Macro-meso failure study on the mechanism of central-boundary fractured rock masses
- Vol.52(2), April
- New York Springer 2022
- 301-314p.
In order to study the initiation, propagation, and failure mode of the original cracks in jointed rock masses, a uniaxial compression experiment and PFC2D numerical simulation analysis of prefabricated central-boundary fractured red sandstone specimens were performed, and the influence mechanism and mechanical behavior of the central fractures of different angles on the crack propagation of boundary fractured rock masses were obtained. The results show that the central fracture will change the crack initiation sequence and failure mode of the boundary fractured rock mass. The initial cracks begin from the central fracture, and the key cracks that dominate the instability of the specimen occur at the initial crack initiation position. The failure of the upper and lower rock bridges is the main reason for the failure of the central-boundary fractured rock mass specimen. As the angle of the central fracture increases, the area of scratch surface in the macroscopic failure section of the specimen increases first and then decreases, the failure process types of the specimen are tensile-shear failure, shear failure, and shear-tension failure. Under the condition of different central fracture inclination angles β, the initial crack stress, peak stress, and total number of cracks show an overall increasing trend as the central fracture angle increases in the numerical simulation. The minimum value of the initial crack stress and the peak stress is approximately 0°, and the maximum value of the peak stress occurs when the crack angle is 90°. The number of shear cracks does not change significantly.