An experimental study is conducted on sandstone under different confining and pore pressures through triaxial creep tests The creep properties of sandstone under different conditions are compared and analyzed The test results show that:in the case of same confining pressure,pore pressure can increase the instantaneous elastic deformation and creep deformation but reduce the strength of sandstone.Furthermore,confining pressure has an impact on creep deformation while maintaining a constant pore pressure.Based on the classical creep model and the application of effective stress theory,a new nonlinear viscoelasto-plastic rheological model for sandstone is established,which can reflect the effect of pore pressure on creep properties and induced damage in the process of creep.The comparison between the results obtained from the modeling and those from the experiments shows that this model can describe well primary attenuation creep,steady creep and accelerated creep,and a good accord is obtained.
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