Fracture Process And Damage Evolution Characteristics Of Three-dimensional Irregular Rocks With Crack

Under the influence of external force,cracks in the rock of Jinfeng gold mine are easy to lead to rock mass instability and even engineering collapse.Therefore,it is of great significance to explore the damage and failure characteristics of 3D irregular rock with fractures for predicting and controlling the structural stability of fractured rock mass.the sandstone in the wall rock of the roadway in the middle150 section of Jinfeng gold mine is taken as the research object,Uniaxial compression tests are carried out on the similar simulated specimens with cracks under different loading conditions.The RFPA^3Dnumerical model of sandstone with different fracture dip angles and geometric parameters was established to analyze irregular sandstone with fractures based on multidimensional fractal and acoustic emission damage theory.The main research results are as follows:（1）It was found that the maximum average compressive strength of multi-contact specimens was1.683 MPa,and the minimum average compressive strength of point-to-point specimens was 1.163MPa.The airfoil crack propagation is the main fracture path of the specimen,but the airfoil crack propagation path of the specimen under different loads is deflecting to the high stress region.（2）the uniaxial compressive strength of sandstone specimens decreases first and then increases with the increase of fracture dip Angle under the same loading conditions.When the fracture dip Angle is 45°,the peak strength of specimens reaches the minimum value.（3）The influence of fracture geometry parameters on sandstone failure is in the order of depth>length>opening.Compared with regular specimens,the depth of point-to-point specimens has a greater influence on the strength of the specimens.（4）A multi-dimensional fractal dimension calculation program was developed based on Matlab.It was found that the fractal dimension of the specimen increased with the increase of the damage degree of rock and rock.Through the damage analysis of sandstone specimens by the modified AE formula,it is found that the damage threshold of sandstone with different fracture inclination angles is between0.2 and 0.4 when it enters the plastic stage.