Law of overburden and surface deformation in roof cutting and backfilling mining under thin bedrock in shallow buried coal seam

Abstract

Abstract Under the special geological conditions of shallow buried coal seams and thin bedrock, the caving method of coal mining can cause irreversible damage to the ecological environment such as the aquifer structure, surface subsidence, and ground fissures of the mine. However, the traditional backfill mining has problems such as insufficient material, low efficiency, and high cost. The paper focuses on the new ideas of roof cutting and backfilling mining treatment, taking Jinjie Mine as the research background, through theoretical analysis, similarity model experiments and numerical simulation, the laws of overburden failure and surface movement and deformation under shallow buried and thin bedrock geological conditions were studied when using roof cutting and backfilling mining method. The comparative study with the fully mechanized caving mining method shows that the use of roof cutting and backfilling method can suppress the development of fractures and achieve the effect of reducing subsidence. Before releasing the constraint of the filling gangue column, the maximum direct roof subsidence of the coal seam reached 375 mm, and the maximum surface subsidence value reached 263 mm. After releasing the constraint, the maximum direct roof subsidence of the coal seam reached 541 mm, and the maximum surface subsidence value reached 403 mm, which is much smaller than the subsidence value of 2804 mm in the caving mining method. A visual simulation study was conducted on the whole backfilling mining using numerical simulation software, which confirmed the conclusion of similar model experiments that the roof cutting and backfilling mining method can effectively control the overburden failure and surface subsidence.