User-friendly finite element design of main entries, barrier pillars,and bleeder entries

This contribution describes development and application of a user-friendly finite element program,UT3PC, to address three important problems in underground coal mine design:(1) safety of main entries,(2) barrier pillar size needed for entry protection, and(3) safety of bleeder entries during the advance of an adjacent longwall panel.While the finite element method is by far the most popular engineering design tool of the digital age, widespread use by the mining community has been impeded by the relatively high cost of and the need for lengthy specialized training in numerical methods.Implementation of UT3PC overcomes these impediments in three easy steps.First, a material properties file is prepared for the considered site.Next, mesh generation is automatic through an interactive process.A third and last step is simply execution of the program.Examples using data from several western coal mines illustrate the ease of using the application for analysis of main entries, barrier pillars, and bleeder entry safety.

上山保护煤柱应力传递规律解析

为研究煤层下行开采过程中上山保护煤柱应力传递规律,防治深部开采中煤柱支承压力向下传递形成应力集中引起的动力灾害,采用理论分析和数值模拟方法,基于弹性力学原理推导上山保护煤柱应力传递规律函数,并应用于某矿煤柱应力传递;运用FLAC3D数值模拟某矿1#煤层遗留煤柱对2#煤层巷道掘进的影响.研究结果表明:上山保护煤柱力学模型包括大煤柱和小煤柱2个部分,煤柱垂直应力传递具有扩散和衰减作用;2#煤层处于煤柱下方时,煤体应力为19.93~22.39 MPa,垂直应力增量峰值为3.13 MPa,高出原岩应力13.6%,增大了动力灾害发生的危险;煤柱对2#煤层影响范围为进煤柱前100m到出煤柱后100m.研究结论揭示了上山保护煤柱垂直应力传递规律,有助于防治由煤柱支承压力集中引起的动力灾害.

区域采动裂隙实测与演化模拟

为揭示唐山矿T2291面周边区域采动裂隙的演化规律,采用现场实测与离散元模拟方法,观测分析中硬顶板中离层成组渐次发展并集中形成的现象.根据拉、剪裂隙的形成机制,提出UDEC后处理的"两带"划分标准.研究结果表明:竖向贯通的BOUNDARY线表征冒落带、OPEN线表征裂隙带,可与实测高度相互印证;T2291周边10~30 m的隔离煤柱不能阻断周边采空区的瓦斯汇入,区域三维鞍形裂隙区的客观存在,是单孔巨量瓦斯抽放得以实现的重要机制,为中硬煤系地层中大间距布孔抽采瓦斯提供了成功范例.

巷-孔瞬变电磁探测技术在煤矿老空区防治中的应用

煤矿老空区水害具有突发性强、涌水量大、破坏性强等特点,是制约煤矿安全生产的重大隐患,且老空区开采历史久远,积水量大,图纸资料不全,具体位置很难准确掌握。常规瞬变电磁探测受外界因素干扰较多,准确率不高,而孔内瞬变电磁探测主要在钻孔内进行,干扰因素少,探测位置更接近目标,准确率较高。巷-孔瞬变电磁探测技术即上述2种方法综合探测技术,能够做到相互弥补,相互验证,有利于老空区范围的准确圈定。

上层煤柱下综放沿空回采巷道矿压规律研究

为揭示上层残留煤柱下综放沿空回采巷道矿压显现规律,有效控制围岩变形,根据阳泉一矿8902综放面地质与开采条件,结合现场沿空回采巷道矿压观测结果,应用FLAC3D数值模拟计算分析回采巷道塑性区发育及应力分布情况.研究表明,综放回采巷道在上层残留煤柱影响与本层煤回采引起的应力重新分布耦合作用下,回风巷两帮及顶底移近量高达1985,1877mm,局部断面不足2m2,严重制约了工作面安全高效生产,采取合理布置回采巷道及减小区段煤柱宽度等措施可有效维护巷道.