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Geomechanics and Engineering
  Volume 24, Number 5, March10 2021 , pages 491-503
DOI: https://doi.org/10.12989/gae.2021.24.5.491
 


Limit analysis of seismic collapse for shallow tunnel in inhomogeneous ground
Zihong Guo, Xinrong Liu and Zhanyuan Zhu

 
Abstract
    Shallow tunnels are vulnerable to earthquakes, and shallow ground is usually inhomogeneous. Based on the limit equilibrium method and variational principle, a solution for the seismic collapse mechanism of shallow tunnel in inhomogeneous ground is presented. And the finite difference method is employed to compare with the analytical solution. It shows that the analytical results are conservative when the horizontal and vertical stresses equal the static earth pressure and zero at vault section, respectively. The safety factor of shallow tunnel changes greatly during an earthquake. Hence, the cyclic loading characteristics should be considered to evaluate tunnel stability. And the curve sliding surface agrees with the numerical simulation and previous studies. To save time and ensure accuracy, the curve sliding surface with 2 undetermined constants is a good choice to analyze shallow tunnel stability. Parameter analysis demonstrates that the horizontal semiaxis, acceleration, ground cohesion and homogeneity affect tunnel stability greatly, and the horizontal semiaxis, vertical semiaxis, tunnel depth and ground homogeneity have obvious influence on tunnel sliding surface. It concludes that the most applicable approaches to enhance tunnel stability are reducing the horizontal semiaxis, strengthening cohesion and setting the tunnel into good ground.
 
Key Words
    shallow tunnel; seismic collapse; inhomogeneous ground; limit analysis; variational principle
 
Address
Zihong Guo and Zhanyuan Zhu: 1.) College of Civil Engineering, Sichuan Agricultural University, Dujiangyan, Sichuan, 611830, China
2.) Sichuan Higher Institution Engineering Research Center of Rural Construction Disaster Prevention and Reduction, Dujiangyan, 611830, China

Xinrong Liu: School of Civil Engineering, Chongqing University, Chongqing 400045, China
 

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