| Surrounding layered rock mass has attracted intensive research interest due to their importance in tunneling engineering. As the failure mechanism and the failure mode of layered rock mass are significantly different from other rock, built in such rock, tunnel rock deformation and the form of destruction are relatively complicated. It makes demands of stabilization of surrounding layered rock mass.In allusion to the characteristics of layered rock, on the background of GL2 tunnel project, this paper analyzed the stability of surrounding rock using DEM(discrete element method).On the basis of monitoring data of GL2 tunnel project, an improved method for evaluation the stability of surrounding layered rock mass of tunnels is proposed. Without considering cross-coupling effects of the influencing factors, the criteria for the stability of surrounding layered rock mass of tunnels have been applied in our analysis. The stability of surrounding layered rock mass is studied systematically in this paper. Contents and resulting achievements of this paper are as follows:Firstly, a criterion for the stability of surrounding layered rock mass of tunnels is proposed. In our method for evaluation the stability of surrounding layered rock mass of tunnels, the displacement of cavity, the plastic zone in surrounding layered rock mass and the shear slip zone are the influencing factors. Comparing with numerical simulation, these three influencing factors are essential and effective.Secondly, we analyzed influence of the layered rock mass properties for the stability of surrounding layered rock mass of tunnels. In our numerical simulation, the slope of layered rock mass, the thickness of layered rock mass, the strength of layered rock mass, its burial depth and the coefficient of lateral pressure are considered. The simulation results shows influence of the layered rock mass properties for the stability of surrounding layered rock mass of tunnels.Finally, by considering the layered rock mass properties and the occurrence condition, we analyzed the stability of surrounding layered rock mass of tunnels. The significant degree of layered rock mass properties and the occurrence condition in the stability of surrounding layered rock mass of tunnels are determined with the orthogonal experimental method. Moreover, the significant degree of the mechanics properties of layered rock mass, its cohesive strength and its internal friction angle, are determined with the double factors for non-repetition experiments... |
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