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Effect of surface bolt on the collapse mechanism of a shallow rectangular cavity

  • Huang, Fu (School of Civil Engineering, Changsha University of Science and Technology) ;
  • Zhao, Lian-heng (School of Civil Engineering, Central South University) ;
  • Zhang, Sheng (School of Civil Engineering, Hunan City University)
  • Received : 2014.10.16
  • Accepted : 2017.04.05
  • Published : 2017.09.25

Abstract

Based on the collapse characteristics of a shallow rectangular cavity, a three-dimensional failure mechanism which can be used to study the collapsing region of the rock mass above a shallow cavity roof is constructed. Considering the effects of surcharge pressure and surface bolt on the collapsing block, the external rate of works produced by surcharge pressure and surface bolt are included in the energy dissipation calculation. Using variational approach, an analytic expression of surface equation for the collapsing block, which can be used to study the collapsing region of the rock mass above a shallow cavity roof, is derived in the framework of upper bound theorem. Based on the analytic expression of surface equation, the shape of the collapsing block for shallow cavity is drawn. Moreover, the changing law of the collapsing region for different parameters indicates that the collapsing region of rock mass decreases with the increase of the density of surface bolt. This conclusion can provide reference for practicing geotechnical engineers to achieve an optimal design of supporting structure for a shallow cavity.

Keywords

Acknowledgement

Supported by : National Natural Science Foundation, Changsha University of Science and Technology

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