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Geomechanics and Engineering
  Volume 11, Number 6, December 2016 , pages 867-877
DOI: https://doi.org/10.12989/gae.2016.11.6.853
 


Roof collapse of shallow tunnel in layered Hoek-Brown rock media
X.L. Yang and K.F. Li

 
Abstract
    Collapse shape of tunnel roof in layered Hoek-Brown rock media is investigated within the framework of upper bound theorem. The traditional collapse mechanism for homogeneous stratum is no longer suitable for the present analysis of roof stability, and it would be necessary to propose a curve failure mode to describe the velocity discontinuity surface in layered media. What is discussed in the paper is that the failure mechanism of tunnel roofs, consisting of two different functions, is proposed for layered rock media. Then it is employed to investigate the impending roof failure. Based on the nonlinear Hoek-Brown failure criterion, the collapse volume of roof blocks are derived with the upper bound theorem and variational principle. Numerical calculations and parametric analysis are carried out to illustrate the effects of different parameters on the shape of failure mechanism, which is of overriding significance to the stability analysis of tunnel roof in layered rock media.
 
Key Words
    layered rock; nonlinear failure criterion; tunnel roof
 
Address
School of Civil Engineering, Central South University, Hunan 410075, China.
 

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