Computation of the Minimum Limit Support Pressure for the Shield Tunnel Face Stability Under Seepage Condition

2016 ◽  
Vol 15 (6) ◽  
pp. 849-863 ◽  
Author(s):  
Xilin Lu ◽  
Yuncai Zhou ◽  
Maosong Huang ◽  
Fengdi Li
Keyword(s):  
Shield Tunnel ◽  
Support Pressure ◽  
Tunnel Face ◽  
Face Stability ◽  
Tunnel Face Stability ◽  
Shield Tunnel Face

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.

Influence of Pipe Roof Reinforcement on Face Stability of Underwater Tunnel

2011 ◽  
Vol 261-263 ◽  
pp. 1029-1033 ◽  
Author(s):  
Kai Wang ◽  
Hai Gui Kang ◽  
Hai Tao Wang
Keyword(s):  
Support Pressure ◽  
Seepage Force ◽  
Tunnel Face ◽  
Face Stability ◽  
Seepage Pressure ◽  
Kinematic Method ◽  
The Face ◽  
Tunnel Face Stability ◽  
Underwater Tunnel ◽  
Groundwater Flow Condition

The effect of seepage force on tunnel face stability with pipe roof reinforcement was studied based on the kinematic method of limit analysis. This method can be employed to define the safety factor and its corresponding critical failure mechanism for a given tunnel. The studies revealed that the existence of groundwater may seriously affect the face stability. Under the steady-state groundwater flow condition, most part of the total support pressure is owing to the seepage pressure acting on the tunnel face. There was a relatively large reduction in the seepage pressure by adopting the pipe roof reinforcement technique.

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 Probabilistic Analysis of Tunnel Face Stability below River Using Bayesian Framework

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Weiping Liu ◽  
Xiaoyan Luo ◽  
Jinsong Huang ◽  
Lina Hu ◽  
Mingfu Fu
Keyword(s):  
Probabilistic Analysis ◽  
Three Dimensional ◽  
Friction Angle ◽  
Bayesian Framework ◽  
Computational Time ◽  
Support Pressure ◽  
Tunnel Face ◽  
Face Stability ◽  
Mcmc Simulation ◽  
Tunnel Face Stability

A key issue in assessment on tunnel face stability is a reliable evaluation of required support pressure on the tunnel face and its variations during tunnel excavation. In this paper, a Bayesian framework involving Markov Chain Monte Carlo (MCMC) simulation is implemented to estimate the uncertainties of limit support pressure. The probabilistic analysis for the three-dimensional face stability of tunnel below river is presented. The friction angle and cohesion are considered as random variables. The uncertainties of friction angle and cohesion and their effects on tunnel face stability prediction are evaluated using the Bayesian method. The three-dimensional model of tunnel face stability below river is based on the limit equilibrium theory and is adopted for the probabilistic analysis. The results show that the posterior uncertainty bounds of friction angle and cohesion are much narrower than the prior ones, implying that the reduction of uncertainty in cohesion and friction significantly reduces the uncertainty of limit support pressure. The uncertainty encompassed in strength parameters are greatly reduced by the MCMC simulation. By conducting uncertainty analysis, MCMC simulation exhibits powerful capability for improving the reliability and accuracy of computational time and calculations.

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.

Sign in / Sign up

Export Citation Format

Share Document