Geo-China 2016: Emerging Technologies in Tunnel Engineering, Modeling, Design, Construction, Repair, and Rehabilitation

Technical measures, such as underground partition wall, could sever as recourse to mitigate the ground movements induced by excavation. In this paper field monitoring and numerical analysis were used to examine the performance of underground jet-grouted partition wall in mitigating the effects of shield tunnel construction on existing pier of Xin-Zhong Road viaduct in the project of Changsha Subway Line 1 in China. The performance of the jet-grouted partition wall was calibrated by the reasonable agreement found between the observed field measurements and the numerical results. Underground jet-grouted-column partition wall was testified to serve as an effective measure in ground movement control given the need of tunnelling nearby piled structures.

With the rapid development of urban construction and the traffic congestion problems arise, underground engineering has developing rapidly throughout the country. The form of underground engineering is also more and more diverse. Numerical simulation method has become increasingly widely used in geotechnical engineering. However, when there are multiple excavation areas or channels and even intersections in a model, it will cause great inconvenience for modeling and calculation. To solve the modeling and calculation problem of complex models, Kriging interpolation method is improved to be suitable for geotechnical engineering. Kriging overlapping method of numerical simulation for complex models means that model is divided into a global model and a local model. Using Kriging interpolation method, the displacement of local model is lead to the global model as initial displacement field. And then further excavation for global model is carried out to get the final displacement field. Compared the results of numerical simulation and monitoring data, the results show that Kriging can consider spatial structure characteristics of the displacement field in underground engineering, and it has high reliability. As expected, the results of numerical simulation and measurement come to an agreement, which confirming the feasibility of Kriging overlapping method.

Excavation of urban-shallow buried tunnel would cause adverse effects on above or neighboring undergound pipelines, even leads to major accidents. According to the joint connection and deformation rigidity, municipal pipelines are divided into the flexible pipeline and the rigid pipeline. Based on the pipeline failure modes, safety criteria of various underground pipelines are discussed. Through the commonly accepted formula of soil movement induced by tunnelling, this paper proposes a simple method on safety evaluation of the flexible pipeline, and gives a case of engineering application, which takes into account spatial position relations between the pipeline and tunnelling, and deformation curve shape of the flexible pipeline. The calculation formula has fewer parameters to be used easily, especially suitable for quantitative safety prediction of underground pipelines in a condition that there are no enough formation datas and detailed pipeline informations before tunnelling. And it also provides a theoretical support for reasonably determining the limit alarming value of ground settlement in tunnel construction.

For satisfying the requirements of normal running and enlarged outer section in stabling line, parallel neighborhood metro tunnel with two different inner sections is adopted in Xi’an Urban Rail Transit Line One between North Zaoyuan Road and Hancheng Road. Based on the characteristics of different inner sections and small clear spacing, 2D-FEM was applied to simulate and analyze four construction schemes, of which shield method was adopted in left tunnel with small inner section and double-heading construction method or cross diaphragm method for right tunnel with large inner section. The results show that compared with the construction scheme that the tunnel with small inner section is firstly excavated, the larger tunnel by double-heading constructed is first accomplished can evidently reduce the disturbance effect on surrounding rock, reach better state mechanical of tunnel lining, in order to ensure safety construction.

In recent years, the theory and method of wavelet analysis is widely used in signal processing, pattern recognition, data compression, image processing, and quantum physics. Compared with modulus maxima, wavelet packet decomposition and coefficient shrinkage de-noising method of wavelet transform, their advantages and disadvantages are analysed and summarized, and their respective scopes are obtained. The Noissin chosen as the original signal with noise is analysed and de-noised by the modulus maxima method of wavelet transform, meanwhile the usage conditions and key computing parameters are also obtained. Finally, the modulus maxima method of wavelet transform are successfully adopted to de-noised the monitoring results of shield tunnel, the data revised are reliably provided for tunnel healthy diagnosis.

With more and more shield tunnels are constructed in highways and metro, the tunnel structure damages become a key problem that has important effect on the safe operation of the tunnels. In this paper, the possible damages of the shield tunnels during its service life are summarized based on the analyses of the influencing factors. The main damages of the shield tunnel include cracking and spalling of concrete, steel corrosion, deformation of tunnel lining’s collar joint or juncture-open and the leakage at segment, lining joint. On this bases, the reasons for these damages are discussed detailedly.

This paper describes a method for modelling the simulated transversely isotropic rocks. Series of physical and mechanical experiments have been used to obtain two materials A and B, which are chose to simulate rocks. Then the reasonableness of two materials are verified by comparing their properties to typical natural rocks. Based on this, a set of experimental apparatus has been developed for preparing the simulated transversely isotropic rocks. Uniaxial compressive tests are carried out to study the failure mode of the simulated rocks preliminarily. The results can provide a reference for researches in study of transversely isotropic rocks.

In order to improve the mechanical and deformation performance of surrounding rock and supporting structure in the construction of multi-partition excavation tunnel, and improve construction safety. Based on the tunnel construction mechanical properties and principle of orthogonal test design, multiple conditions three-dimensional numerical simulation study on construction space is carried out by finite element software for cross diaphragm with step method, CRD method and CD method applied to partial excavation tunnel commonly. Comparatively analyze response characteristics in aspect of crown settlement, surface displacement and supporting structure stress in different conditions, reveal influence rule about deformation and stress state of multi-partition excavation tunnel in different construction space. In the meantime, consider the maneuverability of the actual construction, then put forward reference comments to select reasonable construction space for multi-partition excavation tunnel, and the final purpose is to guide the construction.

The research on the waterproof failure mechanism was conducted by the software ABAQUS based on the project of waterproof design. The method used in the paper was compared with the predecessor method. The results showed that not only the predecessor method was workable but also the method in the paper was reasonable. The waterproof failure mechanism was also revealed. The research showed that the leakage was easier occurred on the contact surface of sealing gaskets under the condition of joint opening. However, the leakage was easier occurred on the contact surface of sealing gasket and concrete under the condition of joint dislocation.

A simplified computational model used for the stability analysis of the fillings is proposed based on the simplified Bishop method. In this model, sliding soil, circular slip surface, exterior load, pore water pressure and boundary constraint is defined by simplifying the complex system which consist of tunnel, filling materials and karst cave. The global stability coefficient of fillings is got by solving the equilibrium equation of force for individual soil slice and moment for failure mass and by assuming that the direction of inter-slice forces is horizontal. By this way, the risk of mud inrush due to the filled-typed karst caves can be identified. Using this analytical method, this paper analyzes a case and conducts research on the influence of hydraulic effect, shear strength parameters, mud content in cave and boundary constraint on the global stability of fillings.

The minimum rock cover thickness is a significant parameter during longitudinal section’s design of subsea tunnel by means of drilling and blasting. The thickness will impact the cost and safety when subsea tunnel is constructed. On the basis of numerous elasto-plasticity numerical tests and theoretical analysis, the minimum rock cover thickness’ criterion is provided, including minimum displacement method and factor of safety (FOS). For a certain section of subsea tunnel, with the growth of rock cover thickness, vault displacement will decrease first and then increase. There always exists a minimal value. At the same time, the same section is calculated and analyzed using a strength reduction method, and some clear regularities of subsea tunnel’s FOS are summarized. That is, for any section of a subsea tunnel, with the increasing of rock cover thickness, FOS increases first and then decreases, always with a maximum value. There is a close correlation between FOS and vault displacement’s variation tendencies. Accordingly, it can be thought that the technology feasible and economic reasonable minimum rock cover thickness is a rational and effective thickness, considering the maximum FOS and minimum vault displacement at the same time. Under this numerical method, the determined minimum rock cover thickness can give great reference values to the planning of tunnel’s vertical routes.

Under the condition of long-term action of groundwater table, especially in the karst area, tunnels diseases, especially seepage leakage and lining deterioration, which threatening the safety of traffic and tunnel structure, appear gradually due to the changing groundwater flow path around tunnels with atmospheric precipitation in the catchment area and physical and mechanical properties worsen of surrounding rocks and soils. How to prevent and treat the diseases effectively have become an urgent problem to be solved. A comprehensive strategy, with the example of the Pishuangao Tunnel on Beijing-Zhuhai Expressway, combined with ground surface, surrounding rock and the lining treatment, after architectonic geology, hydro- and engineering geology, geophysics and engineering geological survey, was adopted by the authors, and it achieved a satisfactory result after two years verification.

With the development and utilization of underground space in karst area, water-inrush is becoming a major geological disaster in tunnel engineering. The investigation for escape routes optimization after water inrush in process of karst tunnel excavation is particularly important. In the present study, a case of water inrush from the working face is investigated in a backward excavated karst tunnel. Numerical simulation is carried out by using the FLUENT software, the variation laws of velocity and pressure along with distance are analyzed and discussed by selecting a series of probing lines in a plane. Then flow characteristics of water after inrushing during double-line tunnel excavation are summarized. Finally, the optimized escape routes are made. The results show that: (1) the water velocity nearby the tunnel side wall is the minimum, while it is the maximum in the middle position. So people in tunnels should first move to the tunnel side wall and then escape quickly when water inrush happens. (2) The water pressure at the intersection area of the cross passage and tunnels is large. So people must not stay at the intersection area of the cross passage and tunnels when water inrush happens. (3) When water inrush happens in the left tunnel, if people meet the cross passage during escaping, they should pass through it rapidly, turn to the right tunnel and run to the entrance. (4) If there is not enough time to escape, people can run to the trolley and other equipment in the vicinity of the right tunnel working face. In addition, some rescuing equipment can be set up at the high location of the cross passage. (5) Even if large flow water inrush occurs in the tunnel, people can escape safely as long as the disaster is observed in time and the escape routes are optimized scientifically and rationally. The results are of important practical significance and engineering value to ensure the safety of tunnel construction.

With the rapid development of expressway construction, operating safety of tunnels gradually become prominent issues. It is necessary to garner more knowledge on characteristics of traffic accidents in expressway tunnels, which in favor of improving the safety of tunnels and reducing traffic accident rate of tunnel sections. Therefore, a study of traffic accidents from sixty-one tunnels of eleven expressways in Guangdong Province between January 2012 and June 2015 has been conducted. Then the distribution characteristics of traffic accidents are summarized respectively from the aspects of accident types, types of accident vehicles, seasons, annual variation trend, location, pavement type, skid resistance, alignment parameter, etc. The analysis results are helpful to formulate a reasonable operation strategy for tunnel traffic safety.

Based on a shield tunneling project using earth pressure balance (EPB) construction method in Tianjin, China, this paper builds a database of real monitored data which includes ground surface settlement at different phases of tunneling, chamber earth pressure, grouting pressure and volumes as well as excess pitch information. A model to determine the earth pressure in head chamber to maintain the face stability is proposed and verified with monitored data. Moreover, grouting volumes are analyzed and compared with different considerations.

Past studies have provided data on the variation of settlement distribution above relatively shallow tunnels in sands. There is, however, a lack of research that considers the case of relatively deep tunnels. This paper compares the results of a set of plane-strain centrifuge tests in dry dense sands. The cover-to-diameter ratio, C/D, of the tunnels ranged between 1.3 and 6.3, thereby including relatively shallow and deep tunnels. Ground movements are measured using an image-based measurement technique. Gaussian curves are fitted to the settlement data in order to evaluate the characteristics of the settlement profiles. An assessment of greenfield settlement trough shape, both at the surface and subsurface, is carried out. The effect that relative tunnel depth and volume loss has on the settlement trough shape is demonstrated and discussed. The results indicate a non-linear trend of settlement trough shape with C/D, which suggest a transition between shallow and deep tunnels within the investigated C/D range. To account for highlighted results, new relationships are proposed to estimate settlement trough shape parameters in dense sands.

The pipe roof reinforcement is usually used to stabilize the tunnel arch for tunneling in weak ground section or passing below highway. In this study, large scale pipe-roof (85m long and ϕ 159 mm) was used to enhance the Shitougang Tunnel where a railway tunnel passes below the Hengyang-Kunming Highway in China. The deformation of the pipe was measured by a series of strain gauges, and meanwhile, a three dimensional numerical analysis was carried out to investigate the mechanical performance of the long and larger pipe roof. The measured results are in good agreement with the numerical results. They both show that the stress distribution of the pipe roof can be divided into three sections: tension section ahead of tunnel face, compressive section behind the tunnel face and tension section near the entrance casing arch. The peak stress value occurs close to the entrance casing arch and a certain distance ahead and behind the tunnel face, respectively. This analysis illustrates the mechanical response of large and long pipe roof reinforcement used for a shallow tunnel passing below highway.

Damages due to a fault activity can be divided into dynamic rupture and quasi-static rupture. In some special projects like roads, channels, and pipelines, engineers have to design and construct them on the faults inescapably. In addition to seismic design, the effects of fault rupture crossing the structures must be considered in the design process. In this paper, four different computer models of a granular alluvium with and without tunnel were made by a three-dimensional finite-difference software. A normal fault offset with three different cross angles was applied to the bottom of the models at the next step. Then, the shear bands propagation and ground deformations were calculated. The results show that the effects of tunnel existence on the ground deformations and shear band propagation depend on the cross angle.

Cavity contraction method has been used for decades for the design of tunneling and the prediction of ground settlement, by modelling the cavity unloading process from the in-situ stress state. Analytical solutions of undrained cavity contraction in a unified state parameter model for clay and sand (CASM) are used in this paper to predict the soil behaviour around tunnels. CASM is a critical state soil model with two additional material constants, which has the ability to capture the overall behaviour of clay and sand under both drained and undrained loading conditions. Large-strain and effective stress analyses of cavity contraction provide the distributions of stress/strain within elastic and plastic regions around tunnels. The effects of ground condition and soil model parameters are investigated from the results of stress paths and cavity contraction curves. Comparisons are also provided between the predicted and measured behaviour of tunneling, using data of centrifuge tunnel test in clay. To account for the effect of free ground surface, Loganathan & Poulos’s method using undrained gap parameter is incorporated to estimate tunneling induced ground surface settlement.

This paper presents an investigation on the generation and distribution pattern of the temperature field within a vertical frozen soil wall by ADINA. The vertical freezing closure time was 7 days, and after a freezing time of 30 days, the vertical freezing formed a water-resistant frozen soil wall with a thickness greater than 1.6 m. The area within 1 m of the vertical frozen soil wall was affected due to the exchange of heat between the frozen and unfrozen zones. Thus, the spacing of vertical freezing pipes should be less than 1 m. For design of the freezing process, the effect of temperature at boundary zones should be taken into account. Marginal zones should be set aside because the effective/workable zone of freezing pipes is about 1 m. The width and depth of the vertical frozen wall should be larger than the designated sizes.

The off-shore immersed tunnel is placed at a varying level and consequently has to accommodate complicated foundation condition. The segmental type of tunnel is sensitive to the differential longitudinal settlement. Therefore, a number of ground improvement methods are considered in order to provide an appropriate foundation for the type of immersed tunnel in soft ground. The composite foundation method is one of techniques which can reduce settlement, increase bearing capacity and slope stability. The composite foundation methods included sand compaction pile (SCP), cement deep mixing (CDM), and jet grouting pile, etc. Based on the Island and Tunnel Project of Hong Kong-Zhuhai-Macao Bridge in China and the Busan-Geoje Fixed Link Project in South Korea, this paper describes design and construction in soft ground by the SCP method mainly for off-shore immersed tunnel foundation.

The excavation damaged/disturbed zone (EDZ) is significantly important for determining the loosening load of rock mass surrounding tunnel. While the main search was focused on the hard rock in the past, this paper presents a study on the soft ground of the longest subway tunnel constructed by subsurface excavation in China. Based on the damage constitutive laws, the method of numerical analysis was funded by finite element, which was validated by comparing with the laboratory tests. Some results can be concluded by numerical analysis. The EDZ of rock mass is an approximate circle around tunnel for the isotropic initial stress of the ground, and it will initiate when the ratio of stress release is more than 0.5. Besides, the EDZ would suddenly increase as the ratio of stress release is over 0.9. There will be an obvious stress concentration and deformation gradient in the EZD.

Pipe jacking force mainly consists of the penetration resistance from face pressure and the friction resistance between the pipe and surrounding soil. Jacking forces depends on following parameters: soil type, groundwater table, overburden, overcut, lubricant, stoppage, misalignment, length of drive, and intermediate jacking station (IJS). A slurry shield excavating through alluvium deposit to install a 1.5-m diameter sewer line was selected in many straight drives with similar conditions of groundwater table, overburden, overcut, and stoppage. The lubricant distributed among injection outlets along the pipeline ensures a more uniform distribution of lubricant around the jacked pipes and a more effective reduction in frictional resistance. This leaves the soil type and steering correction standing out to reduce the jacking force required. It can be concluded that the soil classification system developed in separate study helps interpreting the local variation of jacking force that is resulted from increasing penetration resistance due to either driving from coarse soil to fine soil or driving into wood log. This penetration resistance increment is recoverable when driving condition is reversed. The friction resistance increases significantly if misalignment is larger than a threshold value of 60 mm, and remains unchanged even if deviation is corrected. The misalignment effect on friction resistance is not recoverable. For large diameter pipe jacking with stabilized overcut and sufficient amounts of lubricant, the face resistance can be significant relative to the friction resistance.

The construction of urban metro in high-risk karst areas is different from that of highway or railway tunnel in many ways, such as having a great threat to the project stability, prone to induce secondary geological disaster, damaging the surrounding existing structures and being vulnerable. Based on the analysis of geological water level of internal and external tunnel project and various geophysical prospecting, it puts forward a method to explore the geological disaster seepage channel distribution regularity about urban metro in karst areas in an effective and accurate way. And the implementation and comprehensive analytic process concerning this method are covered in detail, which is exemplified by the geological disaster predication and seepage channel exploration of Yaman interval in urban Rail Line 1, Guiyang City. Then the key technology for comprehensive treatment towards seepage channel of karst tunnel is proposed and further verifying its effectiveness by utilizing numerical simulation software.

Collapse is one of the common disaster in tunnel construction. In order to ensure the construction safety of mountain tunnels, the attribute recognition model of risk assessment for tunnel collapse is established based on attribute mathematics theory. By the comprehensive analysis for influencing factors of the tunnel collapse, the surrounding rock grade, tunnel depth, angle of unsymmetrical pressure, rock mass integrity, earthquake, and the excavation span are selected as the indexes of the risk assessment attribute measurement functions were rigorously constructed to compute attribute measurement of single index and synthetic attribute measurement. The identification and classification of risk assessment of mountain tunnel samples were recognized by the confidence criterion. An exemplification study of a tunnel showed that the assessment results, obtained through attribute measurement analysis and the date of geological forecast agreed well, with the tunnel construction. This risk assessment methodology provides a powerful tool for systematically assessing the risk of tunnel collapse.

In order to improve the prediction methods of geological hazards in the front of a tunnel face. Gaussian process machine-learning is proposed and the classification model is established for advanced surrounding rock classification based on TSP-203 system. This approach extracts the useful information from the detection results of TSP-203, and establishes the quantitative index system of surrounding rock classification. Then the unknown nonlinear mapping between the detected geological information and the actual surrounding rock level is established by Gaussian process classification model (GPC) ultimately. To verify the feasibility and superiority, GPC model is applied to Jinpingyan Tunnel on Chenglan Railway in China and the results show that GPC performs a higher prediction accuracy than support vector machine (SVM) and grey clustering method in predicting surrounding rock level, providing a new approach for advanced surrounding rock classification.

This study integrates micro-seismic data and data from hundreds of rockbursts of different intensities that occurred in four deep headrace tunnels and one water drainage tunnel at Jinping II hydropower station in Sichuan province, China. The overburden of the studied tunnels is between 1900 m and 2525 m, largely excavated in marble. The tunnels have a total length of 12.4 km. The micro-seismic energy produced during the development of immediate rockbursts excavated with the drill-and-blast method (DBM) and a tunnel boring machine (TBM) were studied. The results indicated that the daily maximum micro-seismic energy can be used as a basis for estimating the rockburst intensity: no rockburst, weak rockbursts, moderate rockbursts, and intense rockbursts, and that the common logarithms of the micro-seismic energy of each level was <4, >4 and <5, >5 and <6, >6, respectively. For the same intensity, rockbursts excavated by TBM and DBM have the same range but different distribution characteristics. The micro-seismic energy can be used as a guide to establish a dynamic warning system based on the evolution of micro-seismic events to reduce the risk of immediate rockbursts during excavation of deep, hard-rock tunnels.

The impact of fault fracture zone on the stability of surrounding rock in tunnels is a key scientific topics of geologic engineering. In this study, a three-dimensional finite element model was established for Wuzhuling Tunnel of Zhuyong Highway in Zhejiang Province, China. By simulating the dynamic process of tunnel excavation through the fault fracture zone, the deforming performance and stress distribution law of surrounding rock were studied. It indicates that fault fracture zone in the tunnel reduced the stability of surrounding rock. When constructing tunnels in a fault fracture zone, three-dimensional numerical analysis can be performed to find the areas where collapse occurs easily. The study could provide useful information on the potential collapse areas for strengthening the engineering supporting structure and preventing the relative disaster.

Based on the project of deep foundation excavation of No. 15 Tianjian in Tianjin City, this paper used the finite element software to simulate the entire construction procedure from foundation excavation to applying the load of upper structure, and analyzing the effects of every step on open-cut tunnels of high-speed railway. The results show: the effects on tunnel of horizontal displacement are much greater than the vertical displacement during the deep foundation excavation; with the depth of excavation increasing, the horizontal displacement of the tunnel is much greater, and the tunnel will be leaned; however, after applying load of upper structure, the effects tend to be smaller; as a reinforcement measure, uplift pile can effectively limit the uplift of bottom soil, on the other hand it can reduce the effects on the tunnel during the foundation excavation.

A simple approach to predict the settlement of ground surface during the construction of metro tunneling using pile-beam-arch (PBA) method, subjected to pore pressure is presented. As to the analysis on the response of a single pile installed beneath the tunnel, a softening nonlinear model was adopted to predict the relationship between unit skin friction and pile-soil relative displacement developed along the pile-soil interface and a bilinear base load-displacement model was used to predict the relationship developed at the pile end. To analyze the settlement of ground surface during the construction of metro tunneling using PBA method, a highly effective iterative computer program was developed. In order to demonstrate the effectiveness and accuracy of the proposed simple method in this paper, the result is compared with one well-instrumented previous test. The proposed simple analytical approach is economical and efficient, and suitable for the analysis of the settlement of ground surface during the construction of metro tunneling using pile-beam-arch (PBA) method subjected to pore pressure.

The traditional modification factor approach employed to evaluate the building movements due to tunneling is for plane-strain situation. Such approach could not cater for the effect of building dimension along the tunnel axis. In the present study, three-dimensional finite element analyses were conducted to determine the movements of buildings with various plan dimensions and locations induced by tunneling. A new modification factor is proposed to cater for the true three-dimensional nature of the problem. A relationship between the new modification factor and building bending stiffness is proposed to determine the relative movement between the shallow foundation and Greenfield ground settlement due to tunneling.

In urban areas it is often required to assess the deformation distributions induced by tunnel construction on piled buildings. In this paper, a simple analysis method is presented for estimating these deformations. The proposed method is based on a two-stage procedure: (1) estimation of the greenfield ground movements caused by the tunnel excavation, and (2) analysis of the foundation/building on elastic springs subjected to a system of forces induced by the greenfield ground movements. Simple closed-form expressions are used for the evaluation of spring stiffnesses and tunnelling-induced forces. The proposed method is validated by comparing its predictions with those from 3D finite element analyses. It is shown that the simplified analysis method provides a good assessment of building deformations for several cases of tunnelling beneath piles and relative soil-structure stiffnesses. The proposed method represents a useful tool for preliminary parametric analyses due to the reduced computational cost and simple yet versatile implementation compared to 3D numerical analyses.

Buttress and cross-wall have been widely adopted with success in soft ground excavation work. The interaction between the soil, buttress/cross-wall and diaphragm wall is a three dimensional (3D) problem but in practice the problem is commonly simplified into a two-dimensional problem. This study compared the contribution of buttress and cross-wall on the displacement of diaphragm wall via a series of 3D finite element (FE) analysis. The numerical procedure was first calibrated against the field data obtained from a 16 m deep excavation project in Taipei City. The model was then used in the subsequent parametric study to evaluate the efficiency of buttress and cross-wall for a diaphragm wall supported excavation. Result showed that cross-wall and buttress were equally efficient in restraining the lateral displacement of diaphragm wall.

To mitigate heavy traffic in Bangkok, a cut-and-cover tunnel is often constructed at a congested intersection beneath an existing overpass. The effects of stress relief due to long and narrow excavation can cause adverse impact on deep foundation and super structure of the overpass. However, this adverse impact is still not fully understood. To evaluate the tunnel-pile interaction, measured and back-analyzed data collected from a cut-and-cover tunnel construction across beneath an adjacent flyover is interpreted. The tunnel was supported by diaphragm wall, designed for 7 m deep excavation in thick soft clay. Bored piles supported the overpass are located about 8 m away from the diaphragm wall. Numbers of instruments were installed to observe ground and structural responses due to the excavation. Interaction between the cut-and-cover tunnel and deep foundation of the overpass was back-analyzed using finite element method. For numerical simulation, an advanced hardening soil model with small strain stiffness was adopted. Effects of construction time on movement of diaphragm wall was modeled and compared with the measured results. Difficulties and practical construction method adopted under the existing flyover are discussed. Back-analyzed responses of force in piles, movement and stress in soil due to excavation and construction time are reported.