采空区及煤柱下不同位置巷道稳定性控制研究

发布时间：2018-07-28 06:54

【摘要】：在近距离煤层开采过程中,当上层煤回采完毕及顶板垮落后,上层煤开采过程中所留设的煤柱会在煤层底板产生应力集中,且底板的应力分布规律发生变化,直接影响到下部煤层顶板的完整性。下层煤在开采过程中,回采巷道围岩压力大、顶板稳定性差,导致巷道变形破坏严重,支护困难。因此,针对近距离煤层中下层煤的应力分布规律、下层煤不同位置巷道的围岩压力、破坏特征及稳定性控制的研究具有理论和应用意义。本文以嘉乐泉煤矿8#、9#近距离煤层开采为研究背景,结合理论分析、数值模拟及工程应用等方法,对近距离煤层的矿压分布规律、下层煤不同位置巷道的变形破坏特征和巷道围岩稳定性控制进行研究,主要研究结论如下:(1)利用滑移线场理论对上部煤层开采对其下部岩层所产生的扰动影响规律进行了分析,得到上层煤开采对下部岩层的最大破坏深度计算方法。结合嘉乐泉煤矿实际地质条件,计算、分析得出该矿采空区下不同深度岩层应力分布规律。结果显示:下层煤受上覆煤层开采扰动影响最大的是垂直应力;煤柱及其两侧5m范围内的下部岩层的垂直应力大于原岩应力,煤柱中心处为最大值,煤柱两侧5m以外的下部岩层垂直应力小于原岩应力。(2)随着煤柱下的岩层与上层煤柱间距的缩小,岩层的垂直应力增大明显,最大达到16MPa,是原岩应力的2.56倍。巷道开挖后,围岩水平应力和剪切应力变化较小,但垂直应力明显升高,增大1.4~1.7倍,巷道围岩应力集中现象明显;采空区下巷道围岩最大垂直应力为9MPa,煤柱下巷道围岩最大垂直应力达到25MPa。(3)下层煤中位于采空区下方的巷道受上覆采空区卸压影响,巷道两帮和两肩处所受围岩压力减缓,巷道围岩剪切破坏范围较小,巷道整体稳定性较好。但位于煤柱下的下层煤巷道开挖后,受煤柱应力集中影响,巷道围岩剪切破坏范围明显增大,巷道变形破坏严重,尤其巷道两肩围岩剪切裂隙发育,顶板下沉量较大。(4)在围岩分布规律和巷道稳定性分析的基础上,对嘉乐泉煤矿煤柱下巷道支护参数进行了优化。工程应用与监测结果显示,巷道顶底板及两帮变形量都有明显减小,锚索受力范围合理,巷道剪切破坏区域减小,表明巷道优化方案取得良好支护效果,保证了巷道在使用期间的安全和稳定。
[Abstract]:In the process of close distance coal seam mining, when the upper coal mining is finished and the roof collapses behind, the coal pillars left in the upper coal mining process will produce stress concentration in the coal seam floor, and the stress distribution law of the floor will change. It directly affects the integrity of the lower coal seam roof. In the mining process of the lower coal, the surrounding rock pressure of the mining roadway is high and the roof stability is poor, which leads to the serious deformation and destruction of the roadway and the difficulty of supporting. Therefore, it is of theoretical and practical significance to study the stress distribution law of the coal in the middle and lower coal layers, the surrounding rock pressure, failure characteristics and stability control of the roadway in different positions of the lower coal seam. In this paper, based on the research background of Jialequan Coal Mine No. 8 #yun9# coal seam mining, combined with theoretical analysis, numerical simulation and engineering application, the distribution law of coal pressure in the near distance coal seam is studied. The deformation and failure characteristics of roadway in different positions of lower coal and the stability control of roadway surrounding rock are studied. The main conclusions are as follows: (1) the influence law of disturbance caused by mining of upper coal seam on rock layer under coal seam is analyzed by using slip line field theory. The method of calculating the maximum damage depth of upper coal mining to the lower strata is obtained. Combined with the actual geological conditions of Jialequan Coal Mine, the stress distribution law of different depths in the goaf is obtained by calculation. The results show that the vertical stress of the lower coal is the most affected by the mining disturbance of the overlying coal seam, the vertical stress of the lower strata within 5 m of the pillar and its two sides is greater than that of the original rock, and the maximum value is at the center of the coal pillar. The vertical stress of the lower strata beyond 5m on both sides of the coal pillar is smaller than that of the original rock. (2) with the reduction of the distance between the strata under the pillar and the upper coal pillar, the vertical stress of the strata increases obviously, reaching the maximum of 16 MPA, which is 2.56 times of the original rock stress. After excavation, the horizontal stress and shear stress of the surrounding rock change little, but the vertical stress increases obviously, and increases by 1.4 to 1.7 times, and the stress concentration in the surrounding rock of the roadway is obvious. The maximum vertical stress of roadway surrounding rock under goaf is 9 MPA, and the maximum vertical stress of surrounding rock under coal pillar is up to 25 MPA. (3) the roadway below the goaf in the lower coal is affected by the pressure relief of overlying goaf, and the pressure of surrounding rock at two sides and two shoulders of roadway is reduced. The shear failure range of surrounding rock is small and the overall stability of roadway is better. However, after the lower coal roadway is excavated under the coal pillar, the shear failure range of the surrounding rock of the roadway increases obviously, especially the shear fracture of the surrounding rock on the two shoulders of the roadway is developed, especially the shear fracture of the surrounding rock on the two shoulders of the roadway. (4) based on the analysis of the distribution of surrounding rock and the stability of roadway, the parameters of roadway support under coal pillar in Jialequan coal mine are optimized. The engineering application and monitoring results show that the deformation of the roof and floor and the two sides of the roadway are obviously reduced, the stress range of anchor cable is reasonable, and the shear failure area of roadway is reduced, which indicates that the optimized roadway scheme has achieved good support effect. It ensures the safety and stability of roadway during use.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD322.4;TD353

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