Esterhuizen Gabriel S, Tulu I Berk, Gearhart Dave F, Dougherty Heather, Van Dyke Mark
National Institute for Occupational Safety and Health, Pittsburgh Mining Research Division, Pittsburgh, PA 15236, USA.
West Virginia University, Morgantown, WV 26506, USA.
Int J Min Sci Technol. 2021 Jan;31(1):103-110. doi: 10.1016/j.ijmst.2020.12.016.
Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted panel. The stress changes can result in significant deformation of the entries that may include roof sag, rib dilation, and floor heave. Mine operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall face. This paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support alternatives. The research included monitoring of ground and support interaction at several operating longwall mines in the U.S., analysis and calibration of numerical models that adequately represent the bedded rock mass, and observation of the support systems and their response to changes in stress. The models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic scenarios. The research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress changes. This information is then used to assess the ability of support systems to maintain the stability of the roof. The application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof fall. The method is shown to produce realistic estimates of gateroad entry stability and support performance, allowing alternative support systems to be assessed during the design and planning stage of longwall operations.
长壁开采的顺槽巷道会受到采空区周围载荷重新分布引起的水平和垂直应力变化的影响。应力变化可能导致巷道出现显著变形，包括顶板下沉、煤帮膨胀和底板隆起。煤矿经营者安装不同类型的支护来控制围岩响应，维持长壁工作面的安全通行和通风。本文介绍了近期的研究，旨在量化长壁开采引起的应力变化对围岩稳定性的影响，并利用这些信息评估支护方案。该研究包括对美国多个正在开采的长壁煤矿的围岩与支护相互作用进行监测，对能够充分代表层状岩体的数值模型进行分析和校准，以及观察支护系统及其对应力变化的响应。然后利用这些模型研究地质和应力条件对不同覆岩深度和地质情况的围岩变形及支护响应的影响。研究结果总结为两个回归方程，可用于估算长壁开采引起的应力变化导致的可能顶板变形和顶板屈服高度。然后利用这些信息评估支护系统维持顶板稳定性的能力。通过对一个经历了运输巷顶板冒落的正在开采的长壁煤矿的支护性能进行回顾性分析，展示了该方法的应用。结果表明，该方法能够对顺槽巷道的稳定性和支护性能做出实际估计，从而在长壁开采作业的设计和规划阶段对替代支护系统进行评估。
