DEM investigation on the mechanical behaviors of flawed specimens subjected to coupled static-dynamic loads

Abstract

Underground rock masses containing preexisting flaws are usually subjected to a coupled effect of static pre-stress and dynamic disturbance involving earthquake. Understanding the effects of seismic strain rates on the mechanical behaviors of flawed rocks subjected to static pre-stresses is significant for assessing the stability and safety of underground projects. In this study, the mechanical properties and the cracking behaviors of rock specimens with both parallel and unparallel flaws under different coupled static-dynamic loads are numerically investigated. The numerical results showed the effects of seismic dynamic strain rate on the mechanical parameters of flawed specimens subjected to different static pre-stresses. All the flawed specimens under seismic strain rates are characterized by higher coupled strength and elastic modulus. The highest coupled strength and elastic modulus of flawed specimens occurs under the static pre-stress of half uniaxial compression strength. The seismic strain rate induces a more sensitive evolution of input energy and strain energy than those under individual static loading. Furthermore, the crack evolution mechanisms of the numerical specimens with both parallel and unparallel flaws are comprehensively revealed.