Research On The Deformation And Destruction Law Of Overlying Strata Of Solid Waste Compacted Backfill-mining In Coal Seams With The Condition Of Thick Unconsolidated Layers And Thin Bedrock

The controlling ability of the thin bedrock under thick unconsolidated layers to the coal roof is weak. Therefore, the deformation and destruction law of overlying strata presents as a certain particularity. According to the traditional caving mining experience, strata behaviors of the coal roof are severe, and Roof accidents can be caused. If the thick unconsolidated layers are water-cut, a risk of water or sand collapse may come into being. However, research findings about solid waste compacted backfill-mining in thick unconsolidated layers and thin bedrocks area are not too much. By summing up and summarizing the results of previous studies, this paper studied the deformation and destruction law of overlying strata with combining methods of theoretical analysis, numerical simulation and engineering practice, and drew the following conclusions:(1)Based on equivalent mining theory, got the development height experience formula of the water flowing fractured zone, and by establishing a mechanics simplified analysis model of the overlying strata above goaf in the thick unconsolidated layers and thin bedrock area, got the relationship between development height of thin bedrock beam and filling rate.(2)By using L9(34) orthogonal test, analyzed the influence degree on the deformation and destruction law of overlying strata of 4 factors, and the sequence is filling rate、thickness of unconsolidated layers、mining thickness、thickness of bedrock in decline order.(3)Afer establishing numerical model of caving mining and filling mining, deformation and destruction law of overlying strata were impared and analyzed, from the aspect of stress of surrounding rock, movement and deformation of surrounding rock, development of plastic zone. The results showed that:Compared to that of traditional caving mining, when adopted filling mining scheme the controlling effect of abutment pressure surrounding rock was much better, and deformed stress recovery area. At the same time, the movement of surrounding rock was obviously decreased, and the water flowing fractured zone was not penetrated through the aquifer under the unconsolidated layers.(4)Launched an industrial test on 5104 working face, the observation results showed that:There was no caving zone in overly strata above the goaf after solid waste compacted backfilling, and the roofkept great integrity, no first weighting, no periodic weighting, thus the surface buildings was affected lightly.In conclusion, the research results can provide a theoretical guidance, which is also of a guided significance to the water-preserved minings safety mining and green mining with the condition of thick unconsolidated layers and thin bedrock.