倾斜厚煤层托顶煤掘进巷冲击地压机制与防冲布巷优化研究
Study on rockburst mechanism and layout optimization of top-coal roadway in the inclined thick coal seam
-
摘要: 为探究倾斜厚煤层掘进巷冲击地压机制及其有效的防治优化措施, 以新疆某煤矿(4–5)06W胶带巷掘进发生顶板型冲击地压为背景, 运用现场勘察、室内实验、力学建模及数值模拟等方法开展了研究, 总结了倾斜厚煤层托顶实体煤掘进巷冲击地压显现特征, 将冲击巷道破坏范围划分闭合区、严重破坏区及严重变形区, 通过现场勘察确定了巷道顶煤是冲击主体, 分析了煤层倾角、厚度及巷道煤岩组合对冲击地压发生的影响特征, 数值反演了工程背景下的冲击动力现象, 探讨了冲击地压发生的力学机制, 并提出巷道继续掘进防冲优化布置及解危卸压方案。研究结果表明: (1)随煤层倾角的增大, 正应力持续增大, 但变化范围较小; 顶板承受的切应力分为减小、缓慢增加和急速增加3个阶段; 计算得出工程背景下半煤岩巷道掘进积聚的能量大于煤层巷道; (2)倾斜厚煤层托顶实体煤巷道掘进冲击机制包括3方面, ①煤层倾角引发的顶板应力非均衡分布, ②锚索过长导致不能充分发挥其悬吊组合作用, 锚固效果较差, ③倾斜下滑力与原水平应力共同作用易诱发巷道顶板煤体离层冒落; (3)提出了巷道继续掘进防冲优化方案, 通过微震监测得出煤岩体积聚的能量由剧烈释放转为高频低能释放, 巷道掘进冲击危险性显著降低, 实现了(4–5)06W工作面剩余巷道的安全掘进。Abstract: To investigate rockburst mechanism and optimize prevention measure for roadway excavated in inclined thick coal seams, the roof-type rockburst during the development of the (4–5)06W belt roadway in a Xinjiang coal mine was taken as the engineering background. The characteristics of rockburst manifestations in inclined thick coal seams with top-coal roadways were systematically analyzed with field investigation, laboratory experiment, mechanical modeling and numerical simulation. The failure zones of impacted roadways were categorized into closure areas, severe damage areas and critical deformation areas. Field investigation identified the roof coal as the primary impact carrier. Roles of key influencing factors including coal seam dip angle, thickness, and coal-rock combinations in rockburst initiation were analyzed. Numerical simulation was used to reproduce the dynamic impact phenomena under engineering conditions, followed by a mechanistic analysis of rockburst mechanism. Optimization strategies for anti-impact roadway layout and hazard mitigation measures during excavation were proposed. It is found that normal stress increases slightly with coal seam dip angle, while roof shear stress undergoes three phases: reduction, gradual growth and rapid escalation. Energy accumulation in semi-coal-rock roadways exceeds that of roadways in pure coal seams under identical conditions. Three critical mechanisms governing rockburst in inclined thick coal seams were identified: dip-induced asymmetric stress distribution in roof strata; compromised anchoring efficacy due to excessive cable length, hindering composite suspension effects; synergistic action of inclined sliding forces and horizontal stresses promoting roof coal delamination and collapse. Microseismic transition from intense energy release to high-frequency/low-energy dissipation was observed after prevention measure optimization. The optimized scheme significantly reduced rockburst risks, enabling safe drivage of the remaining (4–5)06W roadway.