Study of anisotropic creep behavior of fractured granite

Due to the heterogeneity of rocks and the complex environment around rock mass,rock mass always presents anisotropic creep behavior in the loading process.In order to describe the anisotropic creep behavior of rocks,a viscoplastic fluidity parameter tensor is proposed;and the anisotropic visco-elastoplastic creep model of fractured rock is developed.The rock matrix and fracture are represented by introducing statistical distribution and weak element,respectively.A cellular automaton creep updating rule is established.This model is integrated into the EPCA3D and a numerical system EPCA3D-EVP to simulate the creep failure process of heterogeneous rocks is compiled in VC++ environment.The model and numerical method are validated against creep tests of fractured granite,which comes from the nuclear waste underground disposal candidate site in Beishan,Gansu province,China,with consideration of hydro-mechanical coupling effect.It is found that,larger lateral creep deformation of fractured granite under the effect of seepage,compared with the situation in dry condition.The EPCA3D-EVP system is used to simulate the creep test process.It is found that the simulated results are in well agreement with experiments,indicating that the developed model can well reflect the anisotropic creep phenomenon of fractured granite under the hydro-mechanical environment.The developed model can be used to long-term stability analysis of rock mass under complex conditions.