Nonlinear creep damage model of rock salt considering temperature effect and its implement in FLAC3D

Laboratory tests were carried out to study the effect of temperature on the long-term strength of rock salt, the creep modulus was defined and the evolution equation of creep thermal damage of rock salt was established. Based on the creep test results of rock salt, a nonlinear thermal visco-plastic damage model considering the influence of temperature damage and expressing the accelerated creep behavior of rock salt is established. According to the construction method of nonlinear creep model, a new nonlinear visco-elastic-plastic creep damage model considering the influence of temperature (nonlinear T-VEPD creep model) is established by concatenating the nonlinear thermal visco-plastic damage model with the Burgers creep model. And then the parameter inversion identification of the model, the results show that the model can well describe the creep properties of rock salt. The finite difference expression of nonlinear T-VEPD creep model is derived by using finite difference theory. The dynamic link calculation program (.dll) of the model is obtained by using the programming and FLAC3D secondary development interface, and then the creep model is verified by laboratory test simulation.