Study On Mechanical Model Of Stability Of Aquifuge In Strip-backfill Of Shallow Seam

Water conservation mining is an important issue for sustainable development of coal inwestern shallow seam of China’s large coal fields.Not only special water conversation miningis one of the difficult technical problems of current mining industry in spacial waterconservation area of shallow seam, but also it is the key point for realizing water conservationmining. The strip-backfill mining, protecting the watertightness of gob roof, is an effectiveway to realize special water conservation mining. shallow seam mining. Therefore,researching and establishing mechanical model of the law of mined water resisting property instrip-backfill of shallow seam is of great significance. The studies have theoretical andpractical significance to promote the implement of water conservation mining in area withfragile ecology, Northern Shaanxi.In this paper, base on the different combinations of roof in special water conservation area,we select the most unfavorable one,we got the laws of aquifuge stability through physicalsimulation, and ascertain main factors affecting the stability of aquifuge by establishingmechanical model. According to the mechanical model, upward-crevice anddownward-crevice directly influence on the stability of aquifuge.The height of upward-crevice changes in direct proportion to sign of evolution mining height and spacing distanceof backfilling,changes inverse proportion to sign of evolution maximal curvature of stratum.The depth of downward-crevice changes in direct proportion to the height of claylayer,mining height and spacing distance of backfilling, changes inverse proportion to theintensity of bedrock.It is directed against Yushenfu spacial water conservation area in Northern Shaanxi.According to the theoretical formula, reasonable spacing distance of backfilling and width ofbackfilling are detemined leech on to (height of bedrock)/(mining height) ratio. Whenmining height is3m and bedrock thickness5times and18times of the mining height, the reasonable spacing distance of backfilling is21.2m and59m, and the reasonable width offilling is93.2m and36.7m; When the mining height is4m, the bedrock thickness5times and18times of the mining height, the reasonable spacing distance of backfilling is25.8m and75m, and the reasonable width of filling is86.3m and12.5m; When the mining height is5m,the bedrock thickness5times and15times of the mining height, the reasonable spacingdistance of backfilling is28.5m and76.9m, and the reasonable width of filling is82.3m and9.6m.Among them,when the mining height is5m, the bedrock thickness18times of themining height, through the theoretical formula for determining the reasonable filling withinterval width and filling band width and physical simulation results coincide, the newmechanics model for shallow buried coal seam special water preserved mining area stripfilling and provide a theoretical basis.