Critical Filling Height for Stability Controlling of Basic Roof Rock Stratum at Working Face

Disposing goafs with fillings is an effective measure to realize the green mining with environmental protection.Against the filling mining working face in JZEG Xingdong mine,this paper calculates the critical filling height for controlling the stability of basic roof rock stratum applying the elastic theory and the combined effect model of filling mass-immediate roof after broken expanding.Filling work at the 1126 working face in Xingdong mine was guided by the critical filling height,and roof subsidence and floor heave of coal roadway,ground subsidence of the working face were monitored in real time.The results indicate that under the condition of 2#coal seam in Xingdong mine whose average mining height is 4.5m,the critical filling height is 3.7 m,which prevents the working face roof and the strata above from breaking(the ground would not largely deform);and that the actual filling height at the 1126 working face was 4m,in which case the roof subsidence and floor heave of coal roadway were not large,obvious caving of the overlying strata did not occur.The whole mobile process of overlying strata was completed in a slowly sinking way.Ground subsidence was well controlled,with the largest surface subsidence less than 0mm,which had a slight influence on ground architectural structure.