急倾斜煤层壁式开采覆岩移动机理及地表移动规律研究

发布时间：2019-04-20 17:05

【摘要】：煤层开采引起的岩层移动是一个复杂的过程，一般认为急倾斜煤层倾角大于45°，正是由于倾角大、地质结构复杂，所以急倾斜煤层开采引起的岩层移动以及地表变形规律更为复杂。煤层开采后，除顶板岩层出现变形移动外，开采煤层超过一定角度后煤层底板也会出现一定的破坏变形；对于存在水平基岩风化带或松散层的急倾斜煤层来说，地表变形规律受到两种结构的影响，更加难以预计地表变形。本文以江西青山矿地质资料为背景，通过理论分析、相似材料模拟实验、数值模拟计算相结合的方法对急倾斜煤层覆岩移动机理及地表变形规律进行了一些尝试性地研究，主要工作以及结论有以下几点：（1）根据急倾斜煤层开采岩层受力特点，分析岩层移动的规律，认为由于煤层倾角大，受力可以分解为沿法向和沿切向的作用力，煤层开采后顶板依次经历垮落-裂隙-弯曲以及沿层面的滑动; （2）采用基础力学的方法对煤层顶底板的受力变形情况进行理论分析。将顶底板岩层简化为“梁”，并认为“岩梁”受到横向力和轴向力，采用材料力学纵横弯曲理论以及弹性力学最小势能原理对岩层弯曲的挠度、滑移量进行推算；（3）根据急倾斜煤层开采后采空区垮落特征以及岩层受力情况，对覆岩以及地表变形规律进行分析，认为近地表水平基岩内存在非对称的应力拱，并且地表最大下沉值应在拱顶处；（4）通过相似模拟实验，对不同采厚、不同开采垂高的急倾斜煤层开采进行模拟，分析煤层开采后不同开采阶段顶板岩层不同的垮落变形形态，为更准确分析岩层移动规律提供实验依据；（5）在相似模拟实验中，对不同位置的测线下沉量和水平位移量进行分析，对不同层位的岩层移动变形有了系统的认识；（6）分析相似模拟实验中不同采厚和不同开采垂高的地表下沉曲线，并与岩层变形规律进行对比；（7）运用离散元数值模拟对不同开采厚度、开采垂高、开采倾角以及不同水平基岩厚度的急倾斜煤层开采进行数值模拟计算，并分析了覆岩位移与垂直应力规律，进而影响岩层移动的因素有了定性的了解；（8）通过对数值模拟计算结果的地表下沉曲线分析，并与相似模拟实验结论相对比，，得出了岩层移动与地表变形的规律之间内在关系。本文针对“煤层覆岩—水平基岩—地表”的移动规律，采用理论分析、相似模拟实验以及数值模拟计算的手段，分析了急倾斜煤层开采覆岩移动机理以及地表变形规律，为急倾斜煤层开采采场岩层控制以及地表变形预计提供了新的借鉴。
[Abstract]:The movement of strata caused by coal seam mining is a complex process. It is generally believed that the dip angle of steep inclined coal seam is greater than 45 掳, which is precisely due to the large dip angle and the complicated geological structure. Therefore, the law of rock movement and surface deformation caused by steep coal seam mining is more complicated. After coal seam mining, in addition to the deformation and movement of roof strata, there will also be some damage and deformation of coal seam floor after mining coal seam beyond a certain angle. For the steep coal seam with horizontal bedrock weathering zone or loose layer, the surface deformation law is affected by two kinds of structures, so it is more difficult to predict the surface deformation. In this paper, based on the geological data of Qingshan Mine in Jiangxi Province, the mechanism of overlying rock movement and the regularity of surface deformation in steep coal seam have been studied by means of theoretical analysis, similar material simulation experiment and numerical simulation calculation. The main work and conclusions are as follows: (1) according to the characteristics of stress in steep seam mining, the law of rock movement is analyzed, and it is considered that due to the large inclined angle of coal seam, the force can be decomposed into forces along normal direction and tangential direction, and the force can be divided into normal and tangential forces. After coal seam mining, the roof goes through caving, fissures-bending and sliding along the plane in turn; (2) the theoretical analysis of the stress and deformation of coal seam roof and floor is carried out by the method of foundation mechanics. The roof and floor rock stratum is simplified as "beam", and it is considered that "rock beam" is subjected to transverse force and axial force. The bending deflection and slip amount of rock stratum are calculated by the theory of longitudinal and transverse bending of material mechanics and the principle of minimum potential energy of elastic mechanics. (3) according to the collapse characteristics of goaf after steep inclined coal seam mining and the stress condition of strata, the law of overlying rock and surface deformation is analyzed, and it is concluded that there are asymmetric stress arches in horizontal bedrock near the surface. And the maximum subsidence value of the surface should be at the top of the arch; (4) through the similar simulation experiment, the steep inclined coal seam mining with different mining thickness and vertical height is simulated, and the different collapse and deformation patterns of roof strata in different mining stages after coal seam mining are analyzed. To provide experimental basis for more accurate analysis of strata movement law; (5) in the similar simulation experiment, the subsidence and horizontal displacement of measuring lines in different positions are analyzed, and the movement and deformation of strata in different strata are systematically understood. (6) analyze the surface subsidence curve of different mining thickness and vertical height in similar simulation experiment, and compare it with the deformation law of rock stratum; (7) numerical simulation of steep coal seam mining with different mining thickness, mining vertical height, mining dip angle and different horizontal bedrock thickness is carried out by using discrete element numerical simulation, and the law of displacement and vertical stress of overlying rock is analyzed. Then the factors that affect the movement of strata have a qualitative understanding; (8) by analyzing the surface subsidence curve of the numerical simulation results and comparing with the similar simulation experimental results, the inherent relationship between the rock movement and the surface deformation is obtained. In view of the movement rule of "coal seam overlying rock-horizontal bedrock-surface", this paper analyzes the mechanism of overlying rock movement and the law of surface deformation in steep inclined coal seam mining by means of theoretical analysis, similar simulation experiment and numerical simulation calculation. It provides a new reference for mining stope strata control and surface deformation prediction in steeply inclined coal seam.
【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】：TD325

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