Analysis of deformation characteristics of a tunnel in layered soft rocks with considering the effect of bedding

Abstract

Abstract The layered soft rock tunnel is affected by the combination of layering and geostress, and it is easy to cause large deformation disaster. Based on the Weiwu high-speed Minxian tunnel, the influence of bedding on the stress and deformation characteristics of sandstone and carbon slate is studied in this paper. The calculation results show that the influence of bedding on the deformation of sandstone and carbonaceous slate is significant. If the influence of bedding is not considered in the process of tunnel deformation prediction, the deformation of surrounding rock will be seriously underestimated. The influence of bedding on the deformation distribution of surrounding rock is related to the strength of bedrock. For sandstone, the strength of bedrock is high, and the deformation and failure of surrounding rock is mainly caused by shear failure of layer, and its deformation distribution and magnitude It is obviously affected by the layered production. When the angle between the bedding and the maximum principal stress direction of the ground stress is 45°, the deformation amount reaches the maximum value. For the layered carbonaceous slate, due to the low strength of the bedrock, the surrounding rock has obvious crushing damage zone after the tunnel excavation, and the layered occurrence has little influence on the deformation value and distribution of the surrounding rock. The maximum deformation orientation of the surrounding rock is basically perpendicular to the direction of the maximum principal stress of the geostress.