Analysis of mechanical behavior and acoustic emission characteristic of red sandstone with holes and cracks under uniaxial compression

In order to study the mechanical behavior and acoustic emission characteristics of rock mass with holes and cracks, the uniaxial compression numerical test of red sandstone specimens with different crack dip angles was carried out by PFC software. The fracture characteristics, stress-strain process and acoustic emission characteristics were analyzed, and the damage evolution characteristics of rock samples were initially discussed. The results show that the peak stress and elastic modulus of single fracture rock samples increase with the increase of fracture dip angle. The peak stress and elastic modulus of the three defect types of rock samples (single fracture, fracture through hole, fracture not through hole) are the smallest when the fracture dip angle is 0°, and the largest when the dip angle is 90°. The rock samples with single fracture are mostly wing cracks developed at the tip of prefabricated cracks. For rock samples with fracture not through hole, except that the crack dip angle is 90°, the instability failure modes of rock samples with other dip angles are all connected along the dip angle extension direction. The larger the fracture dip angle of single fracture rock sample is, the smaller the strain range of obvious emission is. The time when the acoustic emission signal occurs in the rock sample with fracture not through hole is earlier than that of the other two types of rock samples. The three types of rock samples (single fracture, fracture through hole, fracture not through hole) have the highest cumulative ringing count of acoustic emission when the crack dip angle is 90°.