厚硬顶板悬顶致灾机理及切顶控制技术研究
Investigations on the disaster mechanism and roof cutting control technology of overhanging thick-hard roof
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摘要: 针对侧向厚硬悬顶下临空巷道围岩变形大、失稳风险高的问题,本文以大同马脊梁煤矿3810工作面运输巷为工程背景,调研了现场变形破坏特征;建立厚硬侧向悬顶力学模型,确定合理切顶位置理论值为内错煤柱3.98m,并对其影响因素进行分析。建立UDEC数值计算模型,反演分析了厚硬悬顶长度及切顶位置对煤柱垂直应力分布、破坏深度以及围岩变形破坏特征的影响规律,揭示了厚硬侧向悬顶致灾及切顶卸压控制机理。结合理论分析及模拟结果,提出了厚硬悬顶水压致裂切顶技术方案及其关键参数并成功应用于现场工程实践。现场试验结果表明:巷道两帮变形量最大为600mm,顶板下沉量最大为277mm;与未切顶区段的巷道变形相比分别减小39.6%(两帮)、31.8%(顶板),有效降低了巷道返修工程量,确保了煤炭安全高效生产。Abstract: In response to the problem of large deformation and high instability risk of surrounding rock in the gob-roadway under the lateral thick-hard overhanging roof, this article takes the headgate of the No. 3810 longwall face of Majiliang Coal Mine as the engineering background and investigates the field deformation and failure characteristics. A mechanical model for thick and hard lateral suspended roof was established to determine the reasonable cutting position, which is the distance of coal pillars within 3.98m. A UDEC numerical calculation model was established to invert and analyze the influence of the length and cutting position of the thick- hard overhanging roof on the vertical stress distribution, failure depth, and deformation and failure characteristics of the coal pillar and surrounding rock. The disaster caused by the thick - hard lateral overhanging roof and the pressure relief control mechanism of the roof cutting were revealed. Based on theoretical analysis and simulation results, a hydraulic fracturing for roof cutting technology scheme and its key parameters were proposed and successfully applied in on-site engineering practice. The results show that the maximum deformation of the two sides of the roadway is 600mm, and the maximum subsidence of the roof is 277mm; Compared with the deformation of the roadway in the uncut section, the deformation is reduced by 39.6% (for both sides) and 31.8% (for the roof), effectively reducing the amount of roadway repair work and ensuring safe and efficient coal production.
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