Basic Study On Flexible Strip Filling In Water Preserving Mining Of Shallow Seam

Jurassic coalfield in northern part of Shanxi is the largest proved coalfield of our country,of which the proved reserves is1400million tons. The coalfield locates in contiguous areabetween desert and loess plateau and the earth’s surface ecology environment is fragile, thereis widespread Quaternary Salawusu Formation aquifer underground. The mining scale ofcoalfield is very large, the overlying strata of coal seam is thin, causede the loss of phreaticwater and serious damage of environment on surface. Now, the water-preserved miningmethod in special water-preserved mining area has not been solved, studying the Subsidencereduction mechanism of low-cost flexible strip filling and building the strip fillingwater-preserved mining methods, have important significance in theory and practice.This paper uses the method of combining simulated experiment and theoretical analysis,systematacially studies the geological mining conditions and the way of filling mining inspecial water-preserved mining area, analyses the engineering properties and distribution ofaeolian sand in Yu-Shen-Fu Miming Area, obtains the rational proportion scopes of sandfoundation paste material in north Shaanxi by experiment, which are like this, the massconcentration is83%~84%, slump is21.5~25cm, and28d strength is about2MPa, thenanalyses the feasibility of filling. The experiment studies the law of overlying stratamovement and fracture development, and aquifuge stability, demonstrates rational fillingparameter. The study aims at the most difficult bedrock and clay combination conditions inspecial water-preserved mining area, bases on the flexible strip filling overlying stratamovement and deformation rules and the law of aquifuge stability, builds the controlmechanics model of flexible strip filling aquifuge stability, reveals the main factors such asfilling body strength、filling parameter、the thickness and character of watertight petrofabricetc. that result in the instability of aquifuge. The study concludes that, choosing the fillingbody strength, filling location and width reasonably can control the movement of fracture old roof efficiently, avoid the tension-shear failure caused by the oversize local deformation ofaquifuge, make the aquifuge subside slowly, evenly and continuously, thereby guarantee thestability of aquifuge. At last, the aquifuge stability can be used as a criterion to build thecertain method of rational filling body width and filling location of low-strength flexible stripfilling.The paper study reveals the mechanism that we can realize water-preserved mining whenwe use low-strength, low-cost sand foundation paste materials to conduct partial filling, andthe flexible strip filling water-preserved mining method that suggested in the paper providesnew way of water-preserved mining for ecologically fragile mining area, this study hasextensive application and promotional value.