“见方效应”与“应力击穿效应”联动致灾机理及防治技术研究

Study on the mechanism and prevention technology of “square position” and “stress breakdown effect” inducing rockburst

为保障工作面推进至接近见方位置时安全回采。以郓城煤矿1301工作面为工程背景,采用现场监测、数值模拟和理论分析的方法,研究了深井、厚表土、厚基岩特厚煤层工作面推进至见方位置时的致灾机理与安全开采技术。得到如下结论:深井、厚表土、厚基岩、特厚煤层工作面仍存在"见方效应",见方时,前方煤体集中应力和集中应力系数达到最大;对厚表土起承载作用的岩层跨度达到极限破坏长度,厚表土载荷将岩层击穿,称为厚表土的应力击穿效应,此时厚表土由静载转化为动载加载至工作面前方煤体,"应力击穿效应"为冲击地压发生的诱发因素;数值模拟结果表明,"见方效应"与"应力击穿效应"相互叠加致工作面前方煤体应力集中的范围在70 m左右,微震监测和应力在线实时监测验证了理论计算的正确性。

In order to ensure the production safety when the gob of the longwall panel becomes a square shape, taking the longwall panel 1301 of Yuncheng coal mine as the engineering background, buy using the in-situ monitoring, numerical simulation and theoretical analysis methods, the disaster-causing mechanism as well as the safety techniques are analyzed for the deep mines with thick topsoil, bed rock and coal seam. Results show that, at the ＂square position＂ stage, the concentrated stress and the concentrated stress factor in front of the working face reached the maximum value. The span of the strata that bear the thick topsoil reaches the failure limit resulting the breakdown of strata by the stress of the thick topsoil. This is so called ＂stress breakdown effect＂ of the topsoil. At this time, the static loading of the thick topsoil is transformed to the dynamic loading which applies to the coal body ahead of the working face. The ＂stress breakdown effect＂ is the inducing factor of the rockburst. Numerical simulation results demonstrate that the ＂square effect＂ and the ＂stress breakdown effect＂ overlapped with each other, causing the range of the stress concentration in front of the working face to be around 70 m. Microseismic monitoring and stress online real-time monitoring verify the accuracy of theoretical calculations.