Three-Dimensional Creep Constitutive Model of Transversely Isotropic Rock

Abstract

Transversely isotropic rock is a typical anisotropic rock type. The existing creep constitutive models for isotropic rock do not fully reflect the creep mechanical properties of transversely isotropic rock. By considering a set of creep parameters as the internal connection among the rock specimens with different bedding directions, a three-dimensional creep constitutive equation of transversely isotropic rock is derived, which can effectively describe the characteristics of the instantaneous strain, decaying creep, and steady creep of a transversely isotropic rock. A method to determine the creep parameters for the three-dimensional creep constitutive model is proposed. Based on the creep test experimental data of horizontally orientated and vertically orientated phyllite, the transversely isotropic creep properties and creep parameters are successfully identified using the proposed method. The rationality and validity of the new model are certified by comparing the theoretical curves with experimental data. The results of this paper provide a new approach to study the three-dimensional creep mechanisms of rock and provide scientific research support for the design of rock creep tests.