Numerical simulation of supershear ruptures in rock mass based on general particle dynamics

Abstract

AbstractIn this paper, general particle dynamics code is developed to simulate initiation and growth of earthquake ruptures in rocks subjected to spontaneous dynamic unloading as well as the elastic stress distributions. The Mohr‐Coulomb criterion is applied to determine initiation and propagation of dynamic cracks. The effects of factors on the threshold of earthquake rupture from the slow, sub‐Rayleigh to supershear mode are investigated. The thresholds of the slow, sub‐Rayleigh and supershear mode are determined as well as the rupture velocity on the fault trace. It is found from the numerical results that the supershear rupture occurs when the ratio of shear stress to the normal stress acting on the surface of fault is larger than the critical threshold value; the supershear rupture also appears when friction coefficient, the stress drop ratio, confining pressure, and residual strength are less than the critical threshold value. The near‐field signatures in the both of ground velocity and stress records are determined. Moreover, both velocity wave and stress wave in the near field of supershear Mach fronts in the plane are analysed using general particle dynamics code.