Study On The Law Of Surface Movement And Deformation Due To Deep Mining In Mountainous Area

Underground mining of coal will cause overlying rock strata to move,break and deform,resulting in significant surface subsidence.The first panel of a mine in Qinshui coalfield is located in a mountainous area.The surface movement and deformation caused by coal mining in this area will not only produce a large number of surface cracks,but also the connection and extension of surface slope cracks may induce slope slip,which makes geological disasters such as landslides more likely to occur.At the same time,the size of working face and the width of coal pillar are different,which makes the law of surface movement and deformation become more complicated.Therefore,it is of great practical significance to study the surface movement and deformation law of deep mining in this area to evaluate the influence degree of coal mining on surface buildings in mountainous areas and to guide the prevention and control of surface landslides.Based on 1311 working face of the panel as the research object,surface movement deformation caused by mining of 1311 working face was measured,using numerical simulation method to explore the mountain terrain to the influence of the mining surface movement deformation regularity,the size of the working face and coal pillar width the impact on the mining surface movement deformation rule,obtained the following results:(1)The law of the mountain surface subsidence after 1311 working face mining was measured,and the subsidence,inclination and subsidence velocity of the surface after 1311 working face mining were analyzed.On this basis,combined with the subsidence prediction results,the mining surface movement and deformation parameters of 1311 working face were obtained: After the mining of 1311 working face is finished,the maximum affected area reaches about 396 m,and the boundary angle affected by mining is about 53°;according to the monitoring results of Y4,the leading influence distance is 92 m and the leading influence angle is 83°;the hysteresis distance of the motion trajectory inflection points of Y1,Y2 and Y3 is between 215 m and 285 m,and that of Y4 is 185 m.(2)Using UDEC numerical simulation method,the law of surface movement and deformation of coal seam mining under the conditions of different slope shape,different working face advancing direction and different working face position were studied:when mining under different slope forms,the surface movement and deformation law is affected by mining subsidence and slope slippage;the slope body is more stable when mining along the slope than when mining against the slope;the fundamental reason for the difference of surface movement and deformation caused by different working face positions is the different slip degree of different slope parts(3)The influence law of the size of working face and the width of coal pillar on surface subsidence was revealed,and the internal relationship between the change of the size of working face and coal pillar and surface subsidence was analyzed from the perspective of stress and fracture: due to the increase of the mining width of 1311 working face and the decrease of the coal pillar size,the stress around the coal pillar in the section increases,which further promotes the compaction and closure of the fractured area in the overlying strata.Finally,the subsidence will continue to increase when the surface reaches the full state.This paper has 79 pictures,10 tables,and 55 references.