Study on ground pressure and control technology of a fully mechanized top coal caving longwall face passing a pre-driven roadway

By means of numerical simulation and theoretical analysis,this paper studies the front abutment pressure distribution,coal stability and the main roof failure characteristics when the working face passes through a pre-driven roadway.The results show that the surrounding rock of the pre-driven roadway is severely damaged due to the high front abutment pressure.The main roof breaking mechanical model was established based on Winkler elastic foundation beam theory,and the main roof bending moment equation above the empty roadway solved,which reveals the phenomenon that the roof of pre-driven roadway factures in front of the working face.The wider the pre-driven roadway is,the farther the main roof fracture of occurs in front of the working face.During the advancing process of the working face,the main roof deviatoric stress J₂ in front of the working face presents a double peak distribution.The closer the working face to the pre-driven roadway,the higher the main roof J₂ peak value and the greater the distortion energy.The numerical simulation suggests that high water material filling support can effectively avoid the main roof fracture in front of the working face and maintain the stability of the pre-driven roadway.The zoning controlmeasures for high water material filling and double timber crib support are formulated.Field monitored data shows that the working resistance of the hydraulic support is within the safe range during the process of the working face passing through the pre-driven roadway.The study provides a reference for the control of roadway surrounding rock and roof with a fully mechanized caving longwall face passes through a pre-driven roadway.