Study on creep damage model of granite in Gaode Coal Mine

In order to study the creep properties of the surrounding rocks of Gaode Coal Mine and the damage evolution properties during loading, a graded loading creep test on granite samples was performed.Then, the improved Kachanov damage model was introduced based on the Burgers model, and the damage creep model which can describe the accelerated creep stage was established. The numerical simulation was used to compare the deformation of roadway control points with and without considering damage, and the application of damage model in practical engineering was discussed.The test results show that the long-term strength of the rock determined by radial creep is less than the axial long-term strength, and the radial creep is more sensitive than the axial creep, and when the stress level reaches the radial long-term strength, expansion begins to occur.When the stress level reached the axial long-term strength, the volume strain begins to change from positive to negative.Combined with the axial radial creep test curve, the parameters of creep damage model are identified, the decision coefficient reaches more than 0.97, the model curve is in good agreement with the test curve, and the rationality of the creep damage model is verified.The established rheological model considering the damage is much larger than the displacement without considering the damage. The maximum deformation of the damage considering the damage is about 0.055 27 mm larger than the maximum deformation without considering the damage. It is hence verified that the creep damage model can better reflect the deterioration effect of surrounding rock of roadway and has important guiding significance for the later support and safety of roadway.