Stress initialization methods for dynamic numerical simulation of rock mass with high in-situ stress

In the context of deep rock engineering, the in-situ stress state is of major importance as it plays an important role in rock dynamic response behavior. Thus, stress initialization becomes crucial and is the first step for the dynamic response simulation of rock mass in a high in-situ stress field. In this paper, stress initialization methods, including their principles and operating procedures for reproducing steady in-situ stress state in LS-DYNA, are first introduced. Then the most popular four methods, i.e., explicit dynamic relaxation (DR) method, implicit-explicit sequence method, Dynain file method and quasi-static method, are exemplified through a case analysis by using the RHT and plastic hardening rock material models to simulate rock blasting under in-situ stress condition. Based on the simulations, it is concluded that the stress initialization results obtained by implicit-explicit sequence method and dynain file method are closely related to the rock material model, and the explicit DR method has an obvious advantage in solution time when compared to other methods. Besides that, it is recommended to adopt two separate analyses for the whole numerical simulation of rock mass under the combined action of in-situ stress and dynamic disturbance.