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倾斜煤层厚硬顶板切顶留巷关键参数优化研究

Study on optimization of key parameters of thick hard roof cutting and retaining roadway in inclined coal seam

  • 摘要: 为解决回采巷道倾斜厚硬顶板应力集中问题,降低顶板覆岩突然垮落的冲击扰动风险及提高倾斜厚硬顶板切顶留巷围岩控制效果,以长城六矿1301N运输巷切顶留巷为工程背景,综合采用理论分析、数值模拟及现场监测的研究方法开展倾斜煤层厚硬顶板切顶留巷关键参数优化研究。首先,基于岩石碎胀系数、砌体梁理论及现场地质资料,推导计算了1301N运输巷切顶高度和切顶角度的理论最小值。其次,为进一步验证并优化理论推导结果,利用PFC2D数值软件建立了1301N工作面切顶留巷模型,采用控制变量法分析了不同切顶高度和切顶角度下留巷顶板应力、位移及组构张量响应特征。分析结果表明:切顶高度与卸压效果之间存在底数大于1的对数增长关系,即随着切顶高度增加,卸压效果逐渐增强但其增长幅度逐渐减小;切顶角度与卸压效果之间存在“S”型增长关系,即随着切顶高度增加,卸压效果先增强后减弱。卸压参数与卸压效果之间的变化规律揭示了切顶高度选择存在最适值,切顶角度选择存在最优解。综合理论分析、经济收益及数值模拟结果,确定长城六矿1301N运输巷倾斜厚硬顶板切顶留巷过程中最适切顶高度为13 m,最优切顶角度为10°。现场监测获得该切顶参数下围岩控制效果较好,留巷围岩变形量较小,可有效满足下一工作面开采需求,验证了优化切顶参数的有效性,为类似地质条件切顶留巷参数的选取提供理论依据和实践参考。

     

    Abstract: To address stress concentration in mining roadways, particularly in the inclined, thick, and hard roof, and lessen the impact of sudden overlying strata collapse, a comprehensive study was conducted on the 1301N transport roadway in No.6 Great Wall Mine. The research utilized various methods such as theoretical analysis, numerical simulation, and field monitoring to optimize the key parameters of roof cutting and roadway retaining, leading to improved control of the surrounding rock and reduced risk of impact disturbance. Firstly, based on field geological data, the theoretical minimum roof-cutting height and angle of the 1301N transportation gateway were calculated using the coefficient of rock crushing and swelling and masonry beam theory. Furthermore, in order to confirm and enhance the accuracy of the theoretical findings, we utilized PFC2D numerical software to create a model of the roof-cutting retaining roadway situated in the No.1301N working face. By employing the control variable approach, we studied the response characteristics of roof stress, displacement, and surrounding rock fabric tensor of the retaining roadway at various roof-cutting heights and angles. The analysis results indicate a logarithmic relationship between cutting height and pressure relief effect. The effect increases with height, but growth amplitude decreases. There is an “S” growth relationship between the roof-cutting angle and the pressure relief effect. The pressure relief effect first increases and then decreases with the increase of the roof-cutting height. The change law between pressure relief parameters and pressure relief effect reveals that there is an optimal value for the selection of the roof-cutting height and an optimal solution for the selection of the roof-cutting angle. Based on the results of theoretical analysis and numerical simulation, it is determined that the most suitable roof-cutting height is 13 m, and the optimal roof-cutting angle is 10°. The field monitoring shows that the control effect of the surrounding rock under the roof-cutting parameters is good, and the deformation of the surrounding rock of the retaining roadway is small. It can effectively meet the mining demand of the next working face and verifies the effectiveness of optimizing the roof-cutting parameters. This provides a theoretical basis and practical reference for the selection of the parameters of roof cutting and retaining roadway under similar geological conditions.

     

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