近距离煤层群顶板结构及破断模型分析

通过对近距离薄煤层群不同间距下层间顶板破断情况进行分析,根据顶板厚度将近距离煤层群顶板结构分为3类:散体结构顶板、块体结构顶板及板式结构顶板。建立了不同顶板结构下的3DEC数值模拟模型,分析了不同推进距离下顶板位移及应力分布情况。模拟结果表明:散体结构顶板破坏时为散体破坏,不具有承载能力;块体结构顶板破坏时为块体破坏,表现出一定的承载能力,矿压显现不明显;板式结构顶板破坏时为板式破坏,具有较强的承载能力,并具有初次来压及周期来压特点。对官地煤矿3318工作面矿压现场实测,3318工作面直接顶初次破断来压步距约为22.3 m,平均周期来压步距约为19.8 m。实测结果与数值模拟结果相吻合,表明3318工作面顶板为板式结构。

Analysis of roof structure and fracture model of the close distance coal seam group

Through the analysis of the roof fracture between the lower layers with different spacing of the close distance thin coal seam group,the roof structure of coal seam group can be divided into three categories:loose structure roof,block structure roof and plate structure roof according to the roof thickness.The numerical simulation model of 3DEC under different roof structures was established,and the displacement and stress distribution of roof under different propulsion distances were analyzed.The simulation results show that when the roof of the loose structure is broken,the loose structure is broken and has no bearing capacity;when the roof of block structure is broken,the block structure is broken and has a certain bearing capacity,the mining pressure is not obvious;when the roof of plate structure is broken,the plate structure is broken and has strong bearing capacity,and has the characteristics of first weighting and periodic weighting.The pressure of 3318 working face of Guandi Coal Mine was measured on site,the pace of first broken weighting interval of directly roof in 3318 working face is about 22.3 m,the pace of average period is about 19.8 m.The measured results agree with the numerical simulation results,it indicates that the roof of 3318 working face is plate structure roof.