Triaxial creep damage characteristics of sandstone under high crustal stress and its constitutive model for engineering application

The creep characteristics of rock under high crustal stress are of important influence on the long-term stability of deep rock engineering. To study the creep characteristics and engineering application of sandstone under high crustal stress, this study constructed nonlinear creep damage (NCD) constitutive mode based on the triaxial graded loading-unloading creep test of sandstone in the Yuezhishan Tunnel. A numerical NCD constitutive model and a breakable lining (BL) model were developed based on FLAC3D and then applied to the stability analysis of the Yuezhishan Tunnel. Based on the creep test results of sandstone, a power function of creep rate and stress level was constructed, by which the long-term strength was solved. The results show that the long-term strength of the red sandstone based on the related function of the steady-state creep rate and stress level is close to the measured stress value in engineering. The NCD model considering damage factors reflects the instantaneous and viscoelastic plasticity deformation characteristics of the red sandstone. The numerical NCD constitutive model and the BL model can reflect surrounding rock deformation characteristics and lining failure characteristics in practical engineering. The research results provide theoretical references for long-term stability analysis of rock engineering and the deformation control of surrounding rock under high crustal stress. The creep damage characteristics of deep rock are analyzed in this paper. The secondary development of numerical models provides a new method for long-term stability analysis of deep rock engineering. image The creep of sandstone has obvious nonlinear viscoplastic characteristics. The long-term strength of rock can be solved by a steady-state creep rate. The numerical nonlinear creep damage (NCD) model can well simulate the creep characteristics of the rock. The breakable lining (BL) model can well simulate the failure characteristics of the lining. The NCD and BL models can be used to analyze the stability of deep rock mass engineering.