Effect Of Anisotropy On Mechanical Response Of Surrounding Rocks Of Large Cavern In Steep-dip Layered Rock Mass

Aiming at the anisotropic effect of the mechanical response of the surrounding rock of the cavern when the angle between the axial direction of the cavern and the strike of the rock strata changes in the steep-dip layered rock mass with significant mechanical anisotropy,this paper takes the dynamic evolution of the surrounding rock as the basic idea,based on the related principles and theories of mechanics,geomechanics and rock mass mechanics,using on-site investigations,indoor and outdoor tests,theoretical analysis and numerical calculations,etc.,to study the mechanical response,including surrounding rock stress,surrounding rock deformation and failure,of large underground caverns in steep-dip layered rock masses under excavation conditions.The main results of the thesis are as follows.（1）Under the comprehensive influence of the anisotropy of the natural in-situ stress field,the anisotropy of rock mechanical properties and the anisotropy of the rock mass structure,the mechanical properties of the natural rock mass in the study area have significant anisotropy characteristics.（2）Under the excavation conditions of the natural rock mass in the study area,the mechanical response of the surrounding rock of the cavern（including the stress of the surrounding rock after redistribution,the deformation and the failure of the surrounding rock）has anisotropic effect with the change of the angle between the axial direction of the cavern and the strike of the rock strata.The anisotropy effect is manifested as the greater the angle between the cavern’s axial direction and the strata strike,the degree of stress release caused by the excavation of the surrounding rock will gradually decrease,the deformation of the surrounding rock will gradually weaken,and the damage range of the surrounding rock will become smaller and smaller.（3）The anisotropy of the mechanical response of the steep-dip layered surrounding rock of a large cavern under excavation conditions also has spatial effects,including the end restraint effect,the depth effect of the surrounding rock,and the difference effect around the cavern.The end restraint effect shows that under the same other influencing factors,the farther away from the end wall,the more significant the anisotropic effect of mechanical response of surrounding rock is.Surrounding rock depth effect means that when other influencing factors are the same,the farther away from the cave wall,the anisotropy of mechanical response of surrounding rock gradually weakens until it returns to the natural state.The difference effect around the cavern is mainly manifested in that the anisotropy of the mechanical response of different parts within the same cross-section is significantly different.For example,the change of the angle between the cavern’s axial direction and the strata strike has a stronger influence on the anisotropy effect of the mechanical response of the side walls than on the top arch and the bottom plate.