scholarly journals Investigation on the Influence Caused by Shield Tunneling: WSN Monitoring and Numerical Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hao Liu ◽  
Jinjiang Shi ◽  
Jiasen Li ◽  
Chao Liu
Keyword(s):  
Signal Transmission ◽  
Monitoring Data ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Wireless Monitoring ◽  
Mems Sensor ◽  
Grouting Pressure ◽  
Transmission Test

Traditional monitoring techniques are faced with the problems of low acquisition frequency and easy to be affected by the construction environment during the shield tunneling, which cannot meet the actual needs of timeliness monitoring of surrounding environmental impact on shield tunnel construction. Based on this actual demand, a wireless sensor network (WSN) system was used to monitor the response of shield tunnel segments and surrounding buildings during the shield tunneling in this study. According to the result of the signal transmission test, an optimization scheme of microelectromechanical system (MEMS) sensor layout is designed to improve the monitoring efficiency of the WSN system. Through the comparative analysis of WSN system monitoring data and traditional monitoring data, it is found that, with the increasing distance between the monitoring section and the tunnel face, the convergence value of tunnel lining clearance gradually tends to be stable, and the wireless monitoring results of transverse clearance convergence of the tunnel in this section are consistent with the overall deformation trend of the convergence gauge monitoring results. This study also simulated the shield tunneling adjacent buildings using a nonlinear finite element method. A parameter sensitivity analysis of the support pressure of the excavation face and the grouting pressure at the tail of the shield is carried out. The results show that the surface settlement can be reduced by properly increasing the grouting pressure and the support pressure of the excavation face. Moreover, increasing the support pressure of the excavation face has a better inhibition effect on the settlement of the surface soil than increasing the grouting pressure.

Analysis on Segment Floating in the Construction of Large-Diameter Crossing-River Shield Tunnel

2015 ◽  
Vol 724 ◽  
pp. 17-21
Author(s):  
Run Lai Zhang ◽  
Li Ming Tang ◽  
Kun Tang
Keyword(s):  
Frictional Force ◽  
Large Diameter ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Factors Affecting ◽  
Grouting Pressure ◽  
Rapid Setting ◽  
Grouting Material ◽  
Longitudinal Stiffness ◽  
Initial Solidification

Segment floating is a common problem met in the construction of large-diameter crossing-river shield tunnel. The factors affecting segment floating are discussed first and analyzed by numerical simulation, including the properties of grouting material, the speed of shield tunneling, grouting pressure difference, the tunnel longitudinal stiffness, frictional force between segment rings and weight of the supporting system. The simulation results indicate that segment floating will reduce by shortening slurry’s initial solidification time, slowing shielding speed, improving the tunnel longitudinal stiffness as well as increasing the frictional force between segment rings. And some measures are given such as applying new rapid-setting slurries, shear pins, rubber mats with high friction coefficient and pre-stressed bolts

Three Dimensional Numerical Analysis of Ground Settlement Induced by Shield Tunneling

2012 ◽  
Vol 182-183 ◽  
pp. 937-940
Author(s):  
Zhong Chang Wang
Keyword(s):  
Soil Layer ◽  
Three Dimensional ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Ground Subsidence ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Maximum Settlement

The fine numerical simulation is used to study the ground settlement of complex stratum owing to shield construction by ANSYS program. It is shown that the closer the distance between soil layer and the axis of tunnel is, the smaller the disturbance of construction is, the obvious the ground surface settlement is. The value of the maximum settlement at the center of the surface is 7.4mm. The maximum settlement of vault is 14mm. The ground subsidence in cross section distribution is shaped of normal distribution. The closer the distance between soil layer and ground surface is, the smaller the vertical displacement is, the bigger the width of settlement trough of soil layers is. The width of settlement trough is 25m. The volume loss rate of shield tunnel is about 0.32%. The width coefficient of ground settlement trough is 0.56. The tendency of ground settlement decrease to become gentle with the advance of shield construction. The ground settlement keeps constant after tunnel face advancing to 30m.

Shield Tunneling Parameters Optimization Based on Dynamic Bayesian Networks

2014 ◽  
Vol 941-944 ◽  
pp. 921-927
Author(s):  
Tie Mei Zeng ◽  
Bao Jun Ding ◽  
Yan Hong Wang ◽  
Li Mao Zhang
Keyword(s):  
Optimization Method ◽  
Dynamic Bayesian Networks ◽  
Surface Subsidence ◽  
Parameters Optimization ◽  
Monitoring Data ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Parameter Learning ◽  
Shield Tunneling ◽  
Network Nodes

To control the surface subsidence in shield tunnel construction, a DBN-based, parameters optimization method was proposed and applied to a tunnel project in Wuhan, China. Selected the construction parameters to optimize as network nodes and set discretizing rules to determine the nodes domain, then discretized monitoring data and applied them to parameter learning to obtain complete DBN model. This model was validated with engineering measured data , then applied it to determine the setting optimal operating-range of each parameters and within that optimized the parameters real-timely according to the monitoring data changing. The results show that this model can reflect the inner link between the surface subsidence and shield construction parameters and this DBN-based method can control the surface subsidence in shield tunnel construction effectively.

scholarly journals Upper Bound Solution for the Face Stability of Shield Tunnel below the Water Table

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Xilin Lu ◽  
Haoran Wang ◽  
Maosong Huang
Keyword(s):  
Upper Bound ◽  
Limit Analysis ◽  
Fe Simulation ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Seepage Force ◽  
Tunnel Face ◽  
Face Stability ◽  
The Face ◽  
Upper Bound Limit Analysis

By FE simulation with Mohr-Coulomb perfect elastoplasticity model, the relationship between the support pressure and displacement of the shield tunnel face was obtained. According to the plastic strain distribution at collapse state, an appropriate failure mechanism was proposed for upper bound limit analysis, and the formula to calculate the limit support pressure was deduced. The limit support pressure was rearranged to be the summation of soil cohesionc, surcharge loadq, and soil gravityγmultiplied by their corresponding coefficientsNc,Nq, andNγ, and parametric studies were carried out on these coefficients. In order to consider the influence of seepage on the face stability, the pore water pressure distribution and the seepage force on the tunnel face were obtained by FE simulation. After adding the power of seepage force into the equation of the upper bound limit analysis, the total limit support pressure for stabilizing the tunnel face under seepage condition was obtained. The total limit support pressure was shown to increase almost linearly with the water table.

scholarly journals Face Stability Analysis of Shield Tunnel Using Slip Line Method

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Weiping Liu ◽  
Shaofeng Wan ◽  
Xinqiang Song ◽  
Mingfu Fu ◽  
Lina Hu
Keyword(s):  
Stability Analysis ◽  
Slip Line ◽  
Yield Criterion ◽  
Limit Equilibrium ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Tunnel Face ◽  
Face Stability ◽  
Line Method ◽  
The Stability

The sufficient support pressure is essential to guarantee the safe construction of shield tunnel. Thus, it is necessary to analyze the stability and assess the limit support pressure of the tunnel face. The main methods for face stability analysis mostly focused on finite element method, limit equilibrium method, and numerical simulation method. In this paper, the slip line method is applied to analyze the stability of the tunnel face. The soil is supposed as ideal isotropic, homogeneous, and incompressible continuous material, which obeys the Mohr–Coulomb yield criterion. A mathematical model of the limit equilibrium boundary value problem is established. The slip line method is used to solve the slip line field and stress field of the soil behind the tunnel face. Limit support pressure and failure mechanism of the tunnel face are then obtained. In addition, comparisons between the results of this study and those of existing approach are performed, and the influence factors are also discussed. The results show that the slip line method is proven to be reliable for the evaluation of limit support pressure of the tunnel face stability.

scholarly journals Three-Dimensional Discrete Element Analysis on Tunnel Face Instability in Cobbles Using Ellipsoidal Particles

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3347
Author(s):  
Chao Liu ◽  
Liufeng Pan ◽  
Fei Wang ◽  
Zixin Zhang ◽  
Jie Cui ◽  
...  
Keyword(s):  
Model Test ◽  
Discrete Element ◽  
Soil Disturbance ◽  
Triaxial Tests ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Element Analysis ◽  
Micro Scale ◽  
Dem Simulations

Soil disturbance has always been the major concern in shield tunneling activity. This paper presents the investigation on the micro-scale responses of the soils during shield tunnel excavation in sandy-cobble stratum. The code paraEllip3d is employed in discrete element method (DEM) analysis in which the soils are mimicked as an assembly of ellipsoids. Triaxial tests on the micro-scale responses of cobbles are carried out using the materials sampled from the tunnel face during construction period, and corresponding DEM simulations are performed to calibrate the micro parameters for the ellipsoids. On this basis, the face instability process during the shield tunneling in cobbles is studied using 1 g model test as well as corresponding DEM simulation. The micro-scale responses of cobbles are investigated by triaxial test as well as corresponding DEM simulations. Multiple material responses are discussed in the DEM simulations, including the stress–strain relationship, the contact distribution, and the force chain evolution in the elementary and model test. Finally, the mechanism of tunnel face instability in cobbles are discussed on the basis of aforementioned investigations.

scholarly journals Prediction and analysis of surface settlement due to shield tunneling for Xi’an Metro

2017 ◽  
Vol 54 (4) ◽  
pp. 529-546 ◽  
Author(s):  
Caihui Zhu ◽  
Ning Li
Keyword(s):  
Influence Factors ◽  
Estimation Method ◽  
Prediction Method ◽  
Surface Settlement ◽  
Upper And Lower Bounds ◽  
Support Pressure ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Tunneling Method ◽  
Gp Model

This study describes a new modified prediction method of surface settlement (SS) for Xi’an Metro. The estimation method of SS and its characteristic parameters, volume loss (VL), maximal SS, and settlement trough width (STW) are reviewed and discussed in this paper. The gap parameter (GP) is applied to estimate VL; however, the calculation method of GP and its influence factors have not been clarified entirely. In this study, six influence factors are introduced into the new GP model, and the detailed solutions are presented. This estimation method is able to take into account the support pressure of the shield head at the tunnel face, the lining support pressure around the tunnel opening, the filling effect of tail grouting, yawing, and pitching of the shielding machine, and the long-term deformation of the remoulded surrounding soil. Based on Xi’an Metro line 2, the soil behaviors and measured SS characteristics are deeply investigated. The upper and lower bounds of the total GP of the 15 cases are predicted. Comparison of the predicted SS troughs with field observations can show reasonable agreement. It is suggested that the new estimation method can be used effectively in estimating the SS induced by the shield tunneling method.

Study on the Stability of Large Cross-River Shield Tunnel Face with Seepage

2013 ◽  
Vol 405-408 ◽  
pp. 1371-1374 ◽  
Author(s):  
Xi Lin Lu ◽  
Feng Di Li
Keyword(s):  
Numerical Analysis ◽  
Water Level ◽  
Coupling Effect ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Seepage Force ◽  
Tunnel Face ◽  
Increasing Trend ◽  
The Stability ◽  
Shield Tunnel Face

By 3D numerical analysis, the seepage force on the tunnel face was obtained and shows linearly increasing trend with the water level. By considering the average seepage force on the wedge boundary of 3D trapezoidal wedge model, the limit support pressure to keep stability of tunnel face under seepage condition was obtained. The total limit support pressure increases almost linearly with the water level. In order to consider the deformation seepage coupling effect, the 3D coupled deformation and seepage numerical analysis was further used to investigate the influence of the water level on the failure of tunnel face, the results show the failure mode changes with the increase of water level, and the limit support pressure increases nonlinearly with the water level.

Study on the Effect of Shield Tunnel Construction on Underground Pipeline Deformation by Experiment and Monitoring

2011 ◽  
Vol 413 ◽  
pp. 289-294
Author(s):  
Li Jian Liu ◽  
Lei Yu Zhang ◽  
Jiao Xia Lan ◽  
Mei Li Wang
Keyword(s):  
Ground Surface ◽  
Deformation Monitoring ◽  
Monitoring Data ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Underground Pipeline ◽  
Gas Pipelines ◽  
Buried Pipelines ◽  
Shield Tunneling ◽  
Limit Value

The field socket gas pipeline is taken to make the loading experiment in order to study the deformation and force state of the pipelines and the limit value of the deformation curvature of the pipeline．The monitoring data from the shield tunnel construction are analyzed, the effect of shield tunneling on the deformation of ground surface and buried pipelines is studied, and the rationality of the deformation monitoring value of gas pipelines in the Shenyang area is discussed．

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