Wave and fracture propagation in continuum and faulted rock masses: distinct element modeling

Abstract

In this study, to investigate the dynamic fracture mechanism of blast-induced fracturing of rock mass around a blasthoe, two-dimensional (2D) distinct element method was used. The dynamic stresses, material status, and velocity vectors are shown to investigate rock mass failure subjected to blast load. On the other hand, rock masses consist of intact rock and discontinuities such as faults, joints, and bedding planes. The presence of such discontinuities in rock masses dominates the response of jointed rock masses to static and dynamic loading. This paper focuses on the effect of fault orientation on dynamic fracturing of rock mass. In order to investigate the effect of faults on dynamic fracturing of rock mass, a numerical simulation was conducted. The two-dimensional (2D) distinct element code was used to simulate the effect of a fault on rock failure and stress distribution through the rock mass due to blast wave propagation. The blast loading history was calculated using analytical method and was applied to the blasthole walls. Accordingly, the interaction of explosive energy transferred to the rock mass from the blasthole was examined as a function of distance to the fault plane. A Mohr–Coulomb material model was used for host rock to allow for plastic failure calculations. The study can be divided in two parts: firstly, surface blast and secondly, underground blast. The conducted numerical study describes the role of fault in blasting in a qualitative manner. On the other hand, a free-face boundary was considered as a common blast operation which is conducted in surface mining. In second part, blast was modeled in underground operations at presence of in situ stresses. The results in such areas showed predominant effect of pre-stresses as well as fault orientation on fracture propagation.