Study On Dynamic Subsidence Law Of Mining Surface Of Adjacent Working Face In Yushen Mining Area

The surface movement and deformation caused by coal mining is a complex dynamic process,and the law of surface movement under the influence of uining adjacent workin,g faces are more special.For many years,due to the limitation of deformation monitoring technology and site conditions,the research on the law of surface dynamic movement under the mining conditions of adjacent working faces is insufficient.In this paper,based on the con,tinuous observation data of GNSS,combined with computer numerical simulation and theoretical analysis of mining subsidence,the basic law of mining surface dynamic subsidence under the influence of adjacent old goaf was studied.The main contents and results are as follows:(1)The applicability of GNSS continuous monitoring system applied to the monitoring of surface movement and deformation in mining area was analyzed.Based on the statistical analysis of the GNSS continuous monitoring data of the 106 working face of Jinjitan coal mine in Yushen mining area,it can be seen that the monitoring data is stable and reliable,which can meet the relevant accuracy requirements of mining subsidence monitoring.(2)This paper studied the asymmetry and fractal growth characteristics of the surface movement of the fully mechanized face under the influence of the adjacent old goaf.Based on the analysis of the time series monitoring data of GNSS in the mining area,combined with fractal theory and numerical simulation experiments,the research shows that the subsidence and subsidence rate change of the surface points at different time scales have certain fractal growth characteristics.There is obvious asymmetry in the distribution of surface movement and deformation on both sides of the adjacent working face.The displacement deformation on the side near the old goaf are significantly greater than that on the side of the coal pillar without mining,and the maximum subsidence point of the surface is a certain distance away from the side of the old goaf.(3)The quantitative relationship between the distribution characteristics of surface subsidence and the width of coal pillars between adjacent working faces was analyzed.The mining subsidence of single working face and two adjacent working faces is simulated and analyzed by FLAC3D.The results show that under the mining conditions of adjacent working faces,there is a certain quantitative relationship between the parameter(the maximum surface subsidence offset,the inflection point offset increment,the main influence range increment,etc.)and the width of the coal pillar.The relationship can be described by a logarithmic function within a certain range.(4)According to the characteristics of the dynamic movement and deformation of the adjacent mining face,based on the piecewise knoth time function and hyperbolic section function,the prediction model of the surface movement and deformation of the adjacent mining face was constructed,including the prediction model of the dynamic subsidence of the surface,the prediction model of the dynamic horizontal movement and the prediction model of the subsidence after stabilization.The results show that each function model can basically reflect the movement and deformation characteristics of the surface points in the process of advancing the underground working face.It is suitable for the prediction of the surface subsidence under the mining conditions of the adjacent working face,and has a certain popularization and application value.