Impact law of the bulk ratio of backfilling body to overlying strata movement in fully mechanized backfilling mining

Fully mechanized backfilling mining technology with waste, fly ash, and loess, etc. provides advantages of safety and high efficiency to the extraction of coal under buildings, railways and water bodies. In this paper, the bulk ratios of backfilling bodies with different waste and fly ash mixture ratio was analyzed with MTS815.02 electro-hydraulic servo rock mechanical testing system and compacting device, the optimal mixture ratio of waste and fly ash was determined, and it proposed that the backfilling body should be firstly compacted after being backfilled into the goaf. With numerical simulation, the impacts of bulk ratio of waste and fly ash backfilling body to overlying strata movement law and surface subsidence controlling in backfilling mining were analyzed, and it figured out the bulk ratio of backfilling body that could ensure a reasonable range of surface subsidence. Finally, the engineering application confirmed that the strata movement controlling in fully mechanized backfilling mining was more effective, the surface buildings and facilities were not severely influenced. The above achievements could provide technical reference for the successful implementation of fully mechanized backfilling mining.