information of burst pipeline, the valve closing information, the sphere of influence of the valve closing, pipe network facilities affected by closing valves and so on with the technology of GIS network analysis. In this case, we analyzed the values of processing results as well as whether the valve should be closed to get the most economical, effective solution. Based on ArcEngine, we have applied this solution to the actual project. We can also outreach this program to do the processing and analysis of all kinds of urban pressure pipe networks.

A method of fuzzy clustering analysis was proposed to evaluate the structural safety. Based on the study of the municipal tunnel behavior, this paper used the numerical simulation method to analyze the present condition of the tunnel so as to obtain the present behavior and the influence law of the municipal tunnel. Four key factors were considered during the course of analysis: the reinforcement corrosion, the concrete crack, the tunnel water leakage and the soil liquid-plastic state. Then, the fuzzy clustering analysis method was used to evaluate the safety of the tunnel. Moreover, taking a typical electric power tunnel as an example and using the fuzzy clustering analysis to synthetically evaluate the safety grade, the results showed that the four factors above had a different impact on the safety of the tunnel. Through the results, we established a tunnel evaluation theory system to evaluate the structural reliability. The theory and method had important practical value to the tunnel engineering.

Urban underground pipelines are an important part of urban public infrastructure and the lifeline of cities. Information management of urban underground pipelines also was important to urban underground pipeline managers. This paper proposes an improved QR-tree indexing mechanism for underground pipeline data management which divides the urban area into multi-level grid. The R-tree index was established by each grid that has the only code to achieve fast retrieval of pipeline data.

A pipeline protection retaining wall, as a main type of hydraulic protection projects, is sometimes destroyed by flood scour, causing local or overall deformation and the acceleration of destruction of hydraulic retaining walls along the river bend. It poses a great threat to the normal operation of a pipeline. Based on the structure characteristics and the damage form of hydraulic retaining walls in long distance transportation pipelines along river bend under flood scouring, this article presents a numerical model of the retaining wall and analyzes the deformation characteristics in flood period, especially the influence of riverbed lateral widening depth, the water level changing and the flow rate of flood. The results of the study show that the silt shear failure when the flood scouring force is greater than silt shear force causes the basal silt incision and scouring. There is a positive correlation between the deformation characteristics of a retaining wall and the dropping amplitude of flood water level. Compared with the rising flood period, the retaining wall is more likely to overturn. Lateral widening depth and the falling amplitude of flood are the main parameters to the anti-overturning stability of wall. Improving the retaining wall drainage ability and strengthening the foundation protection of retaining wall are effective measures to alleviate the deformation of hydraulic retaining wall.

The modified minimum night flow method, which is based on drainage system hydraulic model, was developed for infiltration estimation of a pump-lifting drainage system. With the help of the function of "storage volume" of the network hydraulic model, consecutive sewage discharge curves were produced for pump-lifting systems for which outflows are usually intermittent with pumps on/off, and no minimum night flow existed. Thereby, the modified minimum night flow method could be applied to pump-lifting systems' infiltration estimation. A case study was carried out for a combined sewer system in Hefei, China. Infiltration values of the case were evaluated. Moreover, the infiltrations value was compared with those obtained from the water consumption method. Results indicate the modified minimum night flow method is an effective tool for estimating infiltration of pump-lifting drainage systems.

With the rapid development of the economy, the demands for oil and gas are further increased. A pipeline system is the main form of transportation for natural gas. The high-strength pipeline steel will become the preferred material for modern natural gas transmission pipelines. It is well known that nickel is an important element in the high-strength pipeline steel. In this paper, a novel spectrophotometric method was described for determination of nickel in high-strength pipeline steel. The method was based on the color reaction between nickel and dimethylglyoxime, which was favored in an alkaline medium, producing a red compound in the presence of ammonium persulfate as an oxidant. Under the optimum reaction conditions, the absorption value was proportional to the concentration of nickel in the range of 0.076~0.66% (R² = 0.9999), and the relative standard deviation was less than 3.0% (n=5). The proposed method was applied successfully to determine nickel in X80 grade pipeline steels and X70 grade pipeline steels, respectively.

With the improvement of excavation requirements in domestic municipal pipeline engineering, pipe jacking methods are applied in municipal pipeline engineering more frequently. Utilizing ground penetrating radar to detect underground cavity and non-dense areas which are caused by soil disturbance in construction is becoming an important means of construction quality inspection and prediction technology of post-construction settlement. Based on the sewage pipeline project in Shang Hang Road, Feng Wei newly-developed area, Xi'an, we detect the size and distribution of construction caves - which are upper and both sides of the pipes - by using the method of inspecting ground and pipe with ground penetrating radar and on-site observation. The paper presents some detection methods and preliminary solutions of non-dense sand layer caused by construction process in floodplain sand layers of non-collapsible loess regions, and summarizes detection technology and precautions of pipe jacking construction in sand layer.

The characteristics of a piezoelectric ceramic chip (PZT) are sensitivity on the structural initial damage, strong immunity to the outside environment, and the double effect (sensing and drive). It is significant to identify structural material damage by the piezoelectric impedance method. This paper summarizes and analyses the existing application scope and evaluating precision of the evaluation index of structural damage based on the piezoelectric impedance method and presents and verifies a pipeline structure health assessment evaluation index. The result shows that the evaluation index based on the piezoelectric impedance method is feasible for timely and accurate identification of pipeline structure material damage, but remains with many difficulties and problems to be solved.

Water pipeline networks make up vital infrastructures throughout the world. Since water pipelines operate under high pressure, their failure can cause severe damage to human health and property. In this study, the water pipeline network of a district in Tehran was modeled using the Finite Element Method (FEM). Also, different soil-pipe conditions were considered and nonlinear time-history analysis was performed via seismic scaled records of Near-Fault (NF) and Far-Fault (FF) earthquakes. Furthermore,theOptimal Sensor Placement (OSP) procedure was done in which a genetic algorithm (GA) was selected to act as the solution of the optimization formulation. Only bolted-gland joints in the modeled network were considered for OSP due to their vulnerability against seismic loads. Unlike the common algorithms that employ modal analysis results, the author proposed a novel numerical approach for OSP that utilizes nonlinear time-history analysis results as an exact seismic response. The results showed that there is a significant difference between the obtained OSP results of NF and FF earthquakes.

River-crossing pipelines could be eroded by flood crushing, so that part of the pipeline would be exposed and subject to a considerable flood force. In this paper, mechanical analysis models of exposed and unexposed parts of the pipeline under flood are established in considering the inner pressure of pipeline and the pipeline-soil interaction. The mechanical state of a pipeline is calculated using the global analytical searching method, and entropy (based on strain energy of zones) is obtained simultaneously. Besides, the variation of strain energy entropy with flood velocity is achieved. The study shows that the variation of strain energy entropy versus flood force could better reflect the yield feature of the whole pipeline. The curve of strain energy entropy can be easily divided into three stages corresponding to the non-yield stage, the partial yield stage and the failure stage respectively, which indicate the yield or failure state of pipeline clearly. The boundaries of stages are significantly influenced by diameter, thickness, and exposed length of pipeline, and are less affected by inner pressure and depth of pipeline, relatively. In addition, the entropy identification could be used as a new method to identify the failure state of pipeline under flood.

The accidents of buried pipeline leaks occur occasionally in oil deposits. The leak of oil and gas pipeline downtown brings especially great influence and immeasurable loss to urban safety and oil field production. In order to provide technical support for rapid rescue of buried pipeline sudden leak accident, the Technology Inspection Center of ShengLi Oilfield has actively carried out research and developed a set of combined leak testing technology which can detect and discriminate the pipeline leak point quickly. The method has combined transient electromagnetic testing, guided wave testing, electromagnetic testing, stray current testing, acoustic emission testing, magnetic memory testing, non-metal pipeline testing, gas concentration testing, infrared temperature testing, etc. It has effectively avoided the problems of the intensive distribution of underground pipelines and too much of the signal interference source. It has solved the problem of locating the pipeline leak point underground and under the hardening urban pavement. This paper introduces the principle, characteristics and application of the technology with examples.

In order to study the fundamental principles of the acoustic leak detection method for natural gas pipelines, this method is applied in the laboratory and in field experiments. First, the experiments are made in the laboratory and the leakage signal characteristics are concluded. Then, the field experiments are accomplished to acquire leakage signals which will be processed by the time-domain analysis, the frequency-domain analysis and the joint time-frequency analysis together to extract the characteristics. Finally, the extracted acoustic characteristics are applied to detect the leakage of the long-distance pipeline. The results show that the acoustic characteristics extracted by wavelet transform can be propagated long distance. Therefore, the acoustic leak detection method can be applied to long-distance natural gas pipelines.

Reducing the inlet water pressure of the district metering area (DMA) can be achieved by fixed outlet pressure control and intelligent flow-modulated pressure control, respectively, to reduce leakage in water distribution systems. In order to weaken temperature factor influence on the benefit analysis from pressure management field study, a new methodology is proposed in this paper which is based on theories, such as regression forecasting theory, minimum night flow (MNF) method, bursts and background estimates (BABE) and fixed and variable area discharges (FAVAD) concepts. The methodology allows assessment of the reduction of water supply and the pressure reduction rate in the critical point by two pressure control techniques. Moreover, the differences of two pressure management systems are comprehensively analyzed, and the benefits yielded by the flow-modulated pressure control are greater than the other.

Based on the extended period simulation of EPANET software, a calculation method on leakage modeling is proposed. The aim of the paper is to present the variation pattern of water consumption, water loss and the benefits yielded by pressure management during 24 hours on the basis of the relationships between leakage, consumption and pressure. If it is assumed that the inlet pressure of DMA is reduced from 39 m to 31 m through PRV, the results show that the average daily water consumption and water loss are respectively reduced 10.83% and 20.52%, and the average pressure of the critical point is reduced 21.13%. Therefore, the quantity of daily water loss and consumption saved by pressure management are great, which will produce the great economic benefits annually.

The external water of drainage systems will cause a lot trouble to the operation of sewer pipe systems and waste water treatment plants. It can reduce the efficiency of sewerage treatment and increase the investment of pump stations and the cost of operations. The external water mainly includes underground water infiltration and rainwater inflow. Based on the theoretical analysis and experimental verification, this article put forward a new methodology of calculating the external water quantity according to the different conductivity of sewage and external water. The flow in sewer pipes was precisely calculated according to the relationship among the water levels of manholes, pipe diameters and pipe materials. The article proposed an evaluation technology of sewer pipe operation by analyzing the relationship of sea tide levels, underground water levels and infiltrations. In this paper, the sub-catchment zoning, monitoring equipment arrangement, and data acquisition technology were offered. Also, the tide influence on drainage systems of coastal cities was studied quantitatively based on the analysis of sewage collection ratio, external water amount and pump station operation results. The study results showed that this method is suitable for external water diagnosis and the evaluation of sewer drainage systems.

In traditional fluid control equipment, valves have wide applications in many aspects, including the long-distance pipeline, urban underground pipeline and chemical pipeline. However, internal leaks through valves are a common phenomenon in engineering and lead to medium leaking, medium pollution, and the failure of emergency shutdown and other problems which seriously threaten the safety of pipelines. On-line detection of internal leaks through valves not only effectively prevents accidents, but also decreases the cost of disassembling the valve and pneumatic testing blindly for conventional measurement methods. In this paper, several common failures of valves in gas pipelines - to causing internal leaks through valves, including wear, damage of seal, and their combinations - are simulated and acoustic emission (AE) data are collected during the experiments. Then, acoustic emission signals are analyzed in frequency domain and time domain, and are decomposed into a series of frequency bands based on a wavelet packet. Lastly, a method which combines the feature of wavelet packet-energy entropy with a support vector machine (SVM) is put forward to identify the leak failure modes. The results show that this method can be effectively applied to the on-line detection of internal leaks through valves in gas pipeline.

Pipeline leaks can be caused by third-party intervention, ground movement or corrosion, but also by improper operating procedures and material failure. To make sure a leak detection system works optimally, the correct system has to be selected. Care should be taken during this selection. Specified accuracy and sensitivity figures are often based on a theoretical approach, whereby items as data refresh rates and transient pipeline conditions are easily overlooked. Several methods can be provided for leak detection and location. The selection of appropriate methodology depends upon instrument availability, field devices, communication infrastructure, transported fluids and gases, and performance criteria. This paper starts with "why install a mass balance leak detection system" and "how to choose the system instruments that suit the application, even need the most accurate solution for long distance pipelines with intermediate pumps, extreme elevations and slack line flow conditions. The focus is made on the Instruments Factor. What is important for the instruments working with this system? Mass Balance Leak Detection System does not depend on special instrumentation and field devices, but the overall system performance improves if integrated with ultra-fast scanning sensors and dedicated Leak Remote Units with sufficient processing power. Less known is that modern leak detection systems can provide relevant pipeline information (such as temperature, pressure and flow profiles along the pipeline) which can improve pipeline operation drastically. Finally, the quicker and more reliably a leak can be detected, the quicker it can be repaired and monetary losses can be minimized. Typical leak detection specifications, such as sensitivity and accuracy, are also taken into consideration. Are these specifications relevant to real life situations or do they only refer to fully stationary pipeline conditions that are only encountered in theory? In practice, pipelines always exhibit transients. In addition, the accuracy of the installed instrumentation, data refresh rates, time allowed to detect a leak, position and number of field instrumentation and many other factors influence the performance of a leak detection system. SMB - Statistical Mass Balance; Instrument Factors; "Technische Regel für Fernleitungen" -TRFL (in German rules)

The ultimate goal of pipeline leak detection is to locate the leak source in a timely manner and accurately. A method called "multi-level leak source localization", which is a combination of regional localization, and precise localization was presented to overcome the difficulty of selecting the appropriate wavelet packet decomposition (WPD) components to get the precise localization result. Firstly, the area of the leak source was determined through the signal amplitude attenuation characteristics. Then, the localization results were obtained by the cross-correlation analysis of every WPD component. Finally, the accurate leak source location was obtained through the average of the localization results in the area. Through the related experiments of pipeline leakage detection by acoustic emission (AE) under different environmental conditions (pipeline exposed to the air and buried pipeline), the study confirmed that the presented method can accurately and effectively locate the pipeline leak source (location error was less than 2.43%).

A natural gas pipeline in the Yangtze River Tunnel was constructed via shield method. When the shield machine entered the reception shaft, groundwater inflow and sand inflow occurred in the tunnel 10.2 m away from the inner wall of the reception shaft and led to segment displacement and ground collapse. Drilling was adopted to probe the shield segment displacement and the drill hole deflection was controlled by means of vertical shaft calibration of drill rigs using a perpendicular line, which strictly controlled the accuracy of the probe to determine the displacement of tunnel segments. Segment damage and disturbance were effectively prevented by drilling speed control and blank bit replacement. This detection method, with reasonable technology, meets the exploration accuracy and attains reliable exploration data so that it can provide a reference for similar engineering problems.

Pressure drop is the main characteristic of hydraulic transport in pipelines. How to predict the hydraulic gradient of slurry transport through pipeline is vital in industry. The Wasp method is introduced in the present study for resistance calculation of slurry flowing through 150-mm diameter horizontal pipe. Slurry resistance of two sizes (0.123 mm and 0.372 mm) of sand particle were calculated and compared with the experiment results at different velocities (from 2 to 9 m/s) and overall concentration ranging from 10% to 45% by volume. The results show that the ratio of suspended sediment and bed load are decided by velocity and concentration as well as particle size. It is observed that the resistance of the two-phase carrier fluid (composed of the suspended sediment and water) is the main component of the total resistance and has a major impact on the prediction effect of the Wasp model. The computational model and results discussed in this work would be useful for the applications of slurry pipelines.

Bifurcated pipe is the typical water-diverting structure of a pumped storage power station, the water flow of which is bidirectional and complicated. In order to verify the rationalization of the shape design, water flow under different operation conditions of the bifurcated pipe of a pumped storage power station is studied by using a 3D k - ε turbulent model to simulate head loss, velocity distribution and flow pattern. The result of simulation shows that water head loss on single tube operation is larger than that on double tube operation both in generating and in pumping. Water flow is relatively evenly distributed on double tube operation, which is very complicated on single tube operation.

Water hammer is of great damage to long-distance raw water transmission pipelines. Once a pipe burst accident occurs, the entire city's water supply will be affected. We take a city's drinking water transmission aqueducts as an example, convert the construction drawings and general layout plans with AutoCAD format to DXF format (which can be imported to water supply model systems), extract the physical attributes of the pipes, air valves, control valves, reservoirs and other auxiliary facilities, and establish a computer model of water supply system which contains DN2600, DN2400 and DN2200 pipes with a total length of 71 km, 127 air valves, 73 control valves, and one reservoir. We verify the model by: (1) manually checking the physical properties of the pipe network with inspecting profiles, charts and tables; (2) build the water hammer analysis scenarios through adjusting the control valves on the aqueducts at the outlets; (3) evaluate pipe burst risk by scenario analysis; and (4) set a surge tank at the point of maximum vapor volume to prevent water hammer. The results show that the air valves cannot prevent water hammer as the water hammer protective equipment does and, therefore, evaluating the water hammer risk for the long distance water conveyance system is necessary.

City water logging causes great loss to properties and lives of people. This paper focused on the storm water system in one area of Shenzhen, China. With the CAD drawings from water resources survey results, we converted AutoCAD format drawings to DXF format data (which can be imported to the computer model system), extracted the physical properties of the pipes and ancillary facilities through programming, and established a computer model of the storm water system. We verified the models by manually checking the physical attributes of the pipe network with field observation and inspecting the profiles, charts and tables. According to the storm intensity formula of Shenzhen, we designed nine scenarios to evaluate the storm water system. Their return periods were 0.5a, 1a, 2a, 3a, 5a, 10a, 20a, 50a and 100a, with the rainfall duration from 0 - 200 min. Based on the analysis of these simulation results, the regions where water logging and conduit plugging happened were located. Further, the bottleneck problems of the network were also found. The results show that a computer model is practicable for evaluating the storm water systems.

A cutoff wall is an effective hydraulic structure to protect oil-gas pipeline laying along the slope. It has a great impact on the safety and stability of oil-gas pipeline when it has been destroyed by rainfall erosion. With a certain pipeline as its engineering background, this study took the structural styles and rainfall-caused damage characteristics of cutoff walls along the pipeline into account. A numerical model of cutoff wass was constructed based on: (1) the regularity of regional rainfall and soil-erosion specialties of the slope; and (2) consideration of the interaction among the cutoff wall, pipe and soil, and material damage effects of the cutoff wall. Simulating deformations and interactional effect rules of wall-pipe-soil system under different rainfall conditions, the stress and deformation and damage regularity of cutoff wall were comparatively analyzed. Studies have shown that: (1) cutoff walls present characteristics of tensile failure under rainfall erosion effect; and (2) Increased with the elevated intensity of rainfall, load was increasing and the damage degree and damage range of cutoff wall were expanding.

In the process of long-distance water transmission, as the emergence of water hammer, pipe explosion phenomena have occurred. The surge tank is a stabilizer, working in course of the hydraulic transients, supplying or discharging water to prevent the harm of water hammer in the pipeline. Due to the method of characteristics, a dynamic water hammer model is established. The effect of the surge tank to diminish water hammer is verified with the help of the calculation program, "Compiled". After these works, the location of the surge tank is changed to verify how the pressure of valve at the end (which generates water hammer) is changing accordingly. In addition, three different types of surge tanks (the cyhlinder surge tank, the throttled surge tank, and the dual-chamber surge tank) were installed in the model to analyze their performance as well as their effects of mitigating water hammer. Such work - that tests and verifies the dynamic characteristics of the surge tank by taking advantage of the method of characteristics - is very meaningful for the study of surge tanks. The aim of this paper is to provide an effective reference for surge tanks and water hammer protection researches in the future.

The pressure/flow control system is one of the most important systems in the compressor station of a gas pipeline because it plays the role of safely and smoothly supplying gas for the role for whole compressor station. The control valve is the key equipment in a pressure/flow control system. Proper control valve sizing and selection is essential to operating at a cost-effective and highly efficient level. This paper introducesan overview of theCentral Asia-China gas pipeline project. Secondly, it gives the technical requirements and detailed design principles according to international standards. Finally, it introduces control valve sizing calculation methods and results.

In the Loess Plateau region, floods and geological disasters are of common occurrence. Oil and gas pipeline engineering is vulnerable to floods, landslides and collapse in the gully area, thus seriously affecting the safe operation of pipelines. Gully head erosion protection is the key point of the gully governance. Appropriate protective measures can be taken according to the characteristics of loess in different regions - as well as the topography and soil conditions - to effectively prevent slope runoff discharges, gully head forwarding caused by erosion, gully incision, and gully bank expansion so as to ensure the pipeline safety and improve the ecological environment.

Oil and gas pipelines crossing water areas under the impact of water flow were faced with the risks of floating, deformation, and fracture. Study on safety characteristics of pipelines under the impact loading was significant. Load characteristics were analyzed under the impact of the water flow. The finite element model was established and pipeline stress and strain characteristics were analyzed by the element model. Influences on the stress and strain of pipelines were studied under the action of different flow velocities. The strength criterion was constructed and the safety of pipelines under the impact of water flow was evaluated. The work of this paper provides a reference for the design of engineering optimization.

The energy consumption of the crude oil gathering and transportation system is a considerable proportion in the production cost of oilfield enterprises. Based on the analysis of the production and operation situation of the crude oil gathering and transportation system in a certain oilfield: (1) the main problems of the completed gathering system under the current production and operation situation can be found; (2) the main factors that affect the energy consumption of the gathering and transportation system can be analyzed; and (3) according to these factors and specific situation of the oilfield, the main measures which will be taken to save energy and reduce consumption of the gathering system in oilfield can be put forward.

Long-distance natural gas transmission pipelines are designed to cross large-scale mountain areas with the start of the West-East Gas Pipeline Project in China. A great portion of the pipelines are now threatened by severe landslide hazards. The pipelines could fail, resulting in a great loss because of the landslide failure deformation. Therefore, the spatial arrangement plan of an underground pipeline crossing landslide areas is one of the key problems. This paper presents a new mechanical model of pipeline and landslide under trapezoidal landslide force to conduct the mechanical analysis on deformation of pipeline. A series of shear force, bending moment and defection of pipeline under landslide with different crossing angles can be deduced according to the simplified model presented. Based on a case study of a typical landslide with pipeline underground crossing, the geological mechanical model of landslide and pipeline system can be established. The mechanical characteristics of a pipeline can be conducted under the driving force of a landslide by utilizing mechanics theory so as to determine the position of maximum stress point along the pipeline. Consequently, the optimal crossing depth and orientation of a pipeline can be obtained. The result shows that the proper setting of crossing angle and buried depth can effectively improve the safety of pipelines. Corresponding control strategy suggestions for similar pipeline projects are proposed, as well.

Injecting cable into coiled tubing (CT) is an important guarantee of the oilfield smart job to supply electrical power and signals down-hole to collect and manipulate the real time data. Pumping fluid to inject cable into a reel of CT is a new method for the installation. It is more economic and more adaptable in oil field operation when compared with other conventional ways, especially in operations on an offshore platform. During pump-in, cable was floated under the drag force on its surfaces in the turbulent fluid. Here is how to realize the injection in the initial segment is crucial to the whole installation process. After a brief introduction of the pumping method and device for the installation, the main work was focused on the initial injecting process. This paper modeled the initial injecting segment in the horizontal status, simulated the pumping process by the finite element software and then derived the data from the post processing software to analyze the process. It also carefully analyzed the effect of the different flow velocities in the annulus and the total force on cable. After the numerical study, the related parameters and functions for the injecting operation like pumping rate, working pressure and the total force on the cable were obtained. The theoretical analysis and analog results verified the feasibility of the pumping method for the cable-in-CT system.

This research focuses on the effects of the adjacent surcharge loads on pipelines buried nearby. A calculation model is established based on the theory of Winkler elastic foundation short beam, taking into account the impact of soil deformation which is leaded by adjacent surcharge loads. The Boussinesq basic formulas and the finite difference method are also applied in this model. Consequently, analyses are performed for pipelines varying the load location, geologic condition, pipeline depth, diameter and stiffness through an example. After increasing to a certain value, the pipeline diameter and the coefficients of foundation bed would have little impact on the pipeline maximum displacement. However, the buried pipeline deforms significantly as the burial depth soars. As expected, the maximum displacement of pipeline decreases while the pipe stiffness increases and the location of adjacent surcharge loads pose large effect on buried pipelines.

This paper used the numerical method to analyze the present conditions of the pipelines. Considered here are pipelines of three different diameters and materials to study the pipeline behavior when the nearby tunnel was excavated. During the analysis, five key factors were discussed, respectively: (1) when the tunnel was excavated, including the horizontal distance and the vertical distance between the pipeline and the tunnel; (2) the cross angle; (3) the tunnel excavating procedure; (4) the underground water table; and (5) then found the influence law of the pipelines when the tunnel was constructed. Numerical simulation results showed that these factors above had different levels of effect on the present condition of the pipelines. The horizontal distance and vertical distance between the pipeline and the tunnel are the most influential factors. We must avoid the subway and pipeline parallel during the construction because the pipeline's displacement will be very large and the impact on the underground water table cannot be neglected. Ten meters horizontal distance and 10 meters vertical distance near the concrete pipeline should not be allowed during the construction; that would result in grave consequences to the pipelines.

Glass fiber-reinforced plastic mortar pipe linear deformation caused by temperature changes leads to leakage in the pipes and manhole connection. To solve the problem, blankets are used to cover and lower temperature deformation of light on glass fiber-reinforced plastic mortar pipe. On the base, use the AJ302 basis of concrete pouring agents to guarantee that the manhole in the base is leak-proof. At the spout, use resin wrapping process technologies. Engineering practice has proved that the method is simple, practical, reliable in quality and achieved good economic, social and environmental benefits.

Most shallow-buried multi-pipes of urban roads are flexible, but have some common quality faults. For example, the pipe's spacing is difficult to ensure, and the backfill material between the pipes is difficult to tamp. This paper introduces the construction technology to solve these problems by installing a locating-frame to ensure the distances and using a wave-style rammer to ensure compaction degree between pipes. This technology has the advantages of simple construction, low cost, and prominent social benefit, which have a certain reference value in the construction of shallow-buried multi-pipes of small diameter.

In order to effectively detect small-caliber HDPE silicon core pipelines laid by horizontal directional drilling (HDD) technique, a self-recording instrument, 26 mm in diameter and 190 mm in length, was invented by using triaxial accelerometer and triaxial magnetometer to measure the component strength of the gravity field and geomagnetic field at different points in the pipeline. Then, the attitude parameters (such as pitch angles and magnetic azimuth) of the instrument were calculated to reconstruct the pipeline's spatial curve by using a 3D shape reconstruction algorithm. To decrease measuring errors of pitch angles and magnetic azimuth, numerical correction methods for orthogonality and coaxiality of sensor's axes were analyzed. This paper presents experimental results where the new measuring instrument was used on the worksite, thereby verifying the validity and convenience of its detection method.

The small leakage in the natural gas pipeline in China increased rapidly in recent years. Its overall amount has exceeded 40,000 km and the nation-wide gas pipeline network has taken shape. Therefore, pipeline safety management has gained more and more attention. The signals of sound, pressure drop and vibration - which are produced by small leakages in buried pipeline - are always too weak to be captured by SCADA. But, if the small leakage lasts for a certain amount of time, it can cause very severe damage. Therefore, this paper researched the diffusion rule of buried pipeline small leakage based on the theory of single-phase seepage and high-speed, non-Darcy seepage. It established a mathematical model of seepage using FVM to solve control equations and was finally verified by experiment. By comparing the results of experiment and numerical computation, we built an empirical formula to determine the non-Darcy coefficient and a pressure correction equation suited to high-permeability soil and soil deformation. This model can be used to estimate mass flow of buried pipeline and seepage time to the ground and to provide reference to establish management regulation such as natural gas long-distance pipeline's patrol cycle.

Rock mass stability needs to be analyzed when a pipeline passes through the tunnel engineering and underground cavern project storing oil and gas. The selection of rock mechanics parameters is the most critical point. The rock mechanics parameters are influenced by the mechanical properties of rock, the structure surface distribution, the structure surface nature, and the action of underground water. In this paper, based on the surrounding rock classification system, the relationship between Q surrounding rock classification and GSI surrounding rock classification was researched. Moreover, the Q value was introduced into the Hoek-Brown criterion, and various parameters in this criterion were also determined. Furthermore, the calculation formula of rock mechanics parameters was obtained on the basis of the combination of Hoek-Brown criterion and Mohr-Coulomb criterion used in engineering stability analysis software. In addition, this formula was reasonably verified reasonably by engineering examples. This research could provide guidance for practical tunnel engineering and underground cavern engineering.

Oil and gas transported by station pipeline are flammable and explosive. When a leak occurs, it can easily result in casualties, environmental pollution, and loss of property. Risk assessment methods for a station pipeline are less current. The traditional way to manage a station pipeline in the past 40 years in China, heeds only some of the relevant laws or regulations about station pipeline. The inspection cycle time of station pipeline is fixed. Some station pipeline may not need to be inspected in the fixed cycle time. For a more rational use of inspection funds, developing a method for determining inspection cycle time is important. This approach provides risk assessment for station pipeline. The article introduces the risk calculation model for station pipeline, including the determination of the scenario and the likelihood of failure (LOF) of station pipeline. The risk assessment method is improved when combined with the domestic situation, and has applied by the PetroChina Pipeline Company. Practice shows that the evaluation result gives the risk ranking of station pipeline in the company. Then, the station pipeline inspection cycle time is determined in accordance with the level of risk. The risk assessment method provides a scientific basis for formulating the station pipeline inspection plan.

The leakage rate is the essential parameter of risk assessment and failure consequence analysis for the natural gas pipeline. The size of the parameter values represents the severity of the risk to some extent. The determination of the gas leakage rate is closely related to pipeline characteristics, medium flow state, as well as the leakage holes geometry. It is a complex fluid dynamics problem. Based on the gas diffusion theory, fluid mechanics theory and numerical methods, it is comprehensive in considering the steady state when the natural gas continued to leak, leak moment and non-steady flow after the pipeline upstream valve is closed. The paper establishes the hole-tube integrated model of media leakage rate calculation for long-distance natural gas pipeline. Through the computer simulation, the model calculation results of hole leakage (without consideration of tube gas expansion, and when friction loss is small), big hole leakage, or fracture are very close to the actual. It not only solves the lack of calculation model of the condition between holes and fracture leaks in a traditional leak rate model, but also solves computational problems of leakage rate for a variety of gas pipeline leak modes through an integrated model. It has practical value for the quantitative risk assessment and integrity management of onshore natural gas pipeline.

The leakage of a high-pressure natural gas pipeline can lead to serious accidents and poses a significant threat to people and buildings in the vicinity of the failure location. This paper examines the harm effect distances of different consequences based on harmful criteria. Possible consequences caused by pipeline leakage are assumed and their subsequent harm effect distances are computed using the software EFFECTS. Harm effect distances evaluation was performed considering jet fire and vapor cloud explosion (VCE) as the worst-case scenarios. Results show that, for pipeline leakage, the jet fire produces longer harm effect distances; so, the jet fire scenario should be considered as the limiter for harm effect distances evaluation. Based on the analysis of this paper, harm effect distances caused by the leakage of a high-pressure natural gas pipeline can be evaluated. This will not only be useful to prevent and control natural gas pipeline leakage accidents, but will also provide a good reference for the design of new constructed pipelines.

Safety analysis achieves job risk control and safeguards safety production. This research presents a job risk analysis based on job factors and the job process. Based on historical data and current conditions of potential hazards and accidents, we analyze risk of job factors. Through the division of job steps, we identify the hazard points and analyze the risk within the job process using LEC technique (namely, theGraham method which, though the likelihood of the accident, the exposure frequency of the human body in the hazardous environment, loss and consequence of the accident to determine the job risk), thus providing a control rule for job safety management and to realize safety production.

Transporting natural gas via pipeline is the safest and most economical method. However, with the development of society, there are more construction sites requiring blasting. If engineered blasting happens near a natural gas pipeline, seismic waves from the blast can adversely affect the safety of natural gas pipelines. Using the Shaanxi-Beijing Natural Gas Pipeline as an example, this paper analyses the transfer characteristics of blasting seismic waves based on quantities of explosives, distances between pipeline and construction location, and the different types of pipeline and blasting methods. Furthermore, it studies the influences of blasting seismic waves towards buried natural gas pipeline and proposes safety precautions for natural gas buried pipeline in different situations.

Displacement monitoring (including convergence displacement measurement) is the most meaningful and common monitoring item. However, it is occasionally affected by some factors such as field engineering during daily monitoring results. Unlike the ordinary Grey System and other forecasting methods which cannot deal with such a problem, the Unequal Time Interval Grey Prediction Method is able to deal with unequal interval monitoring data and can predict the stability of surrounding rocks in a timely manner. This model has been successfully applied in the displacement monitoring of the Sanshilipu Highway Tunnel project in Ningxia Province.

Horizontal Directional Drilling (HDD) is highly sensitive to geological conditions, particularly in gravelly or stony grounds with low cohesion. Problems often occur when relatively large diameter boreholes have to be drilled. This is mainly due to the fact that the borehole is only supported by drilling mud. Therefore, in unstable soil conditions, the borehole might collapse after a certain period of time and might lead to a stuck pipe during pre-reaming or pull-back operation. This paper proposes a way for HDD to solve borehole stability problems in sandy gravel soil conditions. It combines the advantages of the pipe-jacking method to avoid the HDD disadvantages. The borehole is supported by intermediate pipes during the pre-reaming and pull-back stage. This method can lower the jrisk during installation and extend the range of HDD applications.

A deep-level electric power tunnel installation located in Shenyang City, Liaoning Province in China and employing a trenchless technology method is described as a study case. In addition to its technical merits, the method provided advantages in terms of social and environmental issues, especially in urban areas. This paper presents a stability demonstration of a pentagonal pipe-jacking shaft using the numerical simulation method with a full, three-dimensional, finite element analysis based on this engineering example. The effect of relay wells on total jacking force is also studied in this paper according to the field measure values. The results show that the deformation and stress analysis of shaft structures are content with the code requirement under the condition of max jacking force. According to the field-measured values of the jacking force drawn with respect to the jacking length diagram, evidence of the reduction in jacking force can be found after installing relay wells.

Horizontal directional drilling is one of the most important processes in trenchless technology. Drill pipes are the most important tools for horizontal directional drilling, but can fail easily. Galling of rotary-shouldered thread connections is the usual failure style of drill pipe, which seriously threatens drilling process safety and leads to great economic losses. In the past several years, a lot of galling failure cases of drill pipes' rotary shouldered thread connections for horizontal directional drilling happened, which caused great economic losses and bad society influence. However, research on reasons for galling failure is rare at present, leading to a lack of prevention concepts for this failure style. In order to control the quantity of galling failure cases, we analyzed various factors affecting the galling failure process of rotary-shouldered thread connections based on typical failure cases, including: material chemical composition, mechanical properties, thread parameter size, thread compound, well trajectory, and field operation. Through the analysis, it was found that thread parameters, compound performance, drill string helical bucking and make-up torque have great effect on galling failure process of rotary shouldered thread connections. In order to control galling failure accidents, it is necessary to control compound quality and standard field operation.

With the development of urban infrastructure, the trenchless technology has been widely applied in many applications, especially in the field of pipeline or subway construction. In these applications, the attitude and position information of the bit is indispensable in the process of drilling. Currently, measurement-while-drilling (MWD) systems are generally based on radiolocation or single accelerometer measurement. In that case, the precision of these MWD systems is limited due to the presence of disturbances. Aiming at this defect, a new MWD system - with multiple sensors and based on inertial technology - is developed in this paper. Note that the measuring range of angle of traditional method is limited. We propose a new while-drilling unit which contains two 3-axis accelerometers fixed on two different planes with a certain angle as redundancy. With the help of the temperature sensor and geomagnetic sensor in the while-drilling unit, temperature compensation and credibility estimation are available. The attitude and position information of the bit, as well as the credibility, is calculated by ARM microprocessor. The method of data calculation is also described in detail. Compared with traditional the MWD system, this new MWD system obtains a better anti-disturbance property and can produce more reliable measurements.

Trenchless technology has been widely applied to renovating and repairing underground pipeline systems which cross the river, road or bustling street; but, the pipelines crossing an embankment are still rarely seen. In order to strengthen the research in this field, this paper takes a sewage pipeline of 120 meters (DN 1500 × 22 mm) crossing the levee as an example. If analyses of the principle of pipe-jacking technology with slurry balance, calculates the slurry pressure and total jacking force, and studies the technology of pipe-jacking construction. Meanwhile, in allusion to the effect that the trenchless pipe-jacking construction has on the deformation of the dikes seepage, this paper also analyzes the cone probe grouting technology and its process monitoring. Engineering practice has proved that the pipeline project application of pipe-jacking technology with slurry balance - combined with anti-seepage technology of cone probe grouting - can accomplish successful crossing. The application of these two technologies is feasible, and can provide some beneficial references for similar projects that pipelines cross the embankment.

With the rapid development of urbanization in China, the planning of a city conduit net (such as the water conduits, gas conduits and electric wire cable conduits) does not always meet the needs of urbanization. Therefore, the trenchless drilling technology came into being and drew increasing attention. However, normal trenchless drilling works cannot be carried out in the narrow areas where the ground sets cannot be placed. This article presents a new trenchless drilling technology - microhole drilling - which combines the high-pressure jet, downhole motor, horizontal well with extremely short radius, and coiled tubing drilling. It can get better performance in these fields and can be widely used in big cities (metropolises).

When laying pipe in sandy stratum by Horizontal Directional Drilling (HDD), the instability issue of borehole wall is obvious due to the lower cohesion. In this case, high-performance drilling fluid is so important that it could help clean the borehole and provide protection around the borehole. In this paper, drilling fluid seepage is discussed based on the experiments with different drilling fluid systems in sandy stratum. The purpose is to find the response mechanism of different areas in radial stratum. Scope of instability around the borehole is determined under seepage processing. A mathematical model of fluid-solid coupling is introduced by the author combining finite difference numerical method. In order to establish the stress distribution in radial stratum after seepage, the numerical simulation work is processed under different drilling fluid pressures, diameters (D), and cover depths (C). Results indicate that: (1) Three different areas - including loose, high stress and original state - are put forward; (2) In order to reduce drilling fluid seepage and keep borehole stability, water loss of drilling fluid should be less than 10 ml/30 min, viscosity is from 30's to 35's, and the thickness of the mud cake should be less than 1 mm; and (3) radial seepage and overflow of drilling fluid are obviously associated with higher pressure and D/C value.

Horizontal directional drilling (HDD) is being widely used as a technique to install large-diameter pipelines. Using this method, there exists annular space after the pipeline is installed in the borehole. The annular space is filled with drilling mud, whose cross-sectional area can reach up to approximately one square meter. When pipeline installations by HDD involve a watercourse area, annular mud may result in several post-construction issues such as: settlement or even collapse of the surface above the HDD bore path; penetration destroy in gravelly sand; or soil deformation of the nearby embankment. Based on the similarity principle, a series of experiments was carried out to reveal the consolidation and deformation law of annular mud. First, an iron experiment box located in the laboratory was filled with sand containing clay; this was designed to simulate the formation. Secondly, a horizontal borehole with annular mud was drilled by a HDD rig and sensors were placed in it to record the stress-strain variation of annular mud during the consolidation process. Meanwhile, samples of annular mud were taken from the box periodically, and drilling fluid tests, soil strength tests and SEM image analyses were performed to obtain the property parameters of the samples. Subsequently, the annular mud was excavated for visual observation and strength measurement after seven months. The laws of seepage and consolidation of annular mud in sand obtaining clay can be obtained through this study and it can supply experimental proof for evaluating the influence on crossing area caused by annular mud using HDD.

The paper presents a monitoring program of an experiment study in horizontal directional drilling aimed at measuring stress and displacement which develop inside the soil of a borehole wall. The study has been based on measurements in fine compacted clayey sand backfilled in a large box. The basic parameters of the clayey sand have been acquired by geotechnical experiment such that it could be applied to numerical simulation analysis. The roof of the box was instrumented with four vibrating wire displacement transducers in different depths along the vertical direction and in the same distance along the horizontal axis. The soil around the borehole was instrumented with newly designed and constructed soil displacement cells based on the stress-strain concept. The device was covered with a layer of silicon sealant to achieve waterproof application. The output of the strain gage bridge bonded to the PMMA element was received by a multichannel receiver and then calculated by computer with the equation developed by formula of materials mechanics. The calibration of the designed device twice revealed that its response is reliable. There are three groups of soil pressure sensors installed into the clayey sand, and each group of them was embedded in ring shape around the borehole with different distances to the center of the borehole. The development of pressure and displacement in the soil was measured during the entire stage of horizontal directional drilling and after drilling.

Horizontal directional drilling (HDD) has long been used for water/sewer line installations on projects where crossing of a river or highway was required and there existed few alternative options for construction of these lines. These installations are typically performed by specialized HDD subcontractors utilizing maxi HDD rigs. In recent years, there has been a growing popularity with the use of HDD in municipal sewer/water installations for distribution lines. These installations are often accomplished with smaller mini- and midi-sized HDD rigs and have traditionally been performed by both HDD subcontractors, as well as traditional open cut contractors who expand their capabilities by investing in their own HDD equipment. Sewer/water lines are typically sized in the range of 8" to 12" diameter (or larger), and many of these size installations fall into the realm of midi-sized HDD rigs on the small size lines (typically 8-10") and smaller maxi-sized HDD rigs for some of the mid-sized to larger installations (typically 12" and larger). As the demand for HDD within the sewer/water market sector continues to grow, there will be an increase in the need to utilize maxi-sized HDD rigs to perform this work. As many HDD contractors already understand, there is a large operational difference between midi-sized and maxi-sized drill rigs. Add to this that more traditional open-cut contractors are investing in their own HDD equipment, and also considering the differences in procurement methods on municipal projects, it is clear that contractors and engineers will face unique challenges in successfully utilizing maxi HDD rigs on sewer/water projects. This paper will look at the trends in the industry with regard to the growing utilization of maxi HDD rigs for sewer/water projects and attempt to identify the variables that drive or preclude the use of these maxi-sized rigs for this particular market sector.

Due to the complex working environment and relatively backward manufacturing technology, an important industrial tool - the air winch - faces a lot of problems, such as wire rope breaking and brake instability. This paper presents a new, mechanical loading, tower-type air winch performance test platform designed to testanair winch after it is manufactured. In order to ensure security during the test, this paper proceeded with numerical analysis for the bracket. Results of the analysis showed that the maximum stress of the bracket when loaded was 10 t at 156 MPa (which was far below its yield stress), and its maximum displacement was 0.527 mm (which would not produce large deformation). The natural frequencies of the bracket's free mode are smooth sequential (which do not exist in local breakpoint), and the interval of each frequency is large; thus, it can avoid the close mode. The first mode frequency is 37.255 Hz, so the bracket can avoid resonance caused by the vibration of the system due to the instability of the gas source during the test. This paper also analyzed the stress of the bracket during the test to help the operator predict the danger point and prevent the occurrence of overload. In addition to introducing a new mechanical loading tower type air winch performance test platform, the authors also present a detailed analysis of the bracket. The new test platform can effectively compensate for the lack of air winch performance testing in domestic manufacturing.

MWD technology in a coal mine is superior in its high drilling efficiency and precise control of drilling trajectory. This applies generally to gas extraction and structure exploration in coal mines and will also be used gradually in water prevention and control. Presently, drilling construction for water prevention and control in coal mines is mainly by rotary drilling, which has low efficiency construction, small range of grouting reinforcement, and general reinforcement effect. Through the application of grouting reinforcement in the ZhaoGuYiKuang coal seam floor, MWD technology has high efficiency construction, wide grouting reinforcement, and good reinforcement effect in the coal seam floor. Based on the superiority of MWD technology and the tendency for serious water disaster in coal mines, the technology will have a promising prospect in the application of water prevention and control in coal mines.

In a large-diameter pipeline laying project of horizontal directional drilling, residual buoyancy often causes the pipeline contact with the borehole wall of the hole, which often leads to an increase in pipeline laying resistance and affects the success of a project. On the basis of summarizing the predecessors' achievement in this paper, and aiming at this phenomenon, the research of designing the track-laying pipes was done under stress conditions. The paper establishes the mechanical model of the bending section and the straight section of the embedded side and the pull-out side in the ideal curve. The function relation is proposed between the fluid volume and the time delay when the pipe is dragged back, and intelligent control in the amount of fluid is realized in the process of large-diameter pipeline laying. In the analysis of the engineering case, the relation provides theory and the suggestion for the pipe-laying construction in the balance of the pipe buoyancy and the reduction of the pulling pipeline resistance.

More and more people are moving to the world's urban centers. Big cities are turning into megacities with more than 5 million inhabitants. Most of these megacities grow up in coastal areas. More than 40 percent of the world's population already live within 100 kilometers of the sea. Another 40 percent live in cities along the rivers. Thus, the majority of the world population lives close to water. The challenge to match in these places is to provide people with sufficient potable water and to handle sewage disposal to assure health and quality of life. In the construction of utility infrastructures in coastal areas or in river regions, tunneled outfalls, intakes and landfalls are an effective and sustainable method. With the help of sea outfalls (including river outfalls in the following), wastewater can be transported away from the coastline or river bank and discharged at locations where diffusion, dispersion and decomposition are enhanced. The municipal wastewater may be fully treated, pre-treated or untreated. Water intakes can be constructed, for example, to supply water for desalination or for power plants. If no beach or sandy floor exists near the plant location, or if the site conditions are inadequate for infiltration, a tunnelled offshore intake system is the ideal choice. The growing worldwide demand for oil and gas makes the construction of pipelines (on- and offshore) necessary. In the paper, advantages of trenchless installation techniques and methods for trenchless installation of offshore lines have been introduced. How to choose the trenchless method due to differing geology has also been illustrated.

Analysis of ground surface settlement has been an important technical problem in urban subway shield construction process; but, it is difficult to forecast and calculate settlement accurately. This paper analyzes the main causes of surface settlement due to shield construction and summarizes the influence of several important parameters to surface settlement. Then, Midas GTS software was used to: simulate the shield construction process and calculate ground surface settlement; to calculate stress, strain and displacement of overlying strata above the shield-driving machine and to, obtain calculated values of surface settlement which compared with field measured values. Practice has proved that this 3D numerical simulation method is in accordance with fact and provides a useful reference for the subway shield construction project.

Nan Tanhai slurry shield tunnel belongs to a key submarine, one in the second pipeline project of Guangdong Provincial Natural Gas Grid. This paper mainly deals with the structural design of its working shafts and the support of its subaqueous section.A diaphragm wall and reinforced concrete lining are elaborately used to compose the support structure of the two working shafts. Meanwhile, six reinforced concrete segments are applied to constitute the fabricated support ring of the submarine section for the tunnel, which is driven by means of slurry shield machine. The installation of gas pipes in the slurry shield tunnel is also illustrated in the paper. The summary on the structural design of the Nan Tanhai slurry shield tunnel for laying liquefied natural gas (LNG) pipes may provide reference for similar projects under analogous conditions in China.

The water-rich, silty, fine sand stratum is characteristic of high sensitivity and poor foundation stability. Shield tunneling in this kind of stratum is prone to a negative impact on the surrounding environment. The block that restricts the technology development of shield tunneling in water-rich, silty, fine sand stratum is summarized. The subsidence control is introduced, including the soil warehouse pressure stabilization, avoiding downtime, keeping reasonable driving speed and strict posture control, and suitable synchronous grouting type. The series of measures has important significance on reducing the surrounding environmental impact.

Xi'an Metro is the first urban subway built in loess stratum in China. Loess is the continent unconsolidated sediments formed under the quaternary arid and semi-arid climatic conditions. When dry, the loess stratum has high strength. When mixed with water, its strength decreases dramatically as particle bonds vanish. Its special engineering geological properties have brought about serious technical challenges to shield tunnel construction. Based on the Xi'an metro line 1 project passing under the Ancient City Wall, a three-dimensional, nonlinear, finite element model was established to analyze the impact of shield tunnel construction on the city wall. Priority was given to the effect of shield tunneling in loess stratum on the ground surface's transverse and vertical deformation and the principal stress change. Results show that the maximum surface came after the shield tail passed the city wall. The closer the monitoring section was to the tunnel, the larger the settlement would be. The extent of the city wall's incline was mainly determined by disturbance of the soil and the jacking force. The jacking force was almost proportional to the incline. Also, due to the shield tunneling, stress concentration occured at the foot of the city wall. Some reinforcement measurements should be taken into consideration.

This article intends to analyze and compare the seismic dynamic behavior of one double-track shield railway tunnel and two parallel, single-track shield railway tunnels connected by transverse connected tunnels. The numerical stimulation method is employed under the background of a scheme comparison during the design work of Qiongzhou Strait shield tunnel. The stresses and displacement behavior of tunnels in these two schemes (subjected to different seismic loads) are obtained by the Fast Lagrange Analysis of Continua method during numerical stimulation. Calculation results show that both kinds of structure are subjected to repeating loads. The response properties of the double-track scheme are similar to the normal condition. The maximum stresses appear in the conjugate 45-degree direction of the tunnel's cross-section. In the single-track scheme, an obvious stress concentration appears on the cross-position of the main tunnels. Their transverse connected tunnels and the values of them are bigger than those in the first scheme. Second, the displacement difference of the tunnel's different parts in the first scheme is larger than that in the second scheme. The conclusion will provide a new influencing factor of the comparison between those two schemes and will be an instruction to the seismic design and construction of practical engineering.

Based on the theory of plate strength, a mechanical calculation model was obtained to analyze the reinforcement scope of sandy pebble soil at TBM launching and breaking through area. In the model, the reinforced soil was simplified to a four-sided, simply-supported rectangular plate. Based on the Levy-Type solution for rectangular plates, the largest shearing and tensile stress principle was used to obtain the scope of the reinforced soil. Using MIDAD/GTS software, a three-dimensional numerical model was established to analyze the thickness, displacement and strength of reinforced soil. The result showed that it can meet the safety demands of departure and arrival of TBM when the thickness of reinforced soil is between 1 and 1.5 times the diameter of the tunnel.

The basic research method for this paper is the stratigraphic structure method - carrying out finite element analysis for the stress, strain, and deformation of the subway shield tunnel lining segment, the segment joint and segment lay-up rubber cushion layer, and based on considering the three basic factors of subway shield tunnel buried depth, segment layup rubber material, and ground heap load. The finite element analysis of this paper uses the three-dimensional entity finite element model [Koyama Y., Konishi S., Arai Y. and Okano N. (1997)], which includes lining segment, segment lay-up rubber layer, and the surrounding soil. The research combines with the geological conditions of the Beijing subway and takes into account the tunnel lining design, rubber layer of material anticipates, the tunnel buried depth and many other factors. The results of the study show that the stress, strain and deformation of the whole subway shield tunnel lining segment and rubber layer are relatively homogeneous. The segment joints appear discontinuous. Displacement, which increases along with the tunnel buried depth, increases while the rubber layer elastic model decreases. The segment joints exist in obvious tension stress concentration phenomenon. When the tunnel buried depth exceeds 75 meters, the concentrated tensile stress is beyond the limit of reinforced concrete segments' tensile stress. The study has a certain theoretical and practical value on the subway shield tunnel lining segment design.

Evaluation of the impact of tunneling on the stability and integrity of the existing pile foundations is a key factor affecting the tunnel safety. The Chengdu Metro Line mainly passes through water-rich, sandy, cobble stratum which has characteristics such as loose structure, poor self-standing ability, and no cohesive force. Therefore, there are no precedent projects for reference. Based on the Chengdu Metro Line 1 adjacent to the airport overpass, numerical simulation was carried out to study the excavation-induced pile response. In numerical simulation, a three-dimensional finite element model was established to study the behavior of pile foundation to adjacent tunneling in the lateral direction of pile foundation. The numerical analyses have included the inherent relationship between the internal force of the pile foundation, the frictional force, and the deformation of the pile foundation during shield tunneling. The results show that the impact on the pile foundation lies mainly in the influence of the shield tunneling on the side-friction force and the tip resistance of pile foundation. It can be found that an inherent relationship exists between the internal force, side-friction force and the deformation of pile foundation, which is of great significance for the assessment of the impact of tunneling on the stability and integrity of the adjacent pile.

Metro tunnel construction in karstic usually involves collapse, water outburst, slurry outburst, and over-buoyancy problems. This paper will focus on the risk evaluation and solutions of metro tunnel in typical karstic area for both the construction and service phases. As case study, geo-condition data and some metro tunnel design will be presented in this paper to analyze the potential problems in karstic areas in Wuhan. Finally, treatments are suggested as the solution for metro tunnel projects and will be discussed in detail.

The Gongbei Tunnel of the Hong Kong - Zhuhai - Macau Bridge Zhuhai Link is a world-class project. Its underground excavated section, passing underneath the Gongbei Port, is crossing strata with very complex engineering geologic conditions. It has the soft-soil characteristics of high compressibility, high thixotropic nature, high sensitivity, high water content, high void ratio and low strength, making the stratum deformation control very difficult. In the totally 255-m-long underground excavated section, the plane alignment is composed of easement curve and circle curve. The advance-support pipe-roofing system is formed around the laminated structure by 36 steel pipes with a diameter of 1620 millimeters. Underground excavation is performed after the water seal curtain is formed by the segmented freezing method applied on the soil bodies between the pipe roofing. This project is the largest pipe-roofing group, long-distance, curved pipe jacking project in the world with unprecedented challenges in terms of design and construction due to its high technical content and great difficulty.

In order to explore the influence on ground subsidence induced by shield tunneling in Shenzhen Metro Line 7, this paper focused on the Taoyuan satiation to Shenyun satiation. A 3D numerical simulation on ground movement was constructed with FLAC3D and compared with the empirical formula method to verify the result. It was then concluded that the advanced simulation model was optimized.

The first stage of Wuhan Metro Line 6 was designed to utilize the shield method for tunnel construction, which consists of two sections - one from Sport Center SouthSstation to CheCheng East Road Station, and the other from CheCheng East Road Station to JiangCheng Street Station. Selection of the shield machine involves geological conditions, hydrologic geology, and unfavorable geology of the route on the basis of preliminary investigation. The pumping test also will help shield machine selection for some special geology. With the aim to provide technical support for construction design, this paper is focused on the shield machine selection by analyzing data of geological exploration and comparing different shield methods.

An important challenge in analysis and design of buried pipeline against the earthquake effects is how to model soil-pipeline interaction. In 2009, Abdoun and his colleagues presented results of tests on buried polyethylene pipelines subjected to strike-slip faulting. The results showed that, for a small ratio of H/D, maximum lateral force of pipe has a good agreement with ASCE relationships; but, a large ratio of H/D is 3 times smaller than ASCE specifications. In this study, after verifying numerical results, the effects of soil parameters on the pipe axial and bending strain were investigated by sensitivity analyses. Finally, it is shown that centrifuge test results for large ratio of H/D are not only reliable and ASCE relationships are very over-estimated for this case, but also the pipe wall thickness has a significant contribution to the pipe soil interaction, whereas it is neglected in ASCE relationships.

This paper presents the research on the bending strain capacity of 40" X70 Line pipe. Full-scale testing of pressurized pipe of specific design factors was conducted to demonstrate the compressive strain limit. The numerical analysis - based on laser measurement, reverse engineering and finite element method - was also performed to investigate the pipe buckling behavior. The results of the full-scale testing imply that the finite element method can be used to effectively predict buckling strain of line pipe.

Seismic behavior of the gas pipelines has been considered due to their vital role and also because experiences with recent earthquakes demonstrated a poor seismic performance. This research attempts to improve the seismic performance of gas pipelines subjected to near-fault (NF) earthquakes by utilizing supplemental damping. In this study, the buried gas pipelines of a zone in Tehran were modeled using finite element analysis (FEA). Moreover, nonlinear time-history analysis was performed by seismic scaled records of NF earthquakes. The results determined the critical points of pipelines which failed due to seismic waves. Friction dampers are designed to have moving parts that will slide over each other during a strong earthquake. When the parts slide over each other, they create friction which uses some of the energy from the earthquake that goes into the system. So, as a proper solution, the friction dampers were employed for better seismic performance of the system. The obtained results after damper installation showed that the failure points were retrofitted efficiently.

Trenchless technology for replacing worn-out underground pipes has great advantages in municipal engineering compared with conventional excavation technology. In order to meet the demand of the huge potential market of pipeline rehabilitation, various trenchless methods have been successfully developed. Cured-in-place pipe (CIPP), which uses new composite material, has been recognized as an efficient and convenient trenchless method, having been developed and tried for many years. Potential applications based on such a method (specifically, their use for minor diameter tubes) have been realized. In this paper, a comprehensive review is presented on the research and development related to composites materials for CIPP, including fiber material for reinforcement, method for fabric manufacturing, and thermosetting resin for matrix and impermeable layer. Information on that research and development has been summarized in this paper. Other issues regarding the green composites used in pipeline rehabilitation, research challenges, and future trends are also discussed.

The underground pipeline systems span thousands of kilometers and form a significant part of the infrastructure of China. These pipelines are aging, overused, possibly mismanaged, and neglected. They are usually "out of sight and out of mind". The assessment system of pipe inspection and rehabilitation is aiming to simplify inspection data processing and rehabilitation method selection. This paper's focus is on the software development of this system by discussing the database building and modular design.

Trenchless pipe replacement, which involves pipe bursting, is a construction method used for replacing existing and deteriorated underground pipelines with totally new pipe of equal or greater diameter. It is a sustainable and cost-efficient pipeline replacement method as compared with the conventional open trench activities which can result in noise, traffic disruptions, and environmental impacts. In recent years, the use of trenchless pipe replacement has grown significantly in China. This paper provides discussion on several key technical problems in pipe bursting operations, including ground displacement, soil conditions, scratches on new pipe, and pull force analysis. The results from this work should help pipeline managers and engineers in planning successful pipe bursting and assessing risk. To gain some insight into the pipe bursting, this paper introduces the basic mechanism and installation procedure of this trenchless process.

Non-stop transmission blockage technologies are the preferred approach used to maximize safety while performing piping maintenance. As an important part of non-stop transmission blockage technologies, the structure of blockage plays an important role in the quality of pipe plugging. Furthermore, it is difficult to plug the pipeline successfully all at once. To address this difficulty, the authors are presenting a newly developed pipeline double blockage system in this paper. The double blockages can sweep the residue in the pipeline created by its first blockage to guarantee the plugging ability of the last blockage. By analyzing the double blockages' static analysis, the results show that the newly developed pipeline double blockages can completely meet the requirements of the work environment. The plugging ability of the rubber cup ring was checked with results showing the plugging ability of double blockages could reach 9.186Mpa. This completely meets the 6.4MPa pressure requirement in pipelines even with more than 40% redundancy, and the new blockage structure has the ability to maintain the pressure a long time without leakage. The new Double-Plug is safer and more efficient than traditional ones which is a needed innovation in pipe plugging technologies.

The experimental conditions of cutting single-layer oil pipelines using diamond string bead wire are introduced in this paper. The structure characters of single-layer oil pipelines and the variation of area and notch width of the string bead wire cutting pipes are analyzed. Through the cutting experiments, the feasibility of cutting single-layer oil pipelines with string bead wire is verified, the efficiency of diamond wire saw machine is measured, the working stability of the equipment is tested and the working conditions of the hydraulic systems are observed. Also, the operation specifications are clarified of cutting single-layer oil pipelines using diamond string bead wire. Through the detection and analysis of relating technical parameters, the rational cutting parameters are obtained and the using conditions of the string bead wire are objectively evaluated.

With the frequent occurrence of pipe-failure accidents of urban water mains and the increasing application of trenchless rehabilitation technology in municipal pipeline systems, this paper focuses on a crucial matter of the trenchless rehabilitation of urban water mains: lining design. Rational design of linings plays a significant role in a certain trenchless pipe rehabilitation engineering, which is directly related to the final structural strength of the rehabilitated pipe system, the flowing capacity of the rehabilitated pipe and the final cost of the project. As water mains are pressure pipes and complicated pressure waves may occur in the running period, the lining design of water mains is quite different from the pipes which mainly withstand external pressure. However, the existing lining design theory mainly concerns external pressure, seldom concerning internal pressure. So, this paper tries to establish a set of new lining design methods for the rehabilitation of water mains, concerning external pressure as well as internal pressure waves. Based on the summary of the existing lining design theories, the lining design methods in this paper are established through mechanical analysis of the conditions of pipe loads and the strength of the rehabilitated water mains resisting inner and outer loads. Finally - through a series of mechanical analyses and references of existing lining design theories and related mechanical models, this paper provides a set of relatively effective lining design methods for different trenchless rehabilitation techniques used in water mains. The study in this paper will offer references for the future trenchless rehabilitation of urban water mains.

The optic-fiber transmission system can supply large-capacity and high-reliability channels for SCADA data, voice, security, and office automation of oil (gas) pipelines. The same trench-buried method is widely used in the optic-fiber cable installation of the pipeline project since it has many advantages, such as, reducing the earthwork, saving land, and using the ipeline facility to protect the cable. To direct and regulate the same trench-buried project after a long period of practice in many projects, we formed a set of standard system and basic work. An example is the petroleum industry code: "SY/T 4108 design and construction code of optical fiber cable (high-density polyethene silicore duct) laying in the same trench with oil (gas) pipeline", which was first published in 2005 and updated in 2012. However, the same trench-buried method still has some key problems on engineering and construction aspects, such as: the selection principle of laying method (direct bury or blow in silicon duct) has not established a theory system; pipeline construction makes negative influence on optic-fiber cable installation quality. At first, this paper will be considering comprehensively with the terrain & landform factor, local develop level, crossing frequency and the steps and method of pipeline installation to give out a conclusion about laying method with high utility and systematicness. Furthermore, the paper will illustrate the reason of discontinuous construction of oil (gas) pipeline and the damage which was made during pipeline construction process, and to proposed the guiding principles and optimization suggestions to improve the quality and service life of optic-fiber cable in same-trench buried oil (gas) pipeline project.

Grouting reinforcement with borehole is an important method for water in-rush of the seam floor in an underground coal mine. In order to improve the grouting reinforcement effect with a borehole in the coal floor, the directional drilling technology with MWD is put forward and is used to drill a borehole inthecoal floor. Meanwhile, drilling requirements, process and technical points of the reinforcement directional borehole are studied in this paper. According to the experiment in the Zhaogu coal mine, the advanced management of the seam floor has been realized by the directional hole. The grout amount of a single directional borehole has been increased to double or triple times as compared with a rotary drilling borehole. This offers technical support for prevention and controlling of mine water.

The deformation behavior of the rock and soil is a key problem in the construction of the underground pipe work and will directly influence the time limit and difficulty of a project. Actually, for the underground rock mass, the construction of pipe work is a stress release process which makes the deformation characteristic of the rock mass totally different with other conventional constructions, such as building construction, road and bridge construction. The reason is that the stress paths of the two kinds of engineering are different; one is download stress path and the other is upload stress path. So the mechanical property and deformation characteristic of a kind of soft rock under both download and upload stress paths in the Three Gorges area were studied by using the elastoplastic modeling method. Through the experiments of lamellar marlstone of Badong formation, the manner of the interaction between plastic volume stain and shear strain, the direct effect of the plastic volume stain on shear resistance were investigated, and the conclusion that stress path is exactly the comprehensive performance form of the interaction between plastic volume stain and shear strain which has been proved by the trixal experiments of soft rock. Finally, the deformation behavior of marlstone was used to calculate the settlement in the numerical simulation of the underground pipe work's construction.

In most of the real-world cases, multiple segments are involved in a single project. However, there is no single model developed yet to aid the selection of appropriate method(s) based on the consideration of multiple criteria. In this study, a multi-segment conceptualizes a combination of an individual or a group of mainline, manhole, and lateral. Multi-criteria takes into account the technical viability, direct cost, social cost, and carbon footprint in pipelines. Two different segments analyzed are an 8-inch diameter, 280-foot-long gravity sewer pipe, as well as a 12-inch diameter, 264-foot-long gravity sewer pipe. The results are summarized according to the ascending order of total cost for different method sets. It is found that a selection of an appropriate method set results in significant cost savings for a multi-segment project. Thus this paper represents a model for the multi-segment method(s) selection with the simultaneous consideration of multiple-criteria.

Tension cracking and compression collapse of concrete-weighted coats are carefully included to build up the nonlinear relationship between bending stiffness and curvature of the Cased Insulated Flowline system. Based on the nonlinear bending stiffness trenching and elevating models of this kind of insulation system are built to calculate the additional moments in the field joints and the damage of concrete-weighted coat in those installation statuses, and even the shear forces in CIF pipe coats. Moreover the analytical formulae describing the static response of CIF systems on an elastic foundation are developed by transfer matrix method.

Special conditions in coal mines have led miners to determine that water is the best purging medium in sub-horizontal drilling construction. However, water caused many inconveniences in water-sensitive formations which often appear in gas holes. In response to the identified problem, this paper provides several solutions and illustrates how to execute different methods according to different conditions and cases.

Shield tunneling is one key big-river crossing method for gas pipeline. For the limited tunnel inner space, steel brackets are always used for supporting pipe weight and relative slip friction. This paper determines the most suitable pipe bracket type and uses the software ANSYS to analyze bracket stress conditions. The calculation results show that the steel bracket structures are a safe solution for strengthening underwater pipelines.

The major safety problem of in-service welding of municipal gas pipelines is burn-through and hydrogen induced cracking. In this paper, a numerical model to analyze the thermodynamic characteristics (temperature field and allowable stress) during the welding process at different working conditions is established. This model is then applied to a test case: the leakage section of the Harbin-Yilan long-distance transmission pipelines. In this case, the impact of working parameters during the welding process (pipe-wall casing thickness, welding energy input and velocity of the flow medium) on the temperature field and allowable stress is analyzed. The optimal working parameters to avoid burn-through and hydrogen-induced cracking are also derived. The testing case shows that the model developed in this paper is useful in providing technical support for online welding process and, therefore, can be applied widely in practice.

The heart of the screw drill [also called positive displacement motor (PDM)] is the rotor, which decides the work efficiency and performance of the screw drill. In this study, an experimental analysis was made to explore which factor - in all of the factors - was the main one that caused the failures of the rotors. Also, another attempt was made to analyze the failures of the rotors with a special testing set in real working circumstances. Furthermore, an even deeper analysis was made to get a more accurate and abstract discipline with some related mechanism. In conclusion, the solid particle and the salty additive are the main reasons; corroder wear caused the wear of the chromium layer; and plasma spraying technology performed better than the other way. Finally, some advice was put up on the scale of rotor manufacture and application.

Through the detection of water samples and scale samples, and the analysis of the scaling factors of oil well diving pump and pipelines in Xing ancient buried hill reservoir, the new neutral green scale inhibitor was developed and the mechanism of the scale inhibitor was investigated. At the same time, a way of casing continuous loading was proposed to solve the scaling problems of oil well diving pump and gathering pipeline. The results of laboratory evaluation experiments showed that the new type of scale inhibitor still had a better effect at a high temperature of 160 degrees.

Energy-saving and environmental protection are key factosr in engineering practice. So, the reasonable choice of steam pipe insulation material and an economic insulating layer thickness to reduce the wasting of resources and project cost seems very significant. In this paper, according to the advantages and disadvantages of different kinds of thermal insulation materials, a double-insulation structure with two kinds of materials together is designed, as is the mathematical model through the heat transfer and the calculation of heat loss. With economic costs as the function, and in accordance with the restriction of temperature and heat dissipating capacity, taking the optimization method to program could resolve the economic thickness of the optimal insulation layer, which is better for the selection of steam pipe insulation material and the design of insulation layer thickness.

This paper introduces two advanced technologies: (1) a controlling and monitoring system used in ground measurement and( 2) a quantitative risk evaluation of high sulfur gas development under complicated 3D topographic conditions. Both of these technologies have been successfully used by the China National Petroleum Corporation (CNPC) in pipeline projects located in high sulfur gas fields. Overpressure safety release technology, emergency shutdown (ESD) technology, as well as the formation fluid hydrogen sulfide real-time processing technology were all used to assure a high level of security control. CNPC used real-time monitoring of hydrogen sulfide content and real-time image information to detect and transmit information by wired and wireless means via their monitoring system. A quantitative calculation method was used to determine the concentration and diffusion of hydrogen sulphide based on a 3D terrain model. This diffusion model helped eliminate the probability of a blowout incident and the probability of receptor lethality in the blowout of a sour gas well. It helped determine acceptable levels of individual risks, which were transferred to a determination of risks at a regional level. By introducing these two technologies, this paper provides new means to assure high sulfur gas fields safety.

In a product oil pipeline protected by coating combined with sacrificial anode cathodic protection, it was observed that the CP protective potential fluctuated widely, out of the range of 0.85~1.5V (vs. Cu/CuSO₄). Field survey showed that the pipeline suffered serious dynamic stray current from the direct current system. In this paper, the effect of stray current on buried pipeline was analyzed and criteria reduction methods of DC stray current interference were discussed.

With the high development of oil and gas pipelines, the natural environment, the region, the topography, and the geological conditions where many large-diameter oil and gas pipelines passed by, becomes more and more complex, and the pipeline operation parameter changes are greater than before. Thus, current standards already cannot satisfy the need of pipeline construction in China. According to domestic and international oil and gas pipeline corrosion protection standards, combined with the actual problems in operation management, comprehensive comparison was carried out in criteria for cathodic protection of buried steel pipelines criteria, selection of reinforced thickness coating, criteria for external surface cathodic protection for the bottom of steel storage tank, selection of zinc reference electrode, etc. Finally, some solutions and suggestions are pointed out. It was suggested that the Pipeline Research Institute should carry out research of the criteria for evaluation of the cathodic protection effect of the underground metallic frameworks under different operating temperatures. Thus, to make it clear in different pipeline cathodic protection effectiveness, it should: (1) propose unified criteria for external surface cathodic protection for the bottom of steel storage tank; (2) improve the grade of anti-corrosion coating for buried pipeline in station and valve house requirements; and (3) strengthen the quality control of the anti-corrosion project in long distance oil & gas pipeline.

Pitting corrosion is one of the major forms of damage for Alloy 690, which is one of the usual used materials in SG tubing. It is very important to understand corrosion behavior deeply to ensure structural integrity. In this paper, the electrochemical experiments are used to analyze the corrosion characters of alloy 690. The results show that the corrosion rate is nearly to 0.00948 mm/a at 25° C, 0.01 mol⋅L^-1 NaCl+0 mg⋅L^-1 O₂. The repair of the pitting is easy when the oxygen content is relatively high. Chloride ions in the solution have a certain impact on the repair potential and great influence on the pitting initiation potential. The pitting initiation potentials change from 0.64 V to 0.50 V, then to 0.37 V (referring to SCE) when the content of chloride ions increases from 0 mol/L to 0.001 mol/L to 0.01 mol/L. The competition between repair and breakdown will lead to the result of the peaks current. The repair of oxide film becomes more difficult under high potential. The difference in value between pitting initiation potential and repair potential are -44.1 mV, 0.0 mV, 186.0 mV and 245.2 mV, respectively, when C_Cl- equal to 0 mol⋅L^-1, 0.001 mol⋅L^-1, C_Cl-=0.005 mol⋅L^-1 and C_Cl-=0.05 mol⋅L^-1. The above conclusions are important for recognizing the corrosion mechanism of Alloy 690.

Sulfate-reducing bacteria (SRB) is a main microorganism in aviation kerosene causing pipeline corrosion. The corrosion regular of SRB in aviation kerosene pipeline (X70 steel) is studied by electrochemical impedance spectroscopy (EIS), potentiodynamic scanning polarization, etc. The results show that SRB participates in and accelerates the corrosion of steel pipe. The anodic process of pipeline is blocked and cathodic depolarization is promoted. Corrosion reaction is controlled by the cathodic process. The exits of SRB affect the AC impedance characteristics of the pipeline. At the same temperature, and with the increase of the SRB concentration, the corrosion current density increases, the charge transfer resistance decreases, and the biofilm resistance first increases and then decreases. This means that the pipeline corrosion will be more serious with larger SRB concentration. Under the same concentration and when the temperature is increasing, the corrosion potential is negatively shifted. The higher the temperature will be, the greater the degree of negative shifts, which results in the decrease of pipeline's corrosion resistance.

The stress corrosion behaviors of submerged arc welding X80 pipe, widely used in the West-East Gas Project II, are studied in five typical soil simulation solutions: (1) made from brown desert soil collected from Hami of Xinjiang Province, (2) meadow solonchak collected from Yumen of Gansu Province, (3) cinnamon soil collected from Yichuan of Henan Province, (4) yellow-brown soil collected from Wuhan of Hubei Province, and (5) red oil collected from Zhangshu of Jiangxi Province, respectively). The results showed a certain degree of stress corrosion susceptibility of X80 pipeline steel studied in those soil simulation solutions, but they were not serious. The stress corrosion susceptibility of the X80 pipeline steel gradually decreases from Yumen (meadow solonchak) soil, Yichuan (cinnamon) soil, Wuhan (yellow-brown) soil, Hami (brown desert) soil and Zhangshu (red) soil. Serious pitting occurred on the specimen in red soil simulation solution. The corrosion behavior of X80 pipeline steel in the other four kinds of simulation solutions was governed by general corrosion, although there were a few pitting occurrences on local positions.

The fracturing fluid with solid particles used in the process of high-speed injection into high-pressure pipe manifolds will cause serious erosion damage, which leads to serious material loss and equipment failure. This paper discusses an experimental study on the main factors affecting the erosion rate of alloy steel materials for high-pressure pipe and tee as impact angles and impact velocity by new erosive wear test machine. The erosion rate model was established based on the erosion theory and the results of erosion experiment. Computational fluid dynamics (CFD) analysis has been used to predict erosion behavior in high pressure pipe and tee geometries that are highly susceptible to erosion in the process of fracturing operation. With standard k-ε turbulence, discrete phase and erosion model, the erosion wear rate on the inner wall and velocity characteristic in straight pipe and tee were obtained. The results show that downstream triplet and dorsal competent near branch place are easy to wear. The study is expected to provide reference for high-pressure pipeline defect detecting and optimization design.

With further development of oil and gas resources, corrosion environment of gathering lines became more serious. Designers must consider H₂S cracking and H₂S corrosion, especially in oil and gas fields with H₂S and CO₂ rich gas. In this severe, sour environment, carbon steel with inhibition was not ineffective or infeasible in combating corrosion and cracking. Nickel-based, corrosion-resistant alloy (CRA) could resist corrosion, but its expensive price often makes it difficult to provide the economic justification for its use. Therefore, bimetallic-lined pipe, which has a liner pipe made of CRA and an outer pipe made of low-cost steel, might be an effective solution to the corrosion problem. Application of bimetallic-lined pipe in oil and gas field environments has been a topic of signification interest, involving both performance and economic questions. This paper analyzes four anti-corrosion measures: (1) carbon steel with corrosion allowance, (2) carbon steel with inhibitor, (3) CRA and bimetallic-lined pipe from technical and economic perspectives. The results showed that bimetallic-lined pipe had the greatest advantages in technology and economics. So far, however, bimetallic-lined pipe has not been used as gathering lines for sour service in China. There are still many questions to deal with. The paper describes three primary questions and puts forward some proposed solutions, including: (1) material selection and performance control; (2) manufacturing technique of pipe fitting; and (3) assessment of girth weld procedure. Ultimately, the obtained conclusion is that bimetallic-lined pipe owned ahigher performance price ratio and must be widely used in highly corrosive oil and gas fields.

The corrosion of the gathering pipeline has become more and more serious because of its material In the environment of CO₂-Cl^--H₂O, strongly corrosive surrounding in the Tahe oilfield. The current corrosion situation was analyzed, as was the constitution of the produced water. The corrosion factor and anti-corrosion measures were studied. Combined with application practice of technology in the Tahe oilfield, countermeasures of pipeline repair are introduced. Suitability and economy of the technology in repairing gathering pipeline of oilfield are analyzed. Meanwhile, technical advantages of the technologies are summarized and improvement suggestions are proposed.

In connection with the types of geo-hazards constituted by karst effect to pipeline, this paper elaborates the evaluating calculation methods for the stability of karst top slab and estimation formula for the safe distance between karst cave and pipeline. The protection measures for pipeline in a karst area are put forward, including: diverting karst surface water, intercepting and blocking water inthe pipeline trench, over-crossing the form of the mouth of the karst cave, and reinforcement of the karst cave.

In the offshore natural gas pipeline transportation system, since the gathering and transportation pipeline system runs long time, wet natural gas gathering pipeline has been seriously corroded. The failure leakage accidents happen frequently, which cause great loss to the nation's economy and people's lives and property. Therefore, the corrosion research of the wet natural gas pipeline system has been a hot topic in recent years. There are no relevant standards or evaluation methods. The risk assessment of gathering and the transportation pipeline system face many problems. Based on the gray support vector machine, the paper starts from the gray relevant analysis, analyzes and researches the corrosion inspection data of the known gathering pipeline, establishes the corrosion rate prediction model of the wet natural gas gathering and transportation pipeline, and whose calculation results fit the actual value well compared with existing methods, which improves the prediction accuracy to some extent. It provides a new thought for the risk assessment, risk management, and maintenance research of the wet natural gas gathering and transportation pipeline, also has reference value for the quantitative assessment and integrity management of other long-distance oil and gas pipeline.

For the particularity of the harming object, the pipeline geohazards have their own characteristics; so, the monitoring methods for pipeline geohazards should also reflect their characteristics. Based on the investigation of geohazards along the Zhongxian-Wuhan natural gas pipeline and Sichuan-East natural gas pipelines, the volume distribution characteristics of landslides and unstable rocks along the pipelines were analyzed. A new scale classification is put forward in which landslides and unstable rocks are divided into four grades: small, medium, large and extra-large grade, respectively. The corresponding classification level indicator is 1/20 of the conventional landslides and 1/100 of the unstable rocks. This classification highlights the importance of small-scale geohazards along pipeline. According to the volume classification and combining with the risk rank of pipeline geohazards, a technical and method framework is put forward for pipeline geohazard monitoring. It reflects that no monitoring or only manual inspection is arranged for the small-scale, low-risk pipeline geohazards, while integrated monitoring, from ground surface to underground, from deformation to multiple fields, from disaster body to pipeline body, is considered to the large-scale, high-risk cases. This framework is beneficial for determining monitoring investment for pipeline manager, and choosing monitoring contents and methods for engineer.

Under the impact effect by flood, the floating and spanning pipeline will induce vortex-induced vibration phenomenon which is the main influence factor that severely threatens the pipeline's safety and stability. Taking an actual engineering problem as the background that one river-crossing pipeline which was eroded by flood and spanned over the river, and according to the fluid-solid interaction theory and the actual environmental condition of flood impact, a numerical model is established for the floating and spanning pipeline's vortex-induced vibration. The vibration response characteristics are discussed in different flood flow, and the limit flow of flood is analyzed on the condition that the pipe is safe and stable. The results show that free spanning pipeline presents obviously random vibration characteristics under the impact effect by flood. The pipeline's vibration model is basically the same in different flood flow, and the maximum displacement increases with flow rate. Transverse vibration frequency first increases and then decreases with the increase of flow rate. The limit flow of flood is between 320m³/s and 480m³/s when the given pipeline is in safety state. The analysis results can be used to predict the safety situation of pipeline running and give advice on flood hazard control, which has high engineering value.

According to the existing problems in the repair and reinforcement technique of composites during engineering application, and referring to the testing methods of composites and the corrosion resistance technique standard, this paper proposes a simple and feasible testing and evaluation system applied in the field application effect of the composite used in repairing and reinforcing of the pipeline. The evaluation results can be used by the manager as the rule to filter current repair and reinforcement materials and,consequently, improve the repair and reinforcement quality and prolonging the service life of the pipeline flow.

A pipeline is the main manner to transport oil and gas from one place to another. An oil-gas pipeline was built rapidly in the recent 10 years in China. At the same time, oil-gas pipeline accidents threaten peoples' lives and property. Corrosion is one of the main reasons affecting the oil-gas pipeline safety operation. A pipeline corrosion damage quantitative risk analysis was carried out on the basis of pipeline function equation and detecting data. The effect of the related parameters' uncertainty on the analysis results is resolved by the Monte-Carlo method. Then, the risk value of the pipeline segment is ascertained. It has significant meaning to the safety management of the oil-gas pipeline. A sample is given to show that: (1) pipeline corrosion damage risk analysis on the basis of the pipeline function equation and detecting data eliminates the subjective factor to assessment outcome and improves the objectivity of the risk analysis; (2) the Monte-Carlo method can resolve the problem of uncertainty of data, including operation parameter and detecting data; and (3) a pipeline with a defect can be kept safe by decreasing the operating pressure.

In this paper, inorganic disinfection by-products formation rules and amount in the process of combined disinfection of chlorine and chlorine dioxide were investigated in three kinds of commonly used pipe materials. We investigated two types of combined disinfection, which included: (1) adding chlorine first and then adding chlorine dioxide; and (2) adding chlorine and chlorine dioxide together with different proportions. Results indicated that chlorine levels were the highest in PVC pipe and lower in metal pipes for both kinds of combined disinfection. The difference between the two types of combined disinfection was that in the way of adding chlorine and chlorine dioxide together, chlorite levels in the ductile iron pipe increased with the increase of chlorine in the mixed disinfectant. While, for the way of adding chlorine first and then adding chlorine dioxide, chlorite levels were higher in ductile iron pipe than in stainless steel from the beginning to the end. The results would be a useful guide for many municipalities and communities using combined disinfection in determining disinfectant dosage, proportions of disinfectants and so on.

Harsh environments that may displace a given pipeline beyond the elastic limit include: seismic areas (that may be susceptible to soil liquefaction, fault displacement or soil instabilities), continuous or discontinuous permafrost (that may result in thaw settlement and frost heave), and construction. Then, strain aging generally occurs in steels which undergo a deformation process followed by thermal exposure. Under this background, the research of strain aging on X100 line pipe steels was developed. This paper introduces the development of X100 pipeline steels and focuses on the influence of strain aging on the mechanical properties of the base material. Line pipe mechanical properties of interest include: longitudinal and transverse yield strength, tensile strength, yield-to-tensile strength ratio, and Charpy impact energy. The main factors influencing the mechanical properties of interest include pre-strain and temperature. So, the effect of the law of strain aging on the mechanical properties of X100 pipeline steels can be clearly identified.

The demand of deep and peripheral resource exploration in old mines has been much more urgent as the shallow resource is lessening. The tunnel drilling exploration is a short-cut for deep resource exploration in an old mine. The use of explosives to dig tunnels is still the main tunnel exploration method in our country. This method is slow and the costs are high. Horizontal borehole wire line coring technology is efficient and labor-saving; it will be the main construction method of tunnel exploration. The difficulty which exists in the use of horizontal borehole wire line coring technology is the starting point of our study. The research and development of a high-speed drilling rig is introduced. The horizontal borehole wire line coring tools have characteristics such as the device to maintain concentricity of spearhead and composite position fixed structure. The inside tube can be segmented and removed. This introduces the key technology of the horizontal wire line coring technology. The experiment with this set of equipment is complete with a diameter of 78.5 mm and a depth of 401.8 m (horizontal hole). The coring rate reached 90.87%, validating the reliability and advancement of the technology and equipment.

The strain-hardening mechanism of high-strain line pipe was investigated and discussed in terms of microstructure and grain orientation. It is concluded that X70 high-strain line pipe does not fit to the Hollimon formula in the entire deforming process, but the normal X70 line pipe does. At the beginning of plastic deformation, the strain-hardening capacity of X70 high-strain line pipe is excellent. It decreases rapidly as the stain increases, then becomes stable after 2.0% total strain. The high-strain line pipe is composed of soft phase (polygonal ferrite) and hard phase (bainite). When plastic deformation initiates, the strain-hardening capacity of high-strain line pipe is better because of the ferrite deformation firstly ahead of the bainite, due to strain-hardening capacity of the ferrite is much better than that of the bainite. With ferrite deformation decreasing and bainite deformation increasing, the strain-hardening capacity declines until the micro-deformation is homogeneous. Besides, it is obvious that the large-angle grain boundaries of more than 15° are the majority of the microstructure of high-strain line pipe without deformation. So, the strain-hardening capacity is highest at the beginning of plastic deformation. As strain increases, the large angle grain boundaries decrease, and the small angle grain boundaries increase, then the strain-hardening capacity falls down. When the proportion of large angle grain boundaries and small angle grain boundaries becomes stable, the strain-hardening capacity is also stable.

Gas drainage borehole drilling efficiency is relied on for the performance of a gas drainage drilling rig. In this paper, an integrated model for a virtual prototype of drill rig is built first from the perspective of the rig's make-up, which is used for gas drainage in underground coal mines. This model consists of five sub-models which involve geometry, assembly, structural strength, hydraulic performance and multi-body dynamics. Then, an integrated design procedure for a drill rig is presented, and the virtual development environment is formed (which includes two modules of modelling and simulation). In the end, a case of directional drill rig ZDY6000LD (A) is given to demonstrate the proposed model and procedure. The stability of the stabilizer is analysed, and co-simulation of hydraulic and multi-body dynamics in the condition of directional drilling are also made. It has been shown that the virtual prototype is effective for the integrated design of an underground drill rig.

Honghe waxy crude oil, with 25¢C pour-point, is produced in northwest China. The cold atmospheric temperature in winter results in low soil temperature around shallow buried flow-line. It is hard, or even impossible, to pipeline Honghe oil in low ambient temperature. To pipeline high-pour-point crude oil, a lot of work has been done to match pour-point depressant (PPD) and Honghe oil. The pour-point can be reduced to 9¢C by a selected PPD agent, which improves the oil fluidities in both viscosity and yield strength. Not only can the length of shallow-buried flow-line connection wellheads and central plant be increased from less than 1 km to 3 km, but also the allowable shut-down time of shallow buried flow-line may be increased to 5 hours in winter, 22 hours in spring or autumn, and all day long in summer, respectively. As withtransportation length enlargement and shut-down time prolongation, the transfer stations that have to be used before PPD is adopted also can be eliminated and the transfer system becomes simpler and safer for buried flow-line to transport waxy crude oil.

Although the carrying capacity of the drilling fluid is an important factor for HDD crossing, it is not only a matter of drilling fluid. Some other factors are also related to it, such as the drillability of the stratum, types of the bit and the reamer, passes of the hole, mud pressure, velocity of the flow in annular space of the hole, the viscosity and gravity of the mud, and the size and gravity of the cuttings. It has not been mentioned until now, This paper explores the relationship among these factors and expects to make more successful HDD crossings.

On the basis of the design and construction experience of an existing mining under shallow cover tunnel project in water-rich soft stratum of China, this paper introduces the key and difficult design and construction issues of the mining under shallow cover tunnel combined with closed pipe-roofing protection method. The technical solutions to possible difficulties are proposed according to the in-depth investigation and study.

With the rapid popularization of trenchless technology, the application of horizontal directional drilling (HDD) technology for utility construction and other pipeline installation is seen more and more widely. The demand for HDD rig operators - both in quantity and quality - is accordingly increasing every day. Because the HDD project is always carried out beneath the ground, the operators will not observe the process of the project in real time, which leads to many accidents due to their lack of proficiency in HDD rig operating. As a result, it is necessary to train enough operators and improve their proficiency in operating the HDD rig to make sure the actual project can be completed successfully. Aimed to solve this problem, we have been developing the HDD rig operating system based on virtual reality for five years. At present, the VR (Virtual Reality)-based HDD rig operating system has been updated again. In accordance with the idea of existing system, we combined three dimension design software of Solidworks with the virtual reality compiling language of VRML (Virtual Reality Modeling Language) and visual programming language of Visual Basic to update the existing virtual rig training software system for the HDD rig operating. Then we designed and manufactured the hardware system to match the software system. It mainly includes a personal computer, the control levers and button switches of the real HDD rig operating console, an A/D acquisition card for signal collection and transformation, and a LCD (liquid crystal display) for displaying the drilling parameters. When the trainee operates control levers or button switches, the virtual HDD rig will make real-time response and the trainee will be able to observe all actions from various viewing angle and viewing distance. The updated system will help the trainee get most actual experience of operating real HDD rig.

Fiber-reinforced shotcrete has been widely used as part of permanent support during the last 20 years. Through the mechanical analysis oftheprinciple of steel fiber concrete structure, the applicability of steel fiber concrete in the permanent lining is researched. Combined with the typical anchor spray engineering, the reasonable proportion, tension, resistance of compression and shear of steel fiber spray concrete layer are completed by laboratory testing. According to the analysis of measured data of stress in wall rock, spray stress of concrete and level convergence in performance text of steel fiber shotcrete and its engineering application civil engineering, the stress distribution is more homogeneous and the yield capacity is better. When mixes the quantity by 0 increase to 1.2 kg/m3, fiber concretes 7d resistant to compression, the tensile strength and datum concretes compare, reduced 11.4% and the 8.7%, 28d intensity separately reduced 12.1% and 3.6%, and spotting spray experiment of civil engineering shows that the tensile strength and toughness of the steel fiber fiber concrete spray layer are higher than those of general one. The rebound of the steel fiber concrete is reduced. The results show that steel fiber shotcrete is perfect timbering material for permanent lining and it has wider application.

The technical advantage of directional drilling in coal mines is the trajectory controllability. The directional drilling trajectory algorithm derives drilling trajectory design parameters and systematically summarizes their criteria, which guides the design process. However, the optimization method of borehole trajectory design is a result of actual drilling.

The structural design of joints in highway culverts requires evaluation of expected values of both the shear force across the joint and the joint rotation that result from vehicle loads. This paper describes new design equations that have recently been developed for estimating shear force and rotation in bell and spigot joints for both rigid and flexible culverts. The equations are exact closed form solutions based on the modeling of the pipes as elastic beams, and the Winkler soil model (where the soil stiffness is represented using a series of elastic springs). The kinematic assumptions are explained and the equations are presented. Comparisons are included between estimates of joint rotations under surface loads and rotations measured during full-scale laboratory experiments. The paper concludes with a discussion of how shear force and rotation depend on pipe diameter, pipe stiffness and burial depth.

While a significant number of long-term sewer pipe and culvert failures result from joint leakage and erosion of backfill, there have been very few studies examining the behaviour of pipe joints. There is no established method for the design of bell and spigot or other joint types. Reported here, therefore, are test results on 600-mm diameter reinforced concrete, 900-mm diameter polyvinyl chloride, and 1500-mm diameter high density polyethylene pipes with gasketed bell and spigot joints. Full-scale live load tests on jointed pipe systems were conducted in the test facility at Queen's University, involving two different burial depths and three different surface load locations relative to the joints being evaluated. The experimental results are presented and assessed to determine the key demands generated at the joints and how they are influenced by the loading location, burial depth and pipe material. The different characteristics of soil-structure interaction for joints in rigid and flexible pipes are highlighted. Finally, joint performance in the laboratory is discussed in the context of the development of structural design methods for joints.

Ru River HDD crossing, one of the pipe installation projects of West-East Natural Gas Transmission Project II, involves sands and partly cobbles along the crossing path. Borehole stability plays a most critical role for project success. This paper's focus is on the evaluation of borehole stability based on both the project design document and geo-investigation data to support the HDD construction project. Ru River HDD crossing was designed to be 3300 m in drive length, 711 mm in diameter, and 42 m in cover depth. Geo-investigation provided soil lab testing data, including: soil description, density, void ratio, compression modulus, cohesion, internal friction angle and standard inertia coefficient. Soil arching, soil pressure, mud pressure, consolidation coefficient and dynamic disturbance resulted by reamer are taken into account to calculate the soil stability upper the borehole, believed to be the potential collapse point of the borehole. Then, the borehole stability at different depths of the Ru River HDD project was divided into five levels based on the calculation result and resistance range. Treatment ideas and suggestions were also put forward to decrease the risk of borehole instability of HDD crossing project.

The oil and gas pipeline failure database is comprised of many failure cases. Through failure, information gathering and analysis pipeline operators can find out the trend of failure occurrences and evaluate the performance of pipeline management. There are a number of institutions involved in failure data management. According to their managers, databases can be categorized as three types: 1) owned by one company, such as PetroChina, which collects and analyzes failure information in their own company; (2) managed by an authoritative management department that collects and analyzes failure information of companies under their responsibility, such as Pipeline & Hazardous Materials Safety Administration (PHMSA); (3) managed by an international group formed through cooperation and agreement between several countries and international companies who collect and analyze failure information of companies in the group, such as European Gas Pipeline Incident Data Group (EGIG). Failure in defining and information-gathering by different database managers is disscussed in this paper, which compares their failure rates and trends that are newly announced, as well. The failure of database management by PetroChina is emphasized by the author. Improvement of the database failure can be technically supportive for pipeline engineering critical assessments and would be important references for risk assessment, as the determination of failure probability and consequence are based on the statistical results. Failure incidents are precious wealth for companies, which can reveal the shortages of pipeline management and emergency rescue and enhance the operation safety.

The buckling of buried pipelines under external applied load is influenced by many factors. It may be caused by external pressure, internal pressure or axial force, and is very complicated. This paper studied the non-uniform buckling of a Φ660-mm × 7.1-mm pipe by FEM, the lost stability of steel, pipe form under different load, and the main cause of deformation were analyzed.

A submerged wall is the important protective structure which is constructed downstream of the pipeline as the oil and gas pipelines through the river. The invalidation of the submerged wall caused by the scour of flood impact will make the pipelines exposed or even cause to rupture. According to the characters of the submerged wall in the project of the long-distance pipeline, it concluded that the flood flow velocity, soil cohesion, angle of internal friction, gravity density of backfill, and the angle of friction between the earth and the wall back were random variables. This paper constructed the analysis model for the failure probability and the corresponding limiting condition equations of the submerged wall. Based on the theory of the Monte Carlo method and combined with the west-east gas pipeline crossing project, it calculated the failure probability of the anti-sliding and anti-overturning of the submerged wall. In addition, it also calculated the failure probability of the subsoil bearing capacity by taking the basal mean stress failure and the maximum compressive stress as a series system. This paper calculated the sensitivity of each of the random parameters under the different failure models, and compared the failure probability under different distribution of the soil parameters. The results show that the failure probability of the subsoil bearing capacity is the greatest when under the inducement of the flood. The flood-flow velocity is the main controlling factors of the three failure modes. The angle of internal friction has a big impact on the three failure modes. The distribution of the soil parameters has very little influence on the failure probability.

It is very dangerous for the safety of the pipeline which crossing the complex place where the geological disasters occurred frequently in the rainy season or by the influence of floods. Therefore, the mechanical response analysis of the pipeline which is influenced by the floods is essential. According to the actual stress state in the pipeline project and the relationship with the surrounding soil, this paper studies and builds the corresponding static and quasi-static response analytically format. Some specific examples were calculated and analyzed by the strain-based safety assessment criteria, and the most dangerous point was identified. The influence law of different diameters, internal pressure and the material of the pipeline to the pipe-stress was investigated. The results show that the mechanical model which was established in this paper coincides with the actual deflection and the analysis of the stress. The change of the diameter of the pipe is the most sensitive factor to the stress of the pipe which is influenced by the floods.

Much effort has been made to solve the running ductile fracture (RDF) arrest issue in the gas pipeline since RDF could cause a serious disaster. The Battelle two-curve model (BTCM), reformulated BTCM (RBTCM) and HLP Model (HLPM) seem to be the promising ways to solve the RDF arrest issue. In order to clarify the validity of BTCM, RBTCM and HLPM in the calculation of RDF velocity for Chinese modern X80 pipes, a full scale burst test was carried out. The RDF velocities were calculated based on BTCM, RBTCM, and HLPM, respectively. By comparing the calculation results with the experimental ones, it was found that the RBTCM shows the best fit with the experimental results. The possible reasons were discussed in this paper.

A systematic investigation of the effect of material inhomogeneity on pipe buckling is presented in this paper. The material properties of the pipe were obtained by a series of tensile tests. Numerical simulations were carried out to evaluate the effect of material inhomogeneity on pipe buckling. Post-buckling behavior was also simulated. This paper also explains the mechanism of cracking. The authors show how pipe buckling can be caused by weakened sections, and how both internal pressure and the ratio of diameter to thickness can significantly affect pipe buckling.

The quick coupler is the key component of the blind operation that the push rod and the plugging head need to be quickly connected and disconnected inside pipeline in near-pig receiver and launcher plugging operation process. The internal integrated hydraulic system controls the hydraulic circuit to switch on and off. In this paper, a new design scheme of quick coupler mechanism is put forward. It adopts the "point-to-point" design structure, which improves the reliability of the quick coupler in the process of blind operation. Based on the design requirements of push rod stability, the authors determined the structure size of the push rod and checked its reliability under all the operating conditions. The results show that when the push rod is under tension and compression loading, stress and strain of the push rod meet the requirements of working condition. Through the above research, the quick coupler provides technical support for the development of the near-pig receiver and launcher plugging work tools.

There was a directional well in China's western oil field with a depth of 3,000 m. Its casing ran from 139.7 x 7.72 mm J55 LC to 1852 m until the casing string fell off. The two short-section samples of failure were field end pin and the box and mill end pin. The sample geometric parameters and thread contour were measured using thread gauge and profilometer. Material chemical composition, mechanical properties and metallography of the sample were researched. According to the results of test, the main influencing factors of long round thread jump-out were analyzed by nonlinear finite element. One was the quality of thread itself, including thread parameters, the material properties and geometry dimension. The other was field casing running operation and make-up. The numerical simulation results were consistent with the field failure sample measured morphology. So, we knew that the main reasons for the jump-out failure were that the material yield strength of sample was less than the API5CT specified value, and field end pin make-up turns were short.

This study investigated the effects of orthophosphate, tripolyphosphate and hexametaphosphate on iron release control under the conditions of different sulphate concentrations in drinking water distribution systems. The results showed that all three kinds of phosphates had positive effects on controlling the iron release from corrosion scales in distribution systems. Tripolyphosphate was the most effective inhibitor on controlling the release of iron in bulk water, with the addition dosages of 0.50 mg/L and 0.25 mg/L acting better than that of 0.10 mg/L. Hexametaphosphate performed best on controlling color in bulk water, with the addition dosage of 0.10mg/L achieving the average reduction rate over 40%. Thus, hexametaphosphate was chosen as one kind of preferred inhibitor to iron release because the discolored water phenomenon in the tap could easily cause the customer complaints. Whatever the low (75 mg/L), the middle (150 mg/L) or the high (240 mg/L) concentrations of sulphate, adding different dosages of hexametaphosphate (0.10-0.50 mg/L) all had a significant controlling effect on iron release, with the average reduction rates of the total iron concentration, turbidity and color being 15% to 55%, 35% to 85% and 40% to 92% respectively. While stopping the addition of hexametaphosphate in bulk water in drinking water distribution systems under low-sulphate and mid-sulphate conditions, total iron concentration in bulk water slightly increased in first one or two days. It then returned to the low levels after 10 days. However, under high-sulphate conditions, the water quality in drinking water distribution systems deteriorated immediately after stopping hexametaphosphate and could not recover after 10 days.

The drainage pipe network plays a very important role that takes on the collection and transportation of wastewater in sewer system. The well status of drainage pipe network is necessary to guarantee better operation efficiency of a wastewater treatment plant. The study aims to estimate the influence of the drainage pipe network operation status on the influent of wastewater treatment plant (WWTP). The long-term and short-term and shock effect were investigated in the study. The result indicated that the influent wastewater component variation is obviously by the year and season rule in the long-term effect. The daily variation rule of wastewater quality and quantity is significant in the short-term effect. The shork effect is significant and the flow variation caused by rainfall became weak normally after 2-3 days of rain.

It is required that the working conditions of the flow should be regulated properly by valves during the operations management process of the long-distance water transmission. However, the accident of water hammer should be more likely to appear if the operation of the valve is inappropriate. The regulation of valve is turned up and turned down gradually to properly position lest the destructive water hammer should be produced. At this time, the valve is not operated until the hydraulic transient is stabilized so that the time of operation the first time is very long. If the time between the stable states is ascertained, the valve may be readjusted after stabilization of hydraulic transient to avoid destructive water hammer. The theoretical analysis which be deduced the stable time of the hydraulic transient during the flow regulations of the long-distance pipelines is reasonable and credible proven by dimensional analysis. Ascertaining the stable time of the hydraulic transient during the flow regulations of the long-distance pipelines can give a guidance of the valve operation and also ensure the security of the long-distance transmission water pipelines. This analysis method may be popularized to other long-distance water transmission projects.

The transportation technology of the An Yong oil pipeline is very complex, from the "3 ≤ 14" condensing tube accident in 2009, the problem of An Yong oil pipeline in the snow and the rainy season safely operating is the point that Pipeline Transport Company and Yan Chang Oil Group of Shaanxi focus and the technical problems which they will look forward to solving. By experiment, the solidifying point of oil heated and added depressant of An Yong oil pipeline evenly falls 10°C, which can essentially solve safely operating problem of An Yong oil pipeline being low throughput with wax to ensure that the pipeline does not condensate tube.