Study On Induced Mechanism Of Roadway Floor Rock Burst Under Super-thick Conglomerate Stratum

Based on the research on rock burst occurrence characteristics and cause of formation in Qianqiu Coal Mine, through rock mechanics experiment, similar simulation test, numerical simulation and theoretical analysis methods, rock burst induced mechanism of thick coal seam roadway and the overlying super-thick conglomerate stratum movement influence on rock burst induced factors were researched. Research results can provide the theoretical basis for prevention of rock burst under similar conditions.Based on analysis of the lower roadway rock burst occurrence characteristics during roadway tunneling and face mining of 21 mining district in Qianqiu Coal Mine, coal mine geological factors(CMGF) and mining technology factors(MTF) influence on rock burst formation were researched. CMGF are the intrinsic factor of rock burst formation, provide the basic conditions for rock burst formation. MTF are the inducing factor of rock burst formation, disturbance of tunneling and mining broke limit stress equilibrium state of rock burst scene, result in rock burst to start. High stress concentration during tunneling and mining of the lower roadway located in the middle of isolated island working face is the main factor of rock burst induced.Through coal and rock physics mechanics test, uniaxial compressive strength(UCS) and effective burst energy velocity index(EBEVI) have been as burst tendency differentiation index. Five indices which are dynamic failure time, burst energy index, elastic energy index, UCS and EBEVI are as burst tendency differentiation index system of 2# coal seam in Qianqiu Coal Mine. These indices considered impact energy and time effect of coal sample deformation and failure process, strength index etc., could enhance the reliability of the discriminates results.This paper studies movement law of overlying super-thick conglomerate stratum and its influences to rock burst induced factors. super-thick conglomerate stratum movement causes of rock burst influence of static load and dynamic load disturbance are considered.Regularity of thick coal seam roadway floor bust under dynamic load disturbance when super-thick conglomerate fracture are reproduction.Causes of roadway floor burst failure by theoretical analysis; horizontal stress is the main factor of induced floor rock burst. Theoretical calculation method of the maximum horizontal stress was put forward. Floor burst induced mechanism model and floor strata yielding-rupture mechanical calculation model have been attained. Roadway effective width and floor strata slice height influence on the minimum horizontal stress that results in floor strata yielding-rupture were researched. And floor strata yielding-rupture criterion that index as floor strata slice height was established.Through in-depth digging influence factors of rock burst risk, according to highly complicated nonlinear relationship of rock burst risk evaluation and its influence factors, random forest model of rock burst risk assessment is established by introducing random forest theory.