Study and application of short-wall gangue cemented backfilling technology

In terms of the problems of large amount of coal buried in "three unders", huge costs of relocation, large investment with longwall filling mining and mutual interference between mining and filling in China, through theoretical analysis, laboratory test, numerical simulation and field measurement method, the authors put forward the short-wall gangue cemented backfilling technology, through analyzing the ratio of backfill material, branch roadway stability and the change of stress field in surface subsidence control.Some conclusions can be drawn as follows:① The best filling slurry ratio is 1:1.5:4, and slurry and gangue mixed with ratio 1:2 to fill branch roadway; ② The best branch roadway width is 5 m with ultimate strength theory; ③ Numerical simulations show that the stress peak value is 13.1 MPa, the initial stress of filling body is 1.6 MPa, the final stress is 10.4 MPa, the plastic zones is in the range of 0-5 m, the floor failure depth is 0-5 m with W-wave shape distribution; ④ Field measurements show that advance support pressure peak is 19.7 MPa in front of 4.6 m of branch roadway, the maximum displacement with top and bottom is 116.3 mm; overburden in the range of 0-5.7 m produced a small amount of cranny without obvious delamination, and the roof rock stratum only occurs in the curved lower layer without caving zone; ⑤ The source of filling materials sourced in low cost, the gangue transportation distance is short, and a mining and filling parallel operation is achieved.The method has been widely applied in Inner Mongolia Yuxing coal mine and alleviated the disadvantages of longwall filling mining.The maximum economic and environmental benefits are obtained with the minimum unit cost, which has a great significance to "three unders" mining.