露天煤矿端帮遗煤开采顶板破断特征研究

Study on roof fracture characteristics of residual coal mining atend slope in open-pit coal mine

为安全高效回收露天煤矿端帮压煤,以内蒙古某露天煤矿开采条件为研究背景,采用理论分析和数值模拟方法,研究了综放工作面顶板破断移动规律。结果表明,工作面顶板条件适用于的三边固支一边简支薄板力学模型,随着工作面顶板悬露距离的增加,顶板应力分布发生变化,根据岩层破断判据,当悬露长度达到20 m时,应力σy在固支长边a/■位置应力峰值达到岩石抗拉强度,顶板于固支长边发生拉破坏。数值模拟结果显示,工作面开采至22 m时开始来压,且表现在工作面20~70 m,其他位置来压滞后。覆岩厚度较小处,地表位移差较大,达到54 mm,该位置应注意工作面顶板和边坡稳定防护。研究结果可为工作面来压预报提供理论依据,也可为相似条件工作面提供借鉴。

In order to safely and efficiently recover the end slope coal in open-pit coal mine,the mining conditions of an open-pit coal mine in Inner Mongolia are taken as the research background,the roof fracture and movement law of fully-mechanized working face was studied by theoretical analysis and numerical simulation.The research results show that roof condition of working face is suitable for mechanical model of the thin plate with three sides fixed and one side simply supported.With the increase of roof overhang distance of working face,the stress distribution of roof changes.According to rock stratum fracture criterion,when the overhang length reaches 20 m,the stressσy peak reaches the rock tensile strength at the position of a/5 on the long side of the fixed support,and the top plate undergoes tensile failure on the long side of the fixed support.The numerical simulation results show that the working face starts to pressure when the mining reaches 22 m,and the pressure appears in the range of 20~70 m of the working face,and the other position lag behind.When the thickness of overburden is small,the surface displacement difference is larger,reaching 54 mm.At this location,attention should be paid to stability protection of working face roof and slope.The research results can provide a theoretical basis for predicting pressure on the working face,and can also provide reference for working faces with similar conditions.