Abstract：According to triaxial creep experimental results of hard sandstone in 2506 working face roof of Guan Yin Tang coal mine,a polynomial element is introduced to reflect creep acceleration phase. A new nonlinear viscoelastic plasticity creep model of hard rock is established by combing with the polynomial element and Poynting model. It can describe both axial and lateral creep courses. The parameters inversion of the creep model established has been done by the base of 15 MPa confining pressure and axial step loading creep experimental data of sandstone,and the creep parameters of the model have also obtained. The correctness and rationality of the nonlinear creep model are verified through curve fitting of standone three axis creep test.

Keyword：sandstone;creep;polynomial element;nonlinear creep model;parameter inversion;