Study On The Waste Backfill-mining Method With Back Forward Style And Relevant Laws

On account of a series of economic and enviromental problems that the low coal recovery ratio and serious enviromental pollution caused by that many coal reserves are trapped under building structure, railway and water body and the large amount of raw waste are discharged in Chinese coal mines, combined with Xiezhuang coal mine pratical productive geological condition, waste backfill-mining method with back forward style was studied and determined. It has many advantages, such as high production efficency, simple production system and low filling cost and so on, which is a new high production and high efficency mining technology to mine "three under, one above" trapped coal reserves.Key issues for the raw waste backfilling are how to control strata movement by backfilling waste to make sure that ground deformation within the allowable range and reduce the depth of destroyed floor caused by mining. According to the dominant stratum theory and waste filling theory, this paper studied the rules of overlying strata movement and surface deformation by comprehensive use of methods and means of theoretical analysis, numerical simulation and field mesurement. The results indicate that bending subsidence of key stratum and ground deformation are effectively restrained using the waste backfilling.Based on the the study of ovelying stratum movement, by using of the theoretical reseach and numerical simulation, It studied the evolution law of stress and displacement and deformation failure characters of surrounding rock of gob-side roadway retaining with forward style under the filling condition. Through the reseach, it can reduce the time and degree of rheological and suffering mining influence of roadway's surrounding rock adopting the technology of gob-side roadway retaining with forwar style under the condition of filling-mining. So it can well control the deformation of retaining roadway.At last, floor stress distribution are reseached by theoretical calculation method under the filling-mining condition, the influence laws of floor failure at different filling parameters are studied and analyzed under the filling-mining condition by numerical simulation. Then it is proved that waste filling-ming can reduce effectively the depth of floor failure by the method of field measurement, which provides a new mining basis and method for coal mining above confined aquifer..