Numerical simulation of cumulative damage and seismic energy release during brittle rock failure - Part I: Fundamentals

This paper presents a numerical approach for the simulation of damage initiation and propagation causing seismic energy release during unstable failure of brittle rock. With a newly developed numerical code, RFPA(2D) (Rock Failure Process Analysis), the progressive failure process leading to the development of a shear or fault zone, and the eventual collapse of a heterogeneous rock sample is modeled. Since the constitutive law for each element in the model is elastic-brittle, seismic-brittle, seismic energy is radiated whenever an element fails. It is assumed that the radiated energy is equal to the energy stored in the element before failure is triggered. Due to the heterogeneity of rock properties, seismic quiescence may occasionally occur within the nucleation zone. The cumulative seismic damage calculated based on the seismic event rate from the simulation can be used as a damage parameter to describe the damage evolution. It was found that significant decreases followed by sudden increases in radiated seismic energy may be an indicator of potentially unstable nucleation. (C) 1998. Published by Elsevier Science Ltd.