Study On Overburden Movement And Surface Movement Under Water Loss Mining In Thick Loose Aquifer

There are thick loose strata in the vast areas of China,and there are loose layers of different thicknesses in the mining areas of Northeast China,North China,Central China and East China,and there are Quaternary aquifer sandstones in the plain areas of North China,Northeast China and East China.Coverage,coal mining activities in these areas have problems with coal mining under aquifers.In order to alleviate the contradiction between coal production and social life,and avoid the waste of a large amount of coal resources in the "three downs",it is necessary to rationally develop and utilize the coal under the thick loose aquifer.This paper takes the 11111 working face of Pansidong Mine as the engineering background.According to the mining data of hydrogeology and other mining materials,the monitoring data of surface observation stations and the numerical simulation test of similar materials,the main research is on the overburden movement and surface movement under the conditions of water loss in thick loose aquifer,law.The main conclusions are:(1)Organize and analyze the observation data and draw the movement deformation curve,and obtain the angle parameter.The 11111 working face has a boundary angle of 57.57°,the upper boundary angle is 48.71°,the strike angle is 66.28°,and the uphill moving angle is 70.000.(2)Calculate the predicted parameters of surface movement deformation,the sinking coefficient q is 1.20,the main influence tangent value tanp is 2.55,the horizontal movement coefficient b is 0.14,the offset to the inflection point is 27.6m,and the offset distance of the uphill inflection point is-20m,the influence propagation angle is 85.920.The characteristics of the predicted parameters under the action of thick loose aquifers are mainly due to the large subsidence coefficient and the small horizontal movement coefficient.The measured and predicted values are compared and the working surface sinking contour is drawn.The expected results are in good agreement with the measured values,indicating the reliability of the parameters.(3)The residual value of the sinking amount obtained by the digital displacement extraction method is distributed in the range of-0.8mm to 0.8mm,and the average error is 0.344mm.The errors in the observation lines No.1,No.2.No.3,and No.4 are 0.077 mm,0.085 mm,0.097 mm,and 0.094 mm,respectively,and the errors in the observation points on the observation lines No.1 and No.2 with larger settlements are compared.Small,indicating that the amount of settlement has a certain influence on the digital displacement extraction method.(4)When the working surface is advanced to 50m,the top plate is pressed for the first time.After the mining is completed,the front slump angle is 57°,the rear slump angle is 62°,the slump band height is 25 m,and the crack band height is 38 m.In different rock layers,as the distance from the mining coal seam increases,the subsidence value increases gradually.In the same rock stratum,with the progress of coal mining activities,the overburden continuously moves and deforms,and the nearest observation line above the coal seam appears.The jump change,the sinking point of the observation point on the observation line No.2 above the coal seam gradually increases with the advancement of the working face.(5)The observation lines of No.3 and No.4 above the aquifer have a large difference in the amount of subsidence in the case of water loss and no water loss,and are in the vicinity of-25 to 25 m from the open cut and 25 to 25 m from the stop line. The sedimentation difference is a minimum of 34 mm and a maximum of 328 mm.The difference in sinking amount is about 105 mm and the maximum is 1554 mm at a distance of 25 to 175 m from the open cut.In the state of water loss,the sinking coefficient of the No.4 observation line above the aquifer and the working surface advancement distance are satisfied:y=0.00505x-0.16115(y indicates the subsidence coefficient,x indicates the working surface advancement distance),and the fitting degree R2 is 0.92661.Fig[34]Table[11]Reference[81]...