scholarly journals A Displacement-Based Theory for Predicting the Support Force on the Shield Tunneling Surface in Sandy Soil Layers

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Guang Sun ◽  
Han Liu ◽  
Zhiyuan Guo ◽  
Ranjie Li ◽  
Tao Li
Keyword(s):  
Numerical Simulation ◽  
Sandy Soil ◽  
Soil Layer ◽  
Three Dimensional ◽  
Earth Pressure ◽  
Shield Tunnel ◽  
Soil Pressure ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Support Force

Due to the poor stability of the loose sandy soil layer, if the support force is not properly controlled during the construction process of the shield tunnel using the earth pressure balance method, it is easy to cause the ground to collapse or uplift. Therefore, understanding the support force of the excavation surface of shield tunneling in sandy soil layer is very vital to ensure the stability of the excavation surface. Firstly, it is assumed that the damaged soil is a three-dimensional wedge and a modified three-dimensional wedge in the active and passive failure modes, respectively. The shallow soil pressure theory and the soil plastic limit equilibrium theory are derived by analyzing the stress distribution on the damaged soil. The equation for revealing the inner essence between the support force of the shield excavation surface and excavation surface displacement under the condition of sand-covered soil is used. Secondly, the numerical simulation method analyzes the displacement of the excavation surface when the support force changes under different working conditions, and the relationship curve between the excavation surface support force and the shield tunneling displacement is obtained. The comparison and analysis between the numerical simulation calculation and the theoretical analysis indicate that the deduced calculation equation for the excavation surface support force based on the displacement earth pressure is reasonable.

Research on Chamber Earth Pressure of EPB Shield Considering Soil Arching Effect

2014 ◽  
Vol 1065-1069 ◽  
pp. 373-377
Author(s):  
Jing Cao ◽  
Hai Xing Yang ◽  
Bo Liang ◽  
Hai Ming Liu
Keyword(s):  
Earth Pressure ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Soil Arching ◽  
Shield Tunneling ◽  
Arching Effect ◽  
Soil Arching Effect ◽  
Earth Pressure Balance ◽  
Tunnel Depth ◽  
Epb Shield

Chamber earth pressure is one of the significant parameters during the Earth Pressure Balance (EPB) shield construction processing. The soil arching effect is existence when the tunnel depth is enough. It is significant to consider the influence of arching effect to analyze the pressure in soil chamber in shield tunneling. In this paper, the influence of arching effect is considered to calculate the chamber earth pressure. Firstly, the soil is supposed as loose media, and the necessary buried depth of producing arching affects is deduced according to the loose media theory. Then, based on the characteristic of proper arching axis, the equation and the height of proper arch are obtained. At last, the calculation formula of minimum chamber earth pressure of EPB shield tunnel is deduced which can consider the effect of arching effect.

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.

scholarly journals Numerical Simulation of EPB Shield Tunnelling with TBM Operational Condition Control Using Coupled DEM–FDM

2021 ◽  
Vol 11 (6) ◽  
pp. 2551
Author(s):  
Hyobum Lee ◽  
Hangseok Choi ◽  
Soon-Wook Choi ◽  
Soo-Ho Chang ◽  
Tae-Ho Kang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Tunnel Boring Machine ◽  
Chamber Pressure ◽  
Screw Conveyor ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Operational Conditions ◽  
Shield Tunnelling ◽  
Epb Shield

This study demonstrates a three-dimensional numerical simulation of earth pressure balance (EPB) shield tunnelling using a coupled discrete element method (DEM) and a finite difference method (FDM). The analysis adopted the actual size of a spoke-type EPB shield tunnel boring machine (TBM) consisting of a cutter head with cutting tools, working chamber, screw conveyor, and shield. For the coupled model to reproduce the in situ ground condition, the ground formation was generated partially using the DEM (for the limited domain influenced by excavation), with the rest of the domain being composed of FDM grids. In the DEM domain, contact parameters of particles were calibrated via a series of large-scale triaxial test analyses. The model simulated tunnelling as the TBM operational conditions were controlled. The penetration rate and the rotational speed of the screw conveyor were automatically adjusted as the TBM advanced to prevent the generation of excessive or insufficient torque, thrust force, or chamber pressure. Accordingly, these parameters were maintained consistently around their set operational ranges during excavation. The simulation results show that the proposed numerical model based on DEM–FDM coupling could reasonably simulate EPB driving while considering the TBM operational conditions.

Analysis of Soil Disturbance by Shield Tunneling

2013 ◽  
Vol 734-737 ◽  
pp. 502-506
Author(s):  
Meng Lin Xu ◽  
De Shen Zhao
Keyword(s):  
Numerical Simulation ◽  
Soil Disturbance ◽  
Technical Support ◽  
Surface Subsidence ◽  
Stress Redistribution ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Soil Deformation ◽  
Shield Tunneling ◽  
Induced Stress

The shield tunneling will be bound to disturb surrounding strata, induced stress redistribution in soil, soil deformation and surface subsidence. We analyzed characteristics of soil disturbance by shield tunneling with numerical simulation. To provide technical support for the future urban shield tunnel construction. It shows practically significant in studying shield tunnel construction.

Numerical Simulation on the Surface Subsidence Effect during Shield Tunneling Construction

2011 ◽  
Vol 299-300 ◽  
pp. 110-113
Author(s):  
Hai Xia Sun ◽  
Hai Yu Wu ◽  
Si Li Chen
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Surface Deformation ◽  
Influence Factors ◽  
Surface Subsidence ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Finite Element Program ◽  
Element Program ◽  
Numerical Simulation Methods

Against the background of shenyang subway shield tunnel construction, the method of numerical simulation methods are used to analyze the factors of surface subsidence caused by shield construction comprehensively, and the universal finite element program ABAQUS is used to establish mechanical model depended on comprehensive consideration the influence factors of soil warehouses pressure, seepage and groundwater. A dynamic finite element simulation of shield advance process and conclude the surface deformation rule of soil are studied.

Three-Dimensional Face Stability Analysis of EPBS Tunnels

2011 ◽  
Vol 378-379 ◽  
pp. 449-452
Author(s):  
Xue Gang Huang ◽  
Yu You Yang ◽  
Gui He Wang
Keyword(s):  
Three Dimensional ◽  
Earth Pressure ◽  
Pressure Balance ◽  
Circular Tunnel ◽  
Face Stability ◽  
Analysis Theory ◽  
The Face ◽  
Earth Pressure Balance Shield ◽  
Earth Pressure Balance ◽  
Kinematical Approach

A three-dimensional (3D) failure mechanism, based on the framework of the kinematical approach of limit analysis theory, is applied to calculate the face supporting pressure of a circular tunnel driven by the Earth Pressure Balance Shield (EPBS). The geometry of the mechanisms considered is composed of a sequence of truncated rigid cones. The numerical results obtained are presented.

scholarly journals 3D MODELLING OF TUNNEL EXCAVATION USING PRESSURIZED TUNNEL BORING MACHINE IN OVERCONSOLIDATED SOILS

2013 ◽  
Vol 35 (2) ◽  
pp. 3-17 ◽  
Author(s):  
Rafik Demagh ◽  
Fabrice Emeriault
Keyword(s):  
Numerical Simulation ◽  
Urban Areas ◽  
Three Dimensional ◽  
Ground Surface ◽  
Tunnel Boring Machine ◽  
Confining Pressure ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Tunnel Boring ◽  
Boring Machines

Abstract The construction of shallow tunnels in urban areas requires a prior assessment of their effects on the existing structures. In the case of shield tunnel boring machines (TBM), the various construction stages carried out constitute a highly three-dimensional problem of soil/structure interaction and are not easy to represent in a complete numerical simulation. Consequently, the tunnelling- induced soil movements are quite difficult to evaluate. A 3D simulation procedure, using a finite differences code, namely FLAC3D, taking into account, in an explicit manner, the main sources of movements in the soil mass is proposed in this paper. It is illustrated by the particular case of Toulouse Subway Line B for which experimental data are available and where the soil is saturated and highly overconsolidated. A comparison made between the numerical simulation results and the insitu measurements shows that the 3D procedure of simulation proposed is relevant, in particular regarding the adopted representation of the different operations performed by the tunnel boring machine (excavation, confining pressure, shield advancement, installation of the tunnel lining, grouting of the annular void, etc). Furthermore, a parametric study enabled a better understanding of the singular behaviour origin observed on the ground surface and within the solid soil mass, till now not mentioned in the literature.

Numerical Simulation of Shield Tunnel Passing Through Underground Structure

2011 ◽  
Vol 105-107 ◽  
pp. 886-891
Author(s):  
Yong Suo Li ◽  
Ke Neng Zhang ◽  
Mei Long Deng ◽  
Chang Bo Huang
Keyword(s):  
Numerical Simulation ◽  
Underground Structure ◽  
Frame Structure ◽  
Shield Tunnel ◽  
Engineering Practice ◽  
Underground Engineering ◽  
Shield Tunneling ◽  
Tunnel Excavation ◽  
Mine Excavation ◽  
End Wall

Shield tunneling is often adopted in underground engineering such as civil tunnel construction and mine excavation. The program FLAC3D is used to simulate the process of the tunnel excavation through underground structure in Shenyang in this paper. The analysis results show that,(1) the soil below the end wall suffers great displacement, when the shield approaches the end wall of underground framework from different directions, so the soil under the end wall needs to be reinforced. (2) Increasing pressure and volume of grouting can’t significantly reduce the amount of surface subsidence when the drilling of the shield acrosses through the independent foundation. (3) The influences of shielding to the construction are limited because of the constraint function to the surrounding rock above the tunnel by the great entire rigidity of under-ground framework. The results of numerical simulation exactly matches the monitoring data when the stiffness of under-ground frame structure is considered, and it can provide guidance for engineering practice.

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