Study on advancing rate of steeply inclined extra thick coal seam in rock burst mine based on loading unloading response ratio

It is easy for over high advancing rate of working face to induce dynamic disasters such as rock burst. To explore the reasonable advancing rate of working face has become the key to a safe and efficient mining of rock burst mine. Using the methods of numerical simulation，rock mechanics tests and field micro seismic monitoring，by studying the mining stress path experienced by the coal in front of the working face under the influence of the advancing rate of the steeply inclined thick coal seam，the mechanical behavior characteristics of coal samples under the advancing rate mining stress path were analyzed. The study on the change law of loading unloading response ratio of coal samples under mining stress path and the reasonable determination of advancing rate of steeply inclined super thick coal seam were completed and verified by on site engineering practice. The results show that the peak value of mining stress increases with the increase of the advancing rate of the working face in steeply inclined thick coal seam. At the same time，with the increase of advancing rate，the cyclic loading unloading amplitude of mining stress path increases，the cycle times decrease，the main influence area increases，and the action time decreases. The strength of coal samples under different advancing rates stress paths shows a nonlinear increasing trend，and its increasing range increases gradually. The failure degree，cumulative count of acoustic emission and energy of coal samples all increase with the advancing rate of stress paths. The coal sample under the stress path of 6.4 m/d obtained by analogy with the evaluation index of rock burst can be regarded as rock burst. At the same time，the loading unloading response ratio is introduced，and a reasonable method for determining the advancing rate of rock burst mine face based on the mining loading unloading response ratio is put forward. The evaluation index of loading unloading response ratio influenced by different advancing rates mining stress paths is formed，and the safe and efficient mining advancing rate of +425 m level working face is determined. The measured results of micro seismic field verify the effectiveness of determining the advancing rate of working face based on the response ratio of mining loading unloading.