Microscopic Numerical Simulation Of Deformation And Failure Process Of Rock Under True Triaxial Stress

At present,the study of rock deformation and failure process is based on the conventional three axis stress state,but in the true three axis stress environment,the deformation and failure characteristics of underground engineering rock mass are different from the conventional three axis stress environment.Therefore,the study of the deformation and failure process of rock under the true three axis stress condition is of great theoretical significance and guiding value for revealing the mechanism of rock failure in underground engineering.In this paper,numerical simulation and laboratory test are combined to study the deformation and failure process of rock under the true three axis stress state.The main results are as follows:(1)The particle flow discrete element program PFC3 D is used to establish the true three axis numerical model of rock.The sensitivity of meso parameters is analyzed,and a set of micro parameters conforming to laboratory tests are obtained.(2)Based on the established true three axis numerical model of rock,this paper studied the three axle stress state and deformation characteristics,rock strength characteristics,damage and damage characteristics,and discussed the failure process of rock deformation and intermediate principal stress effect,which reveals the mechanism of intermediate principal stress on rock deformation and failure with a kind of trend of "first restrain and then rise".The simulation of rock deformation and failure under the real three axis stress state shows that the macro fracture mainly occurs on the vertical plane of the intermediate principal stress direction,but there is no macro fracture in the vertical direction of the minimum principal stress.(3)Firstly,the rock strength theory is used to analyze the rock strength characteristics.It is shown that the Mogi-Coulomb strength criterion can better describe the rock strength characteristics under the true three axis stress state.Secondly,the characteristics of rock deformation and failure are also studied by using the crack strain theory,and the effect of intermediate principal stress on rock failure evolution mechanism is further verified.Finally,the damage variables are defined based on the bond failure characteristics,and the rock damage constitutive model under the three real stress state is established by using the rock damage theory to reveal the mechanism of rock damage,failure and evolution.