Analysis of the deformation and fracture of underground mine roadway by joint rock mass numerical model

Joints in the rock mass and rheological properties are the main contributing factors in many engineering disasters. Using the user-defined visco-elastoplastic Nishihara constitutive model based on Particle Flow Code in three dimensions (PFC3D), a jointed rock mass numerical model was built to analyze rheological properties and failure behavior of a tunnel surrounded by jointed rock mass of the Zhangjiawa iron mine, Shandong Province, China. The joint distribution law was determined from a statistical analysis of joints on the tunnel walls. Based on the tunnel joint network constructed by the Monte-Carlo method, a jointed rock mass numerical model was established. The rheological properties of the jointed rock mass were separately analyzed by the Nishihara model and the linear elastic model. According to the result from the linear elastic model, the deformation of the tunnel roof and sides did not change with time and the model did not exhibit rheological properties. In contrast, the result of the user-defined Nishihara model showed obvious creep property. The bonds of the joint faces in the jointed rock mass model were primarily destroyed by shear failure. The failure modes and deformation data for the tunnel were generally consistent with field monitoring data.