Simulation analysis of the evolution law of creep rupture crack extension in X-fractured rock body

Creep is the macroscopic manifestation of the process of generation, expansion, and penetration of microscopic cracks in a rock body. In this study, the GDEM continuous–discontinuous numerical simulation software was used to model a rock body containing X-type fissures for the purposes of exploring creep crack expansion and rupture in the rock body, analyzing the effects of various factors on X-type fissures in the rock body under the rule of change of the creep curve, and assessing the influences of the intersection angle of the fissure and other factors on the non-parallel fissure rock body on the creep rupture process. The results show that an X-type fissure rock body exhibits a mixed tensile–shear damage mode, with tensile damage being the main type of damage. In the isotropic creep stage of a rock body with X-type fissures, the steady-state creep rate initially increases and then decreases as the sub-fissure length increases, with the change of the fissure angle of the creep rate of the w-type; the sub-fissure length of h is 14mm, the rock body is the first to enter into the accelerated creep stage, for the different fissure intersection angle of the rock body For the rock mass with different fracture angles, the time sequence of entering the accelerated creep stage is consistent with the creep rate; when the fracture intersection angle is 45°, and the sub-fracture length is 12mm, the rock mass has the largest degree of fragmentation, which has a significant impact on the creep damage; after using a single variable processing, it is found that the fracture intersection angle, the sub-fracture length and other factors compared to the fracture intersection angle has a greater impact on the creep damage of the X-type fissure rock mass. This paper can provide theoretical basis and reference for the study of rock engineering creep damage law and mechanical properties of X-type rift rock body.