Stability analysis of fractured rock mass around underground excavations based on a three-dimensional discrete fracture network

Underground excavation often encountered rock masses embedded with pre-existing fractures. Conventional excavation analysis was generally based on a continuum description. In this study, to investigate the influence of randomly distributed discrete fractures on underground excavation, a finite element modeling approach based on a three-dimensional (3D) discrete fracture network (DFN) was utilized. The influence of fracture parameters including fracture intensity, dip angle and strike on the surrounding rock stability was considered in the simulation. The results suggested that fractures caused complexity in terms of the deformation behavior of rock masses around the underground cavern, facilitated the instability of surrounding rock. The intensity, dip angle and strike of fractures had different effects on the stress, displacement and failure modes of the jointed rock masses. The fracture intensity mainly affected the magnitudes of the induced stress and displacement of surrounding rock masses: a larger stress concentration and heterogeneous distribution were more likely to occur in rock masses with lower fracture intensity. While the dip angle and strike of fractures showed more impact on the distribution of displacement and failure modes of surrounding rock masses, especially for those on the roof and sidewall.