采空区煤壁下矿压分布规律及巷道稳定性控制研究

发布时间：2018-08-15 16:39

【摘要】：近距离煤层下行开采过程中，下层煤中矿压分布规律受到上层煤生产工作影响而发生改变，其中巷道布置方式与稳定性控制一直是困扰近距离煤层下层煤生产工作的难题之一。因此根据近距离煤层中下层煤中应力分布规律，深入研究其不同位置巷道围岩破坏特征与稳定支护对于有近距离煤层赋存的矿井高产高效生产具有重要意义。本文以炉峪口煤矿近距离煤层为研究对象，综合运用理论分析、数值模拟、工程监测等研究方法，在分析近距离煤层中受上覆采空区煤壁影响下层煤应力场分布规律的基础上，对下层煤中不同位置巷道破坏特征及稳定性控制进行了深入的研究，结果表明：（1）受上覆煤层采空区支承压力影响，下层煤应力场主要表现为垂直应力的变化，理论计算结果表明下层煤采空区下方上覆煤柱支承压力传递影响区域之外为垂直应力降低区，采空区煤壁正下方偏向采空区4m到煤柱下方25m为垂直应力升高区，垂直应力升高区内垂直应力可达原岩应力2倍左右。（2）下层煤应力分布受上层煤采高及煤层群埋深影响较小，受上层煤顶板岩性与煤层间距影响较大。具体表现为上层煤顶板坚固时，煤柱下方垂直应力升高明显增大，同时采空区下方垂直应力明显减小，随着两层煤间距的减小下层煤中应力峰值呈非线性急剧增大。（3）由于采空区的释压作用，位于采空区下的巷道围岩中垂直应力较小，，塑性区分布范围主要集中在顶底板岩层中，且分布区域较小，巷道变形量也较小；受煤柱传递支承压力的影响，位于上覆煤柱下的巷道两帮及两肩受到急剧升高垂直应力的影响，围岩发生大范围的剪切破坏，巷道变形量大。（4）下层煤巷道布置在上覆煤层采空区下方易于支护，布置在上覆煤柱下方支护难度较大，在工程实际中，最好将下层煤中的巷道布置在上覆煤层采空区下方并尽量避免将巷道布置在上覆煤柱下方，以减小巷道支护工作量。（5）煤柱下巷道在重视顶板支护的同时需加强对巷道两帮与两肩围岩控制，常规支护方案不能满足巷道稳定性要求，优化支护方案将巷道断面改为直墙半圆拱形断面，增大巷道锚杆索直径并提高预紧力，将锚索向两肩塑性屈服区域中倾斜布置，能够改善巷道两肩角处围岩受力状态，提高剪切破坏区域内围岩强度，增强巷道抗压能力，发挥支护体系作用及围岩的自承能力，保证巷道稳定性。
[Abstract]:In the process of downgoing mining of coal seam in close distance, the distribution law of mine pressure in the lower coal seam is affected by the production work of the upper coal, among which, the layout of roadway and the control of stability have been one of the difficult problems puzzling the production of coal in the lower coal layer of the near distance coal seam. Therefore, according to the stress distribution in the middle and lower coal seam, it is of great significance to study the failure characteristics of surrounding rock and the stability support of roadway in different positions for the high yield and high efficiency production of the coal mine with the occurrence of the close distance coal seam. In this paper, the close coal seam of Liuyukou coal mine is taken as the research object, and the distribution of the stress field of the lower coal is analyzed based on the theoretical analysis, numerical simulation, engineering monitoring and so on, on the basis of the analysis of the distribution law of the lower coal stress field under the influence of the coal wall of the overlying goaf in the near distance coal seam. The failure characteristics and stability control of roadway at different positions in the lower coal are studied in depth. The results show that: (1) the stress field of the lower coal is mainly the change of vertical stress due to the influence of the supporting pressure in the goaf of the overlying coal seam. The theoretical calculation results show that the vertical stress reduction area is outside the influence area of the supporting pressure transfer of the overlying coal pillar under the lower coal goaf, and the vertical stress rising area is located in the coal wall of the goaf directly below the goaf from 4 m below the goaf to 25 m below the pillar. In the area of vertical stress rise, the vertical stress can be about 2 times that of the original rock stress. (2) the distribution of the lower coal stress is less affected by the mining height of the upper coal and the buried depth of the coal seam group, but by the upper coal roof lithology and the coal seam spacing. When the upper coal roof is strong, the vertical stress under the coal pillar increases obviously, and the vertical stress under the goaf decreases obviously. With the decrease of the distance between two coal layers, the peak value of stress in the lower coal increases dramatically. (3) due to the pressure release of goaf, the vertical stress in the surrounding rock of roadway under goaf is smaller. The distribution range of plastic zone is mainly concentrated in the rock strata of roof and floor, and the distribution area is smaller, and the deformation of roadway is also small, which is affected by the bearing pressure of coal pillar, The two sides and shoulders of the roadway located under the overlying coal pillar are affected by the sharp increase of vertical stress, the surrounding rock is shearing in a wide range, and the deformation of the roadway is large. (4) the lower coal roadway is easy to be supported under the goaf of the overlying coal seam. It is difficult to arrange the support under the overlying coal pillar. In engineering practice, it is better to arrange the roadway in the lower coal seam under the goaf of the overlying coal seam and to avoid placing the roadway under the overlying coal pillar as far as possible. In order to reduce the workload of roadway support, (5) the roadway under coal pillar should pay more attention to roof support and strengthen the control of surrounding rock between two sides and two shoulders of roadway, and the conventional support scheme can not meet the requirement of roadway stability. The optimized support scheme can change the section of roadway into a semi-circular arch section of straight wall, increase the diameter of anchor cable and increase the pretightening force of roadway, and inclined the anchor cable to the plastic yield area of two shoulders, which can improve the stress state of surrounding rock at the corner of both shoulders of roadway. In order to ensure the stability of roadway, the strength of surrounding rock in the area of shear failure is improved, the ability of roadway to resist pressure is enhanced, the function of supporting system and the self-supporting ability of surrounding rock are brought into play.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD353

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