Investigations on the macro‐meso mechanical properties and energy dissipation mechanism of granite shear fracture under dynamic disturbance

Abstract

AbstractTo explore the mechanical characteristics and failure mechanisms of rock shear fracture under dynamic disturbance, the laboratory shear test and numerical simulation based on particle flow code (PFC) were carried out, and the mesoscopic degradation characteristics and energy dissipation mechanisms of rock shear fracture were analyzed. The results show that: (1) The crack initiation stress of rock under the disturbance condition is relatively reduced by 20%–29%, and there is a “shear fracture weakening effect.” The frequent alternating effect of stress concentration and release at the post‐peak failure stage is more obvious. (2) The number of cracks in rock under shear action shows the evolution of “calm → low speed growth → rapid increase → decrease of amplification → stabilization” with the increase of shear displacement. Compared with the conventional shear test, more cracks, and wider debris zones are formed. The number of cracks increases by 53%–106%, and the number of debris increases by 31%–138%. (3) The energy change trend of disturbance shear fracture test is basically consistent with that of conventional shear test. With the increase of normal stress, the input energy, elastic strain energy and dissipation energy of rock failure point show a certain linear growth feature. Compared with the conventional shear test, the input energy and stored strain energy of the failure point in the disturbance shear test are smaller, with relative reduction of 16.5% and 22.1%. Namely, the normal frequent disturbance reduces the energy storage capacity and failure resistance of rock.