Numerical investigation of the face stability of shallow tunnels in sand

2010 ◽  
pp. 795-800
Keyword(s):  
Numerical Investigation ◽  
Face Stability ◽  
Shallow Tunnels ◽  
The Face

Failure modes and face instability of shallow tunnels under soft grounds

2018 ◽  
Vol 28 (4) ◽  
pp. 566-589 ◽  
Author(s):  
Zhiqiang Zhang ◽  
Huayun Li ◽  
Hongyu Yang ◽  
Bo Wang
Keyword(s):  
Failure Modes ◽  
Pressure Coefficient ◽  
Soil Formation ◽  
Sandy Soils ◽  
Theoretical Models ◽  
Upper Bound Theorem ◽  
Tunnel Face ◽  
Face Stability ◽  
Shallow Tunnels ◽  
The Face

For shallow tunnels under soft grounds, it is very difficult to gain a complete understanding on all the load-bearing arch effects during excavation, since such tunnels can easily deform or even collapse. Among these effects, the tunnel face stability plays the most important role and has not been understood and handled very well; therefore, the design and construction of such tunnels under soft grounds remain as a challenge. In this work, the different failure models of face instability of the shallow tunnels were established based on the upper-bound theorem of limit analysis for the formation of clayey and sandy soils, respectively, and the analytical equations for determining the limit support force for the face stability were also derived. Furthermore, the influences of various factors on the stability were analyzed and compared. For the sandy soil formation, an equivalent pressure coefficient was proposed for the tunnel faces of bolt reinforcement. Finally, taking the face stability of the shallow tunnels in sandy soils as an example, a complete numerical simulation was conducted to verify the accuracy and effectiveness of the analytical results based on the theoretical models as well as their application conditions.

Three-dimensional face stability analysis of shallow tunnels using numerical limit analysis and material point method

2021 ◽  
Vol 112 ◽  
pp. 103904
Author(s):  
Fabricio Fernández ◽  
Jhonatan E.G. Rojas ◽  
Eurípedes A. Vargas ◽  
Raquel Q. Velloso ◽  
Daniel Dias
Keyword(s):  
Stability Analysis ◽  
Limit Analysis ◽  
Three Dimensional ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Face Stability ◽  
Shallow Tunnels ◽  
Dimensional Face

DEM and theoretical analyses of the face stability of shallow shield cross-river tunnels in silty fine sand

2021 ◽  
Vol 130 ◽  
pp. 103905
Author(s):  
Zhihua Zhang ◽  
Wensheng Xu ◽  
Wenting Nie ◽  
Lingmin Deng
Keyword(s):  
Fine Sand ◽  
Face Stability ◽  
Cross River ◽  
The Face ◽  
Theoretical Analyses

Risk Analysis and Assessment for the Face Stability of Tunnel

2011 ◽  
Vol 261-263 ◽  
pp. 380-384
Author(s):  
Hai Tao Wang ◽  
Jin Qing Jia
Keyword(s):  
Numerical Simulation ◽  
Monte Carlo Simulation ◽  
Probability Of Failure ◽  
Stability Factor ◽  
Critical Element ◽  
Face Stability ◽  
Starting Point ◽  
The Face ◽  
Design Value ◽  
Acceptable Probability

The evaluation of the correct stability factor of tunnel is a critical element in the various design and construction phases of a tunnel excavated in difficult geotechnical conditions. An innovative, and well-applied, procedure for optimize the construction phase management is described in this article. The starting point of this procedure involves the verification of the results of numerical methods obtained from referenced analytical methods. In the first step of the procedure the results obtained through the analytical method are verified by means of a numerical method in order to evaluate the practical consequences in terms of development of deformations and plastic zone. In this manner, the assumed design risk is evaluated for the different methods and the solution that gives the best correspondence with numerical simulation is selected. Finally, residual uncertainties and parametric variations are incorporated in the analysis and Monte Carlo simulation is used to calculate the statistical distribution of the face-stabilizing pressure and the design value is selected on the basis of an acceptable probability of failure.

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