Experimental study and constitutive modelling of rock dilatancy–bulking behaviour

Abstract

The process of stress induced fracturing around underground excavations is associated with dilatancy–bulking behaviour of the failed rock. Owing to its importance in earth science and engineering design, this paper presents an experimental investigation of rock dilatancy–bulking behaviour based on unloading tests carried out on the rock samples from the Gubei colliery. The experimental results were evaluated to determine the damage dilatancy stress and peak stress from the stress–strain curve. Then, combining damage dilatancy yield criteria and fracture yield criteria, a RDPF model, which can simulate both pre‐peak damage dilatancy and post‐peak fracture bulking characteristics of rock, has been developed and implemented into the distinct element code UDEC. The proposed model accounts for the evolution of the strength parameters, and describes the property of pre‐peak inelastic deformation and post‐peak strain softening. The results of numerical simulation obtained on the basis of this model are compared well with the corresponding experimental results, which prove that the constitutive law is reasonable and effective in simulating the failure of rock under unloading conditions. Moreover, the proposed RDPF model was applied to the evaluation of an excavation damage zone around a deep roadway for the purpose of checking the performance of the model. The pre‐peak damage dilatancy zone and post‐peak fracture bulking zone can be distinguished effectively by the proposed model, which is significant to stability analysis and maintenances of deep roadways.