针对厚煤层综放沿空留巷时常出现底鼓的问题,以古城煤矿N2301巷为工程背景,采用现场调研、理论分析和数值模拟相结合的方法对巷道底鼓发生机理及其控制技术进行研究.现场调研发现,巷道呈现出明显的挤压流动性底鼓特征,构建深部高应力巷道底鼓力学模型,结合理论分析底鼓发生的机理.研究结果表明,巷道应力集中程度越高,巷道底板破坏深度越大.根据现场情况提出采用注浆加固的方法治理底鼓,运用COMSOL数值模拟软件研究了不同注浆参数条件下底板浆液压力分布范围,确定了 N2301巷道的注浆压力3 MPa、注浆时间6 min和注浆锚索间排距1 000 mm x 1 000 mm.工程应用表明,巷道最大底鼓量为15 mm,围岩深部6 m处最大离层值为23 mm.优化后的注浆参数在古城煤矿N2301巷超前支护中进行了工程应用,取得了良好的工程效果,研究成果对类似条件下巷道底鼓治理和注浆参数设计具有重要的参考价值.
Research on mechanism of floor heave occurrence and its control technology in thick coal seam comprehensive gob-side entry retaining
To address the problem of floor heave often occurs in the gob-side entry retaining of fully-mechanized caving in thick coal seams,this paper took the N2301 roadway of Gucheng Coal Mine as the engineering background and used a combination of field re-search,theoretical analysis and numerical simulation to study the mechanism of the occurrence of floor heave and its control technology.Field investigation found that the roadway exhibited obvious characteristics of squeeze flow and floor heave.A deep high stress roadway floor heave mechanical model was constructed,and the mechanism of floor heave occurrence was analyzed in combination with theory.The results showed that the higher the degree of stress concentration in the roadway,the greater the depth of damage to the roadway floor.According to the field situation,the method of grouting reinforcement was proposed to control the floor heave,and COMSOL numer-ical simulation software was used to study the range of bottom slurry pressure distribution under different grouting parameters,and the grouting pressure of 3 MPa,grouting time of 6 min and the row distance between anchor cables of 1000mm × 1000mm were determined for N2301 roadway.Engineering applications showed that the maximum floor heave of the roadway was 15 mm,and the maximum separa-tion value at a depth of 6 m in the surrounding rock was 23 mm.The optimized grouting parameters were applied in the advance support-ing of N2301 roadway in Gucheng Coal Mine,and good engineering results were achieved,and the research results have important refer-ence value for the management of bottom drum and design of grouting parameters in similar conditions.
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