Evolution Law ofHysteresis Curve ofRock under Cyclic Loading

To investigate the deformation behaviors ofrock the evolution of the hysteresis curve ofrock under cyclic loadingwas studied by the experimental investigation of the deformation characteristics of fine sandstone under cyclic loading at three deformation rates and two stress levels. The research shows that the deformation curve of fine sandstone under unloading does not coincide with the deformation curve for loading to result in a hysteresis curve in the deformation curve, and the hysteresis curve is nearly unchangeable since the 2nd cyclic loading ata low stress leve.l In addition, fitting parametersof deformation curves for the 1st cyclic loading are different from those for the 2nd cyclic loading at different stress levels and deformation rates, but they tend to be unchanged gradually since the 2nd cyclic loading. Furthermore, the responses of rock deformation to differentdeformation rates and stress levels under cyclic loadingwill be differen,t and the fitting parameters change with deformation rates and stress levels.