Study On Ground Deformation Law In Changping Mining Area

China has a large population and a large demand for energy.With the development of science and technology,coal mining is becoming easier and easier.Moreover,coal mining enterprises are not conscious of environmental protection and unreasonable mining,which not only causes environmental pollution,but also causes surface deformation and destruction by underground coal seam mining,and causes serious losses to people’s production and life.Therefore,in order to fully understand the relationship between goaf and surface deformation,it is necessary to speed up the study of the law and characteristics of surface subsidence caused by underground mining.Based on the actual ground investigation in research area,the ground deformation disasters occurred in the study area have been counted,sorted out and analyzed.And summarized the overall ground deformation characteristics in the study area: easy to cause water accumulation in collapse pits,greater threat range,The ground subsidence deformation is mainly slow sinking,and there is basically no possibility of sudden collapse.This paper also predicts the possible ground deformation caused by No.9 and No.15 coal seams in Changping Coal Mine by calculating probability integral method and establishing numerical model with FLAC software: the maximum surface subsidence displacement caused by the excavation of No.9 coal seam is 1.04 m,the horizontal displacement has a maximum positive value of 0.33 m and a maximum negative value of 0.35 m.No.15 coal seam was excavated after No.9 coal seam was excavated and surface subsidence was stable.The maximum surface subsidence displacement caused by the excavation of No.15 coal seam is 1.49 m,the horizontal displacement has a maximum positive value of 0.49 m and a maximum negative value of 0.53 m.Surface deformation displacement are in agreement with the results of probability integral method,this provides a reference for engineering construction and goaf management.In this paper,two main factors affecting the surface deformation of goaf are analyzed: the ratio of mining depth to thickness and the scale of goaf,and the influence laws of each factor on the surface deformation are obtained.(1)When the thickness of coal seam is constant,Surface deformation displacement decrease with the increase of mining depth.When the mining depth is fixed and the mining thickness increases,Surface deformation displacement gradually increase with the increasing thickness of the mining.When the depth and thickness are different,but the mining depth-thickness ratio is the same,and the ratio of mining depth-thickness ratio is less than 30,the maximum subsidence displacement decreases gradually with the increase of mining depth and mining thickness;When the mining depth-thickness ratio is greater than 30 and the mining depth-thickness ratio is the same,with the increase of mining depth and mining thickness,the surface subsidence displacement value is small,but it increases gently.(2)When the goaf is rectangular or square,the form of expression on the surface always tends to be circular or elliptical;When mining depth and thickness are fixed,the maximum subsidence displacement increases with the increase of mining scale;With the increase of mining length or width,the maximum surface displacement increases gradually.Understanding the deformation law of the goaf will help us reducing and controlling the geological disasters caused by the goaf,which is of great significance to our construction and green development.