Taking rockburst occurrence in a large-scale stope under extra-thick key strata in Shaanxi Province as the engineering background,mining-induced seismicity in extra-thick key strata and rockburst in longwall faces was investigated.During the recovery of the 4th and 5th longwall faces,min-ing-induced seismicity gradually arose and eventually covered the whole extra-thick key strata.Rockburst occurred in the middle area of the 4th and 5th longwall faces along the strike direction,and high-energy seismicity was detected simultaneously.The collapse behavior,roof strata structure,and abutment stress evolution of the large-scale stope under extra-thick key strata were analyzed,and the effect of extra-thick key strata on the static and dynamic stresses of surrounding rock was revealed.The following beneficial results were obtained.With the recovery of the 4th and 5th longwall faces,primary and secondary extra-thick key strata break,respectively,and a large-scale cantilever-articulated beam structure is formed in the roof.This structure serves to bear the overburden load and shifts it to the adjacent coal and rock mass,leading to a notable increase in the static stress there.Under mining disturbances,multiple rock strata in the large-scale cantilever-articulated structure break collaboratively and trigger high-energy seis-micity,which exerts dynamic disturbances on the overstressed coal and rock mass and significantly pro-motes rockburst risk.Accordingly,a strategy for prevention and control of rockburst by deep-hole pre-splitting blasting was proposed.The monitoring results indicate a remarkable decrease in both the periodic weighting distance and the mining-induced seismicity intensity,demonstrating that the strategy succeeds in effectively lowering rockburst risk.
关键词
冲击矿压/巨厚关键层/动静载应力/覆岩结构/深孔预裂爆破
Key words
rockburst/extra-thick key strata/static and dynamic stress/overburden structure/deep-hole pre-splitting blasting
维普
万方数据