A review on hard roof rock burst prevention and control by backfill technology

With the gradual increase in the depth and intensity of coal mining in China,the threat of rock burst to thesafety and efficient production of coal mines is becoming increasingly severe. While backfill mining technology can re-alize green mining by restricting overburden movement through backfill body in the goaf,which can prevent rock burstaccidents induced by hard roof. Focusing on the prevention of hard roof induced rock burst by backfill mining technol-ogy,this thesis reviews the research progress of dynamic characteristics of backfill body consisted of loose backfill ma-terials and cemented backfill materials from three aspects:the dynamic characteristics,energy transfer mechanism andrelevant numerical simulation. At present,the research on the dynamic characteristics and energy transfer mechanismof granular filling materials and cemented filling materials is mainly conducted by using drop hammer impact test andHopkinson pressure bar test. PFC and ANSYS are widely used to study the dynamic load characteristics of backfill ma-terials. It is concluded that the mechanism of rock burst induced by hard roof is that the sudden collapse of roof causesrapid release of accumulated energy in roof and coal seam,and then causes rock burst. From the point of view of fillingrate and energy mechanism, the interaction mechanism between hard roof and backfill body is expounded. It isrevealed that backfill body can effectively reduce energy accumulation,slow down energy release and reduce energytransfer efficiency in coal strata,and its effect mainly depends on the filling rate. This thesis also elaborates on the sol-id backfill and cemented backfill mining technology for the prevention and control of hard roof induced rock burst. Theengineering cases of solid backfill in the 6304 working face of Jisan Coal Mine and cemented backfill in the 1123working face of Gucheng Coal Mine is analyzed. The measured microseismic data show that the filling mining technolo-gy can obviously reduce the frequency and energy level of microseismic events in the mining process of the workingface,and can effectively prevent the occurrence of rock burst of hard roof type. In the future,the rock burst preventionand control by backfill mining technology will require in-depth research in basic theories such as:studying the move-ment and energy evolution of rock strata,achieving precise control of rock strata and accurate prediction of energy evo-lution,and developing new energy absorbing backfill materials for reducing rock burst impact.