Research On Deformation And Damage Of Overburden Rock And Prediction Of Surface Subsidence In Shallow Coal Seam Minin

With the engineering background of the Dabianyao Coal Mine in Shenmu City,Shanxi Province,this paper takes various research methods including site survey,physical mechanics study,theoretical analysis,numerical modeling,similar simulation and field monitoring,to take predictive research on the overburden deformation and failure and surface subsidence during shallow coal seam mining.The main results of this study are as follows:I.Based on the key stratum theory,it has been calculated and analyzed that the key stratum is medium sandstone,with thickness of 20 m,and the proportion of thickness between bedrock stratum and unconsolidated load stratum is 0.672.After field sampling,the coal sample was made into standard coal.After compression strength test,shear strength test,and extension strength test,it demonstrated the physical mechanical parameters of compression strength,extension strength,and Poisson’s ratio.II.Based on the elastic thin plate theory,the first pressure step and periodic pressure step are calculated theoretically,and the influence of the length of the working face,the thickness of the basic roof and the thickness of the overlying strata on the pressure step is analyzed.The random medium particle movement model is constructed to analyze the subsidence and horizontal movement under the condition of unit mining,and the prediction formulas of surface subsidence for semi infinite mining and limited mining are obtained.The subsidence,inclination and curvature of the working face are predicted.III.Using UDEC numerical stimulating software to stimulate the influence of the length(160m,200 m,240m,280 m,320m,360m),mining height(2m,3m,4m,5m),dip angle(0°,10°,20°,30°),the thickness of unconsolidated stratum(20m,30 m,40m,50 m,60m,70m)of working face to overburden failure and deformation and surface subsidence.IV.The mining process of working face in Dabianyao Coal Mine is simulated by a similar simulation test.By using of XTDIC three-dimension strain measurement system,it monitored and analyzed the movement of scatter points when the model was mined,and showed the characteristics of overburden deformation and failure and the surface subsidence with different advance distance.V.Through analysis of the actual weighting monitoring data of the Coal Mine,it can be seen that the interval time of periodic pressure step was about 1.3 days.And based on the daily advanced distance in the Coal Mine,it calculated the periodic pressure step is 16.7m,which is basically consistent with the results of theoretical analysis.Also,by using of GNSS(Beidou System/GPRS)full-automatic monitoring scheme,it monitored the movement of surface subsidence of Dabianyao Coal Mine in real-time,the result presented that the maximum of actual surface subsidence is 2050mm;the maximum of actual surface horizontal movement is 1488 mm.