Analysis of burst failure energy characteristics of mining roadway surrounding rock

Roadway failure caused by burst dynamic pressure is a typical coal-rock dynamic disaster,which seriously threatens the safe production of coal mine.In view of the frequent burst failure in the 21141 haulage roadway in Qianqiu coal mine,the energy characteristics of coal and rock mass during burst failure were studied by means of theoretical analysis and numerical simulation.On the basis of analyzing the energy characteristics of micro-seismic monitoring of typical roadway burst failure,a conventional triaxial compression test was carried out.The results showed that the maximum energy fluctuation range of microseismic monitoring before surrounding rock burst failure was small,and every occurrence of burst failure event was coupled with sharp increase in energy.The ratio of bidirectional load of specimens (axial pressure/confining pressure) had a significant influence on the characteristics of acoustic emission energy.At the same loading rate,the higher the confining pressure was,the smaller the peak energy was.Under certain conditions,the influence of disturbance loading caused by events,such as mining stress,roadway repair,blasting and so on,the bidirectional load of roadway in regional stress field was obviously changed accordingly which it may cause the morphological characteristics of plastic zone change from non-butterfly shape to butterfly shape,or leaded to the instantaneous expansion of butterfly-shaped plastic zone,thus a plenty of energy which was gathered in the surrounding rock system would be suddenly released in the form of vibrations,sound,coal and rock mass flings and induced roadway surrounding rock burst failure.In practical engineering practice,it is suggested to reduce the advancing speed of coal face,control the cutting depth of coal face and adjust the stress field of surrounding rock of roadway,so as to reduce the loading rate of coal and rock mass,prevent the occurrence of large energy events and avoid the sudden release of energy during the instantaneous expansion of the butterfly shaped plastic zone of roadway.