Experimental study on rock burst induced by dynamic load

Using the self-developed impact rock burst experimental system of State Key Laboratory for GeoMechanics and Deep Underground Engineering,the rock burst induced by dynamic load was experimentally studied,and an exper- imental method for discriminating the occurrence of rock burst induced by dynamic load was presented. The cubic sandstone with circular through hole was loaded to the stress state at the depth of 500 m,and then the dynamic cyclic loading was applied to σv direction,while the constant stress was applied to σh direction. Subsequently,the process of rock burst induced by dynamic load of roof collapse in the vertical direction in the sandstone roadway at the depth of 500 m was simulated. In the experiment,the data of force and displacement were collected by the data collection sys- tem to obtain the stress strain curve of the cubic sample,and the rock burst phenomenon of sandstone sample were re- al-time photographed to obtain the feature of rock burst induced by dynamic load. The experiment revealed that the process of rock burst induced by dynamic load experiences four stages including quiet period,particle ejection,spalling and rock burst. When the rock burst induced by dynamic load occurs,the maximum tangential stress of surrounding rock is greater than its uniaxial compressive strength by calculating,and the fragment is medium and the fine grains mainly show obvious lamellate feature. Tranagranular cracks could be observed by Scanning Electron Microscope ( SEM). And the degree of crushing in rock burst induced by dynamic load is more obvious than that in uniaxial com- pression by calculating the fractal dimensions of fragment.