Analysis of fracture evolution characteristics of coplanar double fracture rock under uniaxial compression

In order to study the influence of fracture on the failure characteristics of rhyolite, the particle flow software (PFC2D) was used to simulate the uniaxial compression experiments of rhyolite with two coplanar fractures. The effects of fracture inclination angle, fracture length, length of rock bridge and fracture width on failure characteristics of the fractured rock were analyzed. It was shown that with the increase of the fracture inclination angle, the length of the fracture and the width of the fracture, the ultimate failure mode of the fractured rock changed from macroscopic shear failure to macroscopic tension–shear composite failure. With the increase of the length of the rock bridge, the ultimate failure mode of the fractured rock changed from macroscopic tension–shear composite failure to the macroscopic shear failure. The peak strength of the fractured rock varied nonlinearly with the increase of the fracture inclination angle. It tended to decrease monotonously with the increase of the fracture length. With the increase of the length of the rock bridge, it increased first, then decreased and increased finally. It decreased monotonously with the increase of the width of the fracture.