Deformation,Failure And Crack Propagation Test And Numerical Simulation Of Layered Rock Mass

The layered rock mass is widely existed in nature and usually has obvious anisotropic characteristics.Most of the dominant layers belong to the material differentiation surface.The mechanical differences between the rock layers will cause various macroscopic and microscopic fractures and joints.These initial damages make the rock mass deformation process more complicated.The study of layered rock mass should focus on the mechanical relationship between deformation and anisotropy between layers,and establish the relationship between the geometric and mechanical properties of the structural plane.In addition,for multi-joined layered rock masses such as slopes or chambers,in addition to considering the effects of the layers,the effects of cracks,joints,etc.on deformation and strength characteristics should be analyzed.Therefore,combined with laboratory experiments,theoretical analysis and numerical simulation methods,the failure characteristics and strength characteristics of layered rock mass are studied,and the influence of fracture on the mechanical properties of layered rock mass and the deformation mechanism of layered rock mass slope are further analyzed.The specific research contents and main research results are as follows:(1)The conventional uniaxial and triaxial compression test were carried out on layered composite rock samples with different bedding angles.The characteristics of stress-curves,deformation and failure modes under different bedding angles and confining pressures are compared and analyzed.Based on the nonlinear failure criterion,the strengths of the two failure modes,slip and non-slip,are theoretically analyzed.The calculated peak strength under different confining pressures is in good agreement with the indoor test data.(2)The conventional uniaxial test of prefabricated layered composite rock samples was carried out.The stress characteristics,strength characteristics and failure modes of different fracture dip angles and bedding angles were analyzed.The basic types of crack initiation,propagation and penetration failure were summarized.The deformation and strength characteristics of the layered composite rock mass with or without cracks are compared.The influence of the existence of prefabricated cracks on the strength and deformation of the layered rock mass under different bedding angles is discussed.(3)Based on the discrete element PFC2 D,the macroscopic intensity calibration of the macroscopic parameters was carried out.The numerical simulation analysis of the layered and cracked layered indoor single and triaxial tests was carried out.The macroscopic strength and model failure modes of the numerical and experimental models were compared and analyzed.The evolution process of microcracks and meso-force chains in the model with macroscopic mechanical strength.(4)Based on the characteristics of the structural planes in the layered rock mass slope,the numerical model of the generalized layered slope is calculated by the heavy increase method.The crack propagation pattern and the displacement field characteristics are used to analyze the slopes of different bedding angles and slopes under the slope angle.The deformation mechanism is taken as an example.The evolution process of slope stress and microcrack length with slope deformation is analyzed.The failure mechanism and influence law of cracked layered slope under the influence of weak weathering are discussed.