Jinneng Holding Coal Industry Group Tashan Coal Mine Co., Ltd.

为研究近距离煤层上层煤采空区对下层煤采动底板破坏的影响,以塔山矿8199工作面为例,通过统计公式和塑性力学公式预计工作面底板破坏深度;采用双向加载相似模拟试验分析顶板有无采空区对底板破坏的影响;利用“专门电极电缆直流电法”现场观测采动过程中底板视电阻率变化,获得底板最大破坏深度。结果表明:8#煤底板破坏深度受顶板采空区和底板岩性组合的双重影响;顶板采空区的存在使8#煤开采时底板初始应力减小,应力集中程度减弱,回采过程中直接顶垮落步距减小,易形成“短砌体梁”结构,顶板周期来压伴随着底板裂隙的扩展;工作面底板实测最大破坏深度17.1m,相比于统计公式和塑性力学公式,预测值分别减小11.4%和7.8%,塑性力学公式相对适用性更好。

To study the influence of the upper coal goaf in close distance coal seams on the failure of the lower coal mining floor, taking the 8199 working face of Tashan Mine as an example, the failure depth of the working face floor is estimated through statistical formula and plastic mechanics formula; using bidirectional loading similarity simulation experiments to analyze the impact of roof with or without goaf on the floor failure; using the "specialized electrode cable direct current method" to observe the changes in the apparent resistivity of the floor during mining process on site, and obtain the maximum failure depth of the floor. The results show that the failure depth of the 8coal floor is influenced by the combination of roof goaf and floor lithological association; the existence of the roof goaf reduces the initial stress of the floor during the mining of the 8# coal, weakens the degree of stress concentration, and reduces the step distance of direct roof collapse during the stoping process, which easily forms a "short masonry beam" structure. The periodical weighting of the roof is accompanied by the expansion of cracks of the floor; the measured maximum failure depth of the working face floor is 17.1 m. Compared with statistical formula and plastic mechanics formula, the predicted values are reduced by 11.4% and 7.8%, respectively. The plastic mechanics formula has better applicability.