关键词:

保护层开采 , 煤层变形 , 裂隙发育 , 卸压范围 , 相似模拟

Abstract: Long-distance protective layer mining is restricted by the long distance, the small pressure relief and the construction difficulty of through-layer drilling, so it will be beneficial for long-distance protective layer mining to study overburden movement law and pressure relief range. Take 9# coal seam (outburst) and 15# coal seam (non-outburst) as mining background, this paper adopted theoretical analysis, similar simulation and field test to analyze the characteristics of "two zones" distribution in roof and gas flow law after long-distance protective layer mining, to discuss roof movement of working face and stress distribution law, and designed the mining scheme of long-distance protective layer. The results showed that the pressure relief of protected layer was mainly related to the height development of the "two zones", and the protected layer was in the bending subsidence zone in engineering mine; after the mining of the lower protective layer, “three zones” appeared above the protective layer, the difference between the curves of both sides of cut hole and stop-mining line were obvious, the subsidence of coal roof was the most obvious, the one near the protected layer roof more moderate, and the one on the upper more obvious; the abutment pressure in front of the working face of the protective layer increased firstly, then decreased and finally increased slowly with working face advancing; the stress of the protected layer increased slowly firstly, then decreased and finally increased slowly with working face advancing; during the mining of the protective layer, the periodic weighting was obvious, and the average collapse step of periodic weighting was 17 m, the fracture development zone formed to trapezoid as working face advance 243 m, the upper caving Angle is 69°, and the lower caving Angle 62°; 9# coal gas could be extracted from the 15# through-bed drilling, the gas extraction concentration had a slight decline trend with the increase of time, the gas concentration dropped to 3.8% in day 65, and the extraction effect was significant.