| Thin coal seam resources in China are abundant and widely distributed.However,due to the shallow burial of some thin coal seams and the thinner thickness of overlying bedrock,the mining of coal seams is easy to cause ground subsidence disaster,which is harmful to the mining environment and surrounding buildings.How to reduce the damage of mining subsidence to the surrounding environment while ensuring the safe and effective mining of thin coal seam resources has great significance.In this paper,the research object is coal mine of Luzegou in northern Shaanxi,the coal mine of Luzegou only mines V thin coal seam at the top of the Upper Triassic Wayaobao Formation,and the stratum in the study area is near horizontal stratum.Through the field survey of the subsidence in the study area and combining UDEC which is a discrete element software to conduct numerical simulation analysis of mining subsidence in the research area,this paper summarizes the characteristics of ground subsidence caused by thin seam mining in the study area,then uses probabilistic integration method to verify the results and summarizes the influence of the variation of the thickness of overlying stratum on the ground subsidence of thin seam mining in the study area.The main achievements are as follows:(1)Studying the surface subsidence after the thin seam mining by the UDEC discrete element software,it is concluded that no matter the thickness of bedrock and the thickness of loose layer,the distribution of surface subsidence curve caused by thin seam mining is similar to that of other cases.The main performance is:After fully mining the coal seam,the subsidence basin is formed above the GOAF,and the subsidence value above the center,of the Mined-out area is the largest and gradually decreases to the surrounding area;the subsidence curve is symmetrically distributed in the goaf.(2)Within a certain range,when the thickness of the loose layer remains unchanged,the maximum subs:idence of the surface decreases with the increase of the bedrock thickness,the subsidence rate from large to small,and the relationship between the thickness of bedrock and the maximum subsidence of the surface conforms to the negative exponential curve.When the thickness of bedrock remains unchanged,the maximum subsidence value of the surface increases with the increase of the thickness of the loose layer,and the maximum subsidence curve is similar to that of the logarithmic curve.(3)Through the analysis of the thickness of the overburden rock in the study area,a four-layer combination model of thin bedrock thick topsoil,thin bedrock thin topsoil,thick bedrock thick topsoil and thick bedrock thin topsoil was established.Based on numerical simulation analysis,it is concluded that within a certain working face pushing range,the thick subsidence of thin bedrock top soil model has the largest amount of ground subsidence,and the maximum value is 970mm.When the coal seam length and depth ratio is approximately 1.4,the coal seam is fully mined and sinks.The coefficient is about 0.81,and the surface subsidence development curve shows a flat bottom phenomenon.The thick-bedrock thin topsoil model has the smallest ground subsidence;the maximum subsidence is 370mm,and the strata do not sink sufficiently.The subsidence coefficient is about 0.31.(4)Within a certain range,when the thin coal seam is mined by the fully mechanized mining method,the amount of ground subsidence is related to the bedrock thickness,loose layer thickness and the ratio of earth to rock.The larger the ratio of earth to rock,the greater the amount of subsidence on the ground.When the bedrock thickness is thick,the variation of the loose layer thickness has a relatively large influence on the subsidence coefficient of ground subsidence,and vice versa.When the loose layer is thin,the change of bedrock thickness has a relatively large influence on the subsidence coefficient of ground subsidence,and vice versa. |
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