软岩工作面开采引起上覆岩层移动变形规律研究

发布时间：2019-02-14 18:38

【摘要】：保护层开采及卸压瓦斯抽采是目前首选的区域性瓦斯治理措施,随着保护层的开采,被保护煤层的应力-应变状态和瓦斯应力动力状态会发生改变,煤层中的弹性势能被释放出来,裂隙的发育提高了煤层的透气性,被保护煤层内的瓦斯流动性变大,大量的瓦斯解吸出来,从而达到了卸压的作用,配合合理的抽采瓦斯措施,可以减小煤层内的瓦斯含量和内能,达到预防煤与瓦斯突出的目的。在工作面推进过程中,采场围岩原始的应力平衡被打破,上覆各岩层由于自重和其他岩体的应力作用而失去平衡,从而发生移动和变形。离工作面最近的岩层产生的移动变形最大,岩体的破碎度也最大,在采空区附近形成冒落区;在冒落区的上部岩体内裂隙得到发育,纵横交错的裂隙网组成岩体内的裂隙区;裂隙区上部的岩体保持了较好的稳定性,呈规则状下沉。由于上覆岩层内可能存在地下水、待采煤层、地表有各种建筑物等因素,是否能准确的判断出采场推进后覆岩各岩层的移动变形情况和可能的影响范围,对实际生产和制定安全措施具有非常大的指导意义。在没有合适的煤层作为保护层开采的情况下可以选择相对合理的岩石工作面作为保护层进行开采。本文结合芦岭矿软岩工作面开采的实际生产情况,运用相似模拟实验的方法对软岩工作面开采后引起的覆岩移动变形的情况进行探究,测量不同推进距离条件下采空区中部位置上覆岩层在垂直方向上的应力变化和位移变化情况,对实验得到的数据进行分析整理,结合实验结果对覆岩移动变形的"三带"范围进行预判,探讨软岩工作面作为上部煤层的保护层开采起到的作用效果。为了对覆岩的移动变形情况在整体上加以了解,本文结合数值模拟的方法对软岩工作面开采后可能引起的覆岩移动变形的因素进行定量分析,分析在不同推进距离条件下在采场工作面走向和倾向方向上采空区中部位置上部岩层的应力大小和位移情况,利用岩体受到的主应力作用的大小和性质来判断"三带"的范围,以此来检验软岩工作面作为上部煤层保护层开采的作用效果。利用两种实验方法得到的模拟结果对实际生产有很好的参考意义。
[Abstract]:Protection layer mining and pressure-relief gas drainage are the preferred regional gas control measures at present. With the mining of the protective layer, the stress-strain state and the gas stress dynamic state of the protected coal seam will change. The elastic potential energy in the coal seam is released, the development of the fissure improves the permeability of the coal seam, the gas fluidity in the protected coal seam becomes larger, a large amount of gas desorbs out, thus the function of releasing the pressure is achieved, and the reasonable gas drainage measures are cooperated. The gas content and internal energy in coal seam can be reduced, and the purpose of preventing coal and gas outburst can be achieved. During the working face advance, the original stress balance of surrounding rock in stope is broken, and the overburden strata lose balance because of self-weight and stress action of other rock mass, thus the movement and deformation occur. The rock strata closest to the face produce the largest movement deformation and the largest degree of rock mass fragmentation, forming caving areas near the goaf, the cracks in the upper rock body of the caving area are developed, and the crisscross fissure network forms the fracture area in the rock body. The rock mass in the upper part of the fissure area keeps a good stability, and the subsidence is regular. Because there may be underground water in overlying strata, coal seams to be mined, various buildings on the surface, etc., can accurately judge the movement and deformation of overburden strata after stope pushing and its possible influence range, To the actual production and the formulation of safety measures have a great significance. In the absence of a suitable coal seam as a protective layer, a relatively reasonable rock face can be selected for mining. Combined with the actual production situation of soft rock mining in Luling Mine, this paper uses the method of similar simulation experiment to study the deformation of overlying rock caused by soft rock mining. The stress and displacement changes of overlying strata in the middle of the goaf are measured under different propulsive distances, and the experimental data are analyzed and sorted out. Based on the experimental results, the range of "three zones" of overburden movement and deformation is forecasted, and the effect of soft rock working face as the protective layer of upper coal seam is discussed. In order to understand the movement and deformation of overburden on the whole, this paper, combined with the method of numerical simulation, makes quantitative analysis of the factors which may cause the movement and deformation of overburden after mining in soft rock face. This paper analyzes the stress magnitude and displacement of the upper strata in the middle part of the goaf under the conditions of different propulsive distances, and judges the range of the "three zones" by using the magnitude and nature of the main stress acting on the rock mass. The effect of soft rock working face as the protective layer of upper coal seam is tested. The simulation results obtained by the two experimental methods are very useful for practical production.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD325

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