Three-Dimensional Limit Equilibrium Solution of Minimum Support Pressure of Shield Tunnel Face in Sandy Cobble Stratum

2021 ◽  
Author(s):  
Zhang Junwei ◽  
Wan Panpan ◽  
Huang Xinmiao
Keyword(s):  
Equilibrium Solution ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Tunnel Face ◽  
Minimum Support ◽  
Shield Tunnel Face

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.

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.

scholarly journals Analysis of the Limit Support Pressure of a Shallow Shield Tunnel in Sandy Soil Considering the Influence of Seepage

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1023 ◽  
Author(s):  
Bo Mi ◽  
Yanyong Xiang
Keyword(s):  
Numerical Simulation ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Three Dimensional ◽  
Support Pressure ◽  
Tunnel Face ◽  
Dimensional Solution ◽  
Physical Model Tests

The objective was to optimize the existing solution for the limit support pressure of a tunnel face. Firstly, based on the numerical simulation results, the existing three-dimensional analytical solution for pore water pressure distribution is expanded to a three-dimensional solution considering the pore water pressure distribution in the upper formation behind the tunnel face. Then, according to the results of physical model tests, a failure model considering the failure range in the upper formation behind the tunnel face is established, and the newly established three-dimensional solution for pore water pressure is introduced into the model, and then the limit effective support pressure of the tunnel face considering seepage is obtained by the method of soil–water joint calculation. Finally, the calculation results in this paper are compared with the experimental results, numerical simulation results and existing theoretical solutions. The major findings are as follows. The distribution of pore water pressure in the front and back strata above the tunnel face is basically symmetrical. The limit effective support pressure of the tunnel face will increase linearly with an increase in the hydraulic head difference between the tunnel face and the ground surface. The calculated results of the new limit equilibrium theory are obviously larger than those of the existing theory and numerical simulation and closer to the results of the physical model tests. Therefore, the new limit equilibrium model can better predict the limit effective support pressure of the tunnel face considering seepage and provide a reference for actual projects.

scholarly journals Study on Stability of Shield Tunnel Excavation Face in Soil-Rock Composite Stratum

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Hongtao Sui ◽  
Chao Ma ◽  
Chunquan Dai ◽  
Tingzhi Yang
Keyword(s):  
Limit Equilibrium ◽  
Three Dimensional ◽  
Earth Pressure ◽  
Calculation Model ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Finite Element Software ◽  
Dimensional Finite Element ◽  
Practical Engineering ◽  
Three Dimensional Finite Element

In order to study the instability mode of shield excavation face in soil-rock composite stratum and determine the ultimate support pressure of excavation face, this paper selects two typical soil-rock composite strata and uses three-dimensional finite element software to study the failure development process of shield excavation face. Based on the principle of limit equilibrium, a calculation model of limit support pressure for soil-rock composite stratum is proposed and applied to practical engineering. It is found that the shape of “unloading loosening zone” is mainly determined by the properties of upper soil and the properties of lower rock mainly determine the scope and shape of “sliding instability zone.” With the increase of soil proportion coefficient, the ultimate bearing capacity increases nonlinearly and the growth rate decreases gradually. At the same time, the influence of overlying Earth pressure and soil cohesion cannot be ignored.

scholarly journals Three-dimensional theoretical analysis of seepage field in front of shield tunnel face

2022 ◽  
Author(s):  
Qiguang Di ◽  
Pengfei Li ◽  
Mingju Zhang ◽  
Caixia Guo ◽  
Fan Wang ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Three Dimensional ◽  
Shield Tunnel ◽  
Seepage Field ◽  
Tunnel Face ◽  
Shield Tunnel Face

scholarly journals Calculation of Limit Support Pressure for EPB Shield Tunnel Face in Water-Rich Sand

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1102 ◽  
Author(s):  
Lin Wang ◽  
Kaihang Han ◽  
Tingwei Xie ◽  
Jianjun Luo
Keyword(s):  
Numerical Simulations ◽  
Analytical Solutions ◽  
Limit Equilibrium ◽  
Hydraulic Head ◽  
Shield Tunnel ◽  
Tunnel Face ◽  
Face Stability ◽  
Distribution Rules ◽  
Approximate Analytical Solutions ◽  
Shield Tunnel Face

With the rapid development of the tunnels constructed under the rivers and seas, the research on face stability of shield tunnel in water-rich sand has important theoretical value and engineering application significance. In addition to the loads exerted by overlaying strata, the tunnels constructed in water-rich strata are usually subjected to high hydrostatic pressure or seepage forces, which are apt to cause the ground collapse of the shield tunnel face. The distribution of hydraulic head field around the tunnel face is critical to assess the impacts of the seepage forces on the tunnel face stability. This paper investigates the axisymmetric problem of the face stability of the shield tunnel under a seepage condition within the framework of limit equilibrium analysis. First, numerical simulations are carried out in this paper to analyze the distribution rules of total hydraulic head and pore water pressure near the tunnel face of the shield tunnel under the condition of stable seepage with different cover depths. Then, based on the distribution rules of total hydraulic head, new formulas for predicting the total hydraulic head along the horizontal and vertical directions are proposed and compared with the numerical simulations in this paper and existing approximate analytical solutions. Second, the classical axisymmetric limit equilibrium model is revised by incorporating the new approximate analytical solutions of hydraulic head field to determine the failure modes and the limit support pressures with a numerical optimization procedure. Lastly, the comparisons of the results obtained from the theoretical analysis model in this paper and the existing approaches are conducted, which shows that the failure mechanism proposed in this paper could provide relatively satisfactory results for the limit support pressures applied to the tunnel face.

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