Abstract:
Due to the different strength of coal seam roof, the creep characteristics of rock mass after crushing are different, which leads to the different long-term deformation laws of goaf. In response to this issue, similar material model tests are used to make similar test models of three kinds of fractured rock masses with different strengths with the same gradation and carry out creep tests. By analyzing creep curves of fractured rock masses with different strengths under different creep loads, creep characteristics of fractured rock masses in caving zones with different roof strengths are revealed. The results show that the initial creep rate and the stable creep rate of fractured rock mass with different strength decrease with the increase of load, and the deformation rate adjusts quickly in the initial creep stage. With the increase of time, the steady creep rate gradually becomes stable and reaches steady creep. The initial creep rate of medium and hard rock has a peak value and then decreases with the increase of load, which indicates that under this specific load, particles of medium and hard rock are broken and rearranged during the loading process, while soft and hard rock do not have this feature. The medium and hard rocks show a certain fluctuation before reaching the steady creep stage, while the steady creep rates of soft and hard rocks decline steadily.