Journal of Pipeline Systems Engineering and Practice

Pipeline suspension bridges are narrow and wind sensitive. There is a lack of research on the mechanical performance of pipeline suspension bridges under wind load, especially under the action of gorge wind. This paper studies the aerodynamic stability of the typical pipeline suspension bridge under the action of wind load by conducting a wind tunnel test of a full-bridge aeroelastic model. Setting a $\pi$ connection to replace and simulate the core beam stiffness avoids the impact of the core beam on the flow pattern of wind, making the wind-induced dynamic response results obtained from the test more like the practical situation. The results of the measurements of the model dynamical characteristics indicate that the structural dynamic characteristics of the full-bridge aeroelastic model is similar to that of the prototype. The test results show that under various operating conditions, the typical pipeline suspension bridge in the paper has sufficient aerodynamic stability in both a boundary-layer wind field and a turbulent flow field. Under various testing conditions and wind speeds, no flutter, galloping, or other aerodynamic instabilities occur, and no lateral deformation, divergent torsion, or other static instabilities occur. There are no clear vortex-induced vibrations in the lateral, vertical, and torsional directions of the model main beam.

Currently it is not possible to fully assess the risks to human health and wellbeing from contaminant intrusion into drinking water distribution systems due to lack of understanding and accurate estimation of intrusion volumes during dynamic pressure events. This paper presents results quantifying such volumes from carefully controlled but representative physical three-dimensional experiments. Results show how the volumes change as a function of the dynamics of the driving pressure and how these volumes can be estimated from the time integral of the measured driving head. Results also reveal the complex coupling of dynamic pressure behavior interacting with the leak orifice and the exchanged volumes. The findings of this work can be integrated within assessment frameworks to enable better estimation of intrusion volumes and hence management of risk to public health.

Buried structures, such as pipes and culverts, are extensively used for transportation applications. The existence of these structures within the soil mass causes a redistribution of stresses. The stiffness of the buried structure relative to the surrounding soil affects the magnitude and distribution of vertical stresses. Higher stresses on a buried structure may cause excessive deformations and even failure of the buried structure. Expanded polystyrene (EPS) geofoam, a lightweight material, has been increasingly used above buried structures as a compressible inclusion to reduce vertical stresses acting on the buried structures. This experimental study investigated the effects of EPS geofoam, including geofoam stiffness and thickness, on the distribution of vertical stresses above a rectangular concrete culvert under static and cyclic footing loads. Reduced-scale models were constructed in a test box under a plane-strain condition. This study adopted the induced trench installation (ITI) method to place the concrete culvert overlaid with an EPS geofoam. The backfill material was a dry, poorly graded Kansas River sand. The footing load was applied parallell to the culvert axis. Earth pressure cells were used to monitor the vertical stress distributions above the geofoam and surrounding soil. The experimental results show that the EPS geofoam reduced the vertical stresses on the buried structure due to the mobilization of soil arching. The lower stiffness and thin geofoam had more effect on the vertical stress reduction. Cyclic loading minimized the soil arching effect induced by the compressible geofoam. This paper also examines the test results with available analytical solutions. The effects of soil arching and the induced vertical stress above the rigid structure under static footing load were considered separately. The analytical solutions were found to match well with the experimental results.

In view of the nonuniform landslide driving force in practical cases and the common landslide–pipeline separation phenomenon, a new pipeline–soil separation model under the action of a parabolic landslide driving force is proposed in this paper, and the closed analytical solutions for this model are derived based on elastic foundation theory. Moreover, the case of a long transportation pipeline crossing the Luozhentian landslide was studied using the analytical method, and comparisons between the analytical results and finite-element method (FEM) results are also made to validate the exactitude of the analytical solutions. In addition, the deflection and stress results of the pipeline in different conditions were also compared, and influences of the calculation parameters on pipelines were analyzed. Three conclusions can be drawn: (1) the deflection and stress of the pipeline increase remarkably along with the growth of length of the separation section; (2) the deflection and stress of the pipeline increase along with the growth of |$\lambda$|, which reflects the nonuniform degree of the parabolic driving force; (3) the deflection of the pipeline decreases slightly with the growth of the resistance coefficient $k$ of the landslide soil, whereas the stress changes nonmonotonously; and (4) the deflection and stress of the pipeline slightly decrease with the growth of the lengths of pipeline crossing the landslide, and the maximum deflection of pipeline increases with the growth of the proportion $\mathrm{\Omega }$.

Sewer pipelines are a major component of any infrastructure. In fact, they are subject to deterioration through their service lives. Although researchers are pointing out the consequences of erosion voids in sewer pipelines, the literature lacks the evaluation and prediction of such a defect. This research’s main goal is to propose a model that can predict the condition of the erosion voids present outside sewer pipelines considering the fuzzy expert system. The methodology relies on different factors that are expected to contribute to the voids’ development and severity. Fuzzy membership functions are constructed for five identified factors. The aggregated index representing the condition of the studied defect is achieved by considering the relative weights of the factors collected from 32 experts. The model is implemented on two case studies. The first case study supplied average values of accuracy, precision, and true positive rate (TPR) of 83%, 80%, and 76%, respectively. The second case is used to associate the soil intrusion defect with the erosion voids condition. Accordingly, it concludes that higher soil intrusion percentages are observed in poor and critical erosion voids conditions. In addition, a regression analysis model is developed to study the relation between the structural grade of sewer pipelines and erosion voids conditions. The regression model produced a coefficient of determination (${\mathit{R}}^2$) of 70.0%, minimal errors, and a high average validity percentage (AVP). This research shall help decision-makers in studying erosion voids defect to avoid major rehabilitation costs and sinkholes.

Polyethylene pressure pipes are designed for service lives of at least 50 years. While so far lifetimes have been assessed by pipe pressure tests, due to improved slow crack growth (SCG) resistance and increased testing times such tests are not suitable anymore for modern pipe grades. The paper presents an alternative methodology for lifetime prediction, combining practical advantages of the cyclic cracked round bar (CRB) test and linear elastic fracture mechanics. A major advantage of this procedure is that material characterization is done at ambient temperatures. The key challenge in this context is to measure SCG rates in CRB specimens. After determination of crack kinetics at different dynamic loading ratios, material laws for SCG at static loading are extrapolated. Based on the stress intensity factor concept and realistic considerations of initial defect size and changing crack front geometry, pipe lifetimes of four different PE pipe grades are predicted. The results show that for all materials the required minimum lifetime of 50 years will be reached and under practical assumptions even 100 years will be exceeded.

Lightweight materials such as expanded shale/clay/slate or tufts and slag are used in the construction of rigid culverts to mitigate high earth loads and settlements. However, the cost of using lightweight aggregate can be high compared with using normal-weight backfill. In the design and construction of induced trench culverts, lightweight waste materials such as sawdust, wood chips, and tire-derived aggregates (TDAs) have been successfully used. One of the concerns with the use of sawdust and wood chips is their high compressibility and possible degradation over long design life. In the case of thick zones of tire-derived aggregates, generation of heat and fire hazard are regarded as disadvantages. To address the concerns pertaining to the high cost of lightweight aggregate and the use of thick zones of TDA, the use of lightweight aggregate mixed with TDA is presented in this paper. A laboratory testing program determines the geotechnical properties of expanded shale lightweight aggregate, tire-derived aggregate, and their mixtures using a large direct shear box, one-dimensional compression testing equipment, and a split-ring apparatus. Various mixtures are evaluated for shear strength, compressibility, and coefficient of earth pressure at rest.

Gasketed bell and spigot joints in flexible pipelines are expected to be subjected to shear force, diameter change (or ovalization), and rotation under field conditions. Nonetheless, only some of these demands and their combinations are examined by current quality control tests employed in North America. This study was undertaken to examine the response of gasketed bell and spigot joints in 300-mm high-density polyethylene (HDPE) pipelines when subjected to combinations of expected field demands under internal or external pressure, employing a recently developed test apparatus and pressure system. It was observed that expected field magnitudes of shear forces and diameter change applied across the joint influenced its ability to remain leak tight. Medium-term tests were also examined to assess the influence of the time-dependent response exhibited by the HDPE and rubber. It was observed that joint leakage resistance was influenced; this was attributed to the rearrangement of the joint components during the test period.

Three analytical methods are used to evaluate the lateral buckle capacity of perfectly straight pipelines supported by a seafloor foundation: the beam-on-elastic-foundation method, the Kerr thermal buckling method, and the Rayleigh-Ritz method. These analytical methods and a numerical finite element method including the pipeline out-of-straightness characteristics are used to investigate the design space for pipeline buckling through deterministic and Monte Carlo investigations of a typical condition. A regression model is fitted to finite element results and then used to predict responses for other general conditions. Characteristics of observed pipeline out-of-straightness are described and their influence on its buckle capacity is examined. Bounds to the expected pipeline buckle capacity may be established using the four analysis methods.

Routing utility conduits underneath buildings is not always an avoidable situation, especially in densely populated and congested urban centers. Placing the pipe at a shallow depth attracts substantial additional earth pressures and loads causing overstressing and/or unacceptable deformations of the buried pipe. The backfill material characteristics control the pipe-soil interaction mechanism and sequentially the amount of exerted pressures. Tire-derived aggregate (TDA) is an engineered construction, lightweight backfilling material produced from recycled scrap tires. In the literature, TDA is often referred to as tire chips or tire shreds. TDA has excellent geotechnical properties, maintains its structural integrity, and weighs 50–60% less than conventional earth fill. In this paper, two full-scale field tests were conducted to evaluate the usefulness of using a layer of TDA above existing metal pipes to enhance the stress arching mechanism (i.e., stress bridging). In addition, the complicated pipe-soil interaction was investigated by monitoring the surface settlement, change of the pipe’s wall strains, and the pressure distribution over and around the pipe. The field results showed that using a layer of TDA over the pipe is significantly effective in reducing the pipe’s stresses and the magnitude of transferred pressures compared to using conventional backfill. Furthermore, three-dimensional finite element models (FEM) of the tests were developed to study the interaction mechanism of the considered problem, in which the developed models were validated against the field tests results. An excellent agreement was observed between the measured pipe’s strain values and surface settlements and the numerically obtained results. Additionally, an extensive parametric study was conducted to examine the effect of changing some key parameters on the performance of the investigated system (i.e., the thickness of the TDA layer, shape and configuration of the TDA cross section, and the pipe’s stiffness). This study illustrated that using a layer of TDA backfill above preexisting buried pipes is an excellent construction alternative to enhance the stress bridging mechanism under static loading conditions. The proposed system may lead to avoiding the costly pipeline rerouting option when there is a need for building over preexisting pipes.

Natural gas is generally transmitted from production to consumption areas through an infrastructure of pipelines consisting of three separate networks, namely transmission, feeding, and distribution. The transmission network delivers high-pressure gas near the main consumption areas, and feeding and distribution networks reduce the gas pressure in two stages through city gate stations (CGS) and town board stations (TBS) before delivering it to consumers. An urban gas network consists of feeding and distribution networks. The present study proposes a mathematical model for the topology design of an urban gas network. The model determines topology and capacities for the TBS of the network having the least possible cost. An algorithm is presented for small-network problems to obtain the diameters of the network pipes taking into account the pressure and velocity constraints of the gas networks. In addition, a hybrid ant colony algorithm is proposed for solving large-network problems. Finally, the applicability of the proposed model and proposed algorithms are assessed in a case study.

Lightweight fill materials are being increasingly used as a construction material for enhanced construction operations featuring construction on soft ground, in cold regions, and in earthen structures and above buried pipes/culverts. Extensive studies were performed in the last decade on a wide variety of lightweight fill materials used in construction practices. One such material is expanded polystyrene (EPS) geofoam, which has been used as a geotechnical material since the 1960s. This research paper presents EPS geofoam characterization through laboratory and field investigations and enhances the understanding of this material to reduce the performance disparity between the laboratory and the field. The laboratory characterization studies involved evaluation of densities, stiffness, and unconfined compressive strength (UCS). The field characterization studies involved evaluating stress distribution by instrumenting the EPS geofoam with pressure cells. It was observed that the stress distribution in the EPS 22 geofoam material was different from that determined by the methods published in the literature. This paper highlights the comprehensive analysis of material characterization and behavior of EPS 22 geofoam under laboratory and field conditions.

Pipeline construction in open trenches requires an appropriate degree of compaction of the soil around and below the springline, and especially in the haunches area, to ensure embedment on the contact surface of the trench. However, due to the lack of space in many inner-city areas with large numbers of different pipes crossing each other, it can sometimes be difficult in practice to carry out a proper soil compaction in accordance with regulations. This in turn may lead to damage, not only to the newly installed pipe but also to surrounding pipes. There are various innovative materials available to effectively provide proper embedment, and one cost-effective alternative is the use of expandable polystyrol (EPS) bedding materials. These prefabricated sections of hard foam are specially tailored to fit different types of pipe. They substitute for soil in the haunches area to ensure an optimized degree of embedment. In addition, it is possible to install two pipes on top of each other using EPS, which greatly reduces the amount of excavated soil required for backfill. The lightweight construction also simplifies handling on site. This paper presents an examination of the state-of-the-art on the use of EPS bedding materials in pipeline installation, focusing on their mechanical properties, quality control and durability against chemical, physical, and biological environmental impacts. The long-term behavior of installed EPS materials and the possibility of their use on several construction sites are assessed. In addition, using finite-element calculations, stress and deformation of installed EPS material with particular regard to creeping and buoyancy effects are investigated. Finally, the results from the product tests, experimental results and calculations, together with recommendations for their practical application are presented.

Prior video technologies such as closed-circuit television (CCTV) cameras have been used for culvert inspection. They are limited by the range of the area scanned and by the direction in which the camera is oriented because of a limited field of view (FOV). In this research, a 360-degree camera mounted on a remote-controlled crawler was designed and modified to travel through a culvert to scan and take videos of the culvert’s interiors. With the unique mounting and coverage of the 360-degree camera, a continuous view of the inner walls of the culvert was captured, as if by a human eye, making visual inspection of hard-to-reach areas possible. The video was analyzed manually, and areas suggesting defects were studied. Snapshots of defective areas were further analyzed using computer software developed in-house, where defects were identified by differences in color and texture. Calculations made from the data collected helped to pinpoint the location of the defects within the culvert and estimate the area of the defects in order to provide culvert inspectors with quantitative information on the condition of the infrastructure.

An odometer is an important part of a pipeline inspection gauge (pig) for measuring distance and defining the position of pipeline defects. Due to the peculiarity of their construction, odometers are prone to unbounded cumulative errors during pigging, and the weld is the main reason for this type of error. As a result, research on the odometer’s motion when passing over a weld is essential for improving its accuracy and has attracted much more attention than before. In this paper, the trajectory of an odometer crossing over a weld was directly observed by a high-speed camera, and different trajectories with variations in translational velocity were proposed based on the experimental results. The effects of translational velocity, pretightening force, and spring rate on the odometer’s trajectory were investigated. Experimental results indicate that a bouncing phenomenon occurred at a high translational velocity. A secondary jump, third jump, and even more jumps can be observed with increments of translational velocity. High pigging velocity can increase odometer error due to a serious collision, but this error can be restrained by a large pretightening force. Compared with the translational velocity and pretightening force, the spring rate has almost no influence on the odometer’s error due to limited spring compression. Research results in this paper can provide better understanding of the motion of the odometer and contribute to finding a way to improve the accuracy of the odometer wheel system.