Analysis Of The Stability Of Mining Face And The Movement Of Surface In Wongawilli Mining Method

With the exploitation of coal resources,Rational utilization of “three under coal” and recovery of boundary coal pillar have been the key problem to be solved.For the efficient recovery of coal under building and the control of surface settlement deformation,it is necessary to study the method of coal mining.As a new mining method,Wongawilli mining method has been successfully used in a small range of China.However,there is a lack of in-depth study on the space structure and fracture law of overlying roof,the reasonable width and the failure characteristics of various types of coal pillars.Such as unreasonable coal pillar size,oversize causes waste of resources,undersize causes instability of coal pillar and then lead to roof caving,which affect the safety of coal mining.So,this paper is aiming at No.3 coal seam of Changjialiang,using the combing of theoretical research,numerical simulation and prediction analysis,study the stress of coal pillar and roof strata movement and deformation:(1)Through the key strata theory calculate the overlying strata load,establish the mechanical structure of roof coal pillar,conclude the stress of coal pillar and key strata roof;Through establishing cusp catastrophic model,the influence factor for instability failure of Wongawilli coal pillar was derived.(2)the seam thickness,the ratio of pillar width to mining width and strip pillar width by numerical simulation are analyzed,and the optimum design scheme in the coal mine geological conditions of Chang Jialiang is obtained.(3)The ground movement and deformation after mining is predicted,the results show that the movement and deformation of ground building are within I degree,which satisfies building safe request.