Geotechnical risk management to prevent coal outburst in room-and-pillar mining

A coal outburst is a severe safety hazard in room-and-pillar mining under deep cover. It is more likely to occur during pillar retreating. Multi-seam mining dramatically increases the risk of coal outburst within the influence zones created by remnant pillars and gob-solid boundaries. Though coal outburst is generally associated with heavy loading of coal pillars,its occurrence is difficult to predict. Risk management provides a proactive tool to minimize coal outburst in room-and-pillar mining under deep cover. Risk assessment is the first step in identifying and quantifying outburst risk factors. The primary risk factors for coal outburst are overburden depth,roof and floor strength,geological anomalies,mining type,multi-seam mining,and panel width. A risk assessment chart can be used to proactively screen out mining sections with high risk of coal outburst for further analysis. Gob-solid boundaries and remnant pillars are critical factors in evaluation of the coal outburst risk of multi-seam mining. Risk identification,risk assessment,geologic influence mapping,geotechnical evaluation,risk analysis,risk mitigation,and monitoring are essential elements of coal outburst risk management process. Training is an integral part of risk management for risk identification and communication between all the stakeholders including management,technical and safety personnel,and miners.

基于双强度折减幅值加权法的公路边坡稳定性研究

基于双强度折减法(DRM)的研究现状,提出了两个需要进一步深化的问题,一是DRM在多岩土层边坡的应用性如何,二是寻找一种准确且方便快捷的最终边坡稳定系数的确定方法。据此提出了折减幅值加权的双强度折减法,以内蒙古某高等级公路多岩土层深挖路堑高边坡为研究对象进行了研究分析。首先,阐明了双强度折减法在实际工程中的研究思路,推导了DRM边坡最终稳定系数的计算模型。其次,以K2+550-K3+150挖方段典型高边坡为例进行双强度折减法分析,叙述了双强度折减幅值加权法的实现过程,并与极限平衡法以及常用的3种双强度折减法模型计算结果进行了对比。为进一步验证方法的普遍适用性及准确性,采用了澳大利亚ACADS协会的均质边坡算例,采用多种方法对3组不同抗剪强度参数下边坡的稳定性计算结果进行了对比。结果表明:边坡最终稳定系数为1.281,与极限平衡法的计算结果相差2.18%,其他双强度折减法最终边坡稳定系数结果均偏大;折减幅值加权的强度折减法每次计算结果均与实际情况相近,其他双强度折减法确定的最终边坡稳定系数计算结果较离散;折减幅值加权的双强度折减法计算结果更符合实际工程,完全可以运用到实际边坡分析中,并且除稳定系数外还有剪应变增量及位移等综合判据,具有普遍适用性和较高的准确性。