蠕变-循环作用下粉砂岩力学响应及损伤演化特征研究OA

To address rock mass damage induced by the changes of load state of surrounding rock from primary mining to secondary mining,uniaxial compression tests were conducted under different creep stress levels and cyclic loading and unloading combinations.The mechanical properties and acoustic emission characteristics of siltstone under the combined action were investigated.The results show that different creep stress levels will change the initial damage state of rock and significantly affect the energy dissipation in the subsequent cyclic loading and unloading process.The uniaxial compressive strength of siltstone decreases with the increase of creep stress level,and the compaction stage is shortened and the elastic stage is prolonged in the uniaxial stress-strain curve.The acoustic emission signal shows that the initial damage induced by creep promotes the transformation of acoustic emission behavior from Kaiser effect to Felicity effect.Through RA-Fa crack analysis,the rock failure in the later stage of loading is dominated by tensile cracks.The piecewise nonlinear damage model based on statistical damage mechanics can better characterize the damage evolution process at different loading stages.The research conclusions provide a reference for the long-term stability evaluation of surrounding rock mass.