近浅埋煤层条带开采地表沉陷主控因素研究及沉陷预计方法

发布时间：2018-02-28 04:30

本文关键词： 近浅埋煤层条带开采正交实验主控因素沉陷预计　出处：《太原理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：目前，地表沉陷预计方法主要是以概率积分法为代表的各类经验预测法，此类方法基于实测资料得出经验公式，但不涉及对采场上覆岩层移动规律的研究，且往往不适用于不充分采动条件下地表沉陷预计。由于近浅埋煤层距地表较近，地表更容易受到开采活动的影响，因此，本文通过正交实验、数值模拟、理论分析等手段，针对近浅埋煤层条带开采这种极不充分采动条件，分析研究了地表沉陷的主控因素及主控因素对上覆岩层移动规律的影响，并在此基础上建立了覆岩关键层的力学模型，将覆岩移动与地表沉陷相联系，提出了近浅埋煤层条带开采条件下的地表沉陷预计方法。具体研究内容及获得的主要结论如下： 1）本文对近浅埋煤层条带开采这一概念进行了限定：近浅埋煤层是指埋深不超过200m，基载比1~5，上覆岩层中存在一到两组关键层的煤层，条带开采是指采出宽度不足以使上覆岩层达到充分采动状态，且保留条带有足够宽度和稳定性来支撑上覆岩层的开采方法。 2）针对覆岩移动及地表沉陷的影响因素繁多这一特点，对这些因素分组进行正交实验：第一组实验的因素为主关键层的物理力学参数；第二组实验保留第一组实验中的显著因素，并考虑了亚关键层与表土层的影响；第三组实验则考虑了关键层层位，非关键层岩层的分层厚度及物理力学性质；第四组实验针对煤层的物理力学性质进行；第五组实验保留了第四组实验的显著因素，又考虑了开采尺寸与煤层附近岩层物理力学性质的影响。 3）对正交实验得出的显著因素进行单因素实验，分析这些因素对上覆岩层移动规律的影响，既对正交实验的结果进行了验证，又进一步确定了条带开采地表沉陷的主控因素。最终确定的近浅埋煤层条带开采主控因素有：开采尺寸（采宽、留宽、采高），亚关键层厚度；对地表下沉有一定影响，，但影响弱于主控因素的因素有：主关键层厚度，亚关键层弹性模量与泊松比，层间岩层的泊松比与内摩擦角，煤柱的粘聚力、内摩擦角与泊松比。 4）基于近浅埋煤层条带开采的覆层移动特征，建立了亚关键层与主关键层的力学模型，并根据两者下沉量之间的关系，通过亚关键层的挠曲线求出了主关键层的挠曲线；对亚关键层进行了力学分析，验证所建立力学模型对主控因素的响应是否符合上覆岩层的移动规律，结果显示基本吻合；最终通过主关键层的挠曲线得到地表下沉曲线，并提出了近浅埋煤层条件下的地表沉陷预计方法。
[Abstract]:At present, the prediction methods of surface subsidence are mainly based on probabilistic integration method, which is based on the measured data to obtain empirical formulas, but does not involve the study of overlying strata movement law. And it is often not suitable for the prediction of surface subsidence under the condition of insufficient mining. Because the near shallow coal seam is close to the ground surface, the surface is more vulnerable to the influence of mining activities. Therefore, this paper, by means of orthogonal experiment, numerical simulation and theoretical analysis, aims at the extremely inadequate mining conditions of strip mining in near shallow coal seam. This paper analyzes and studies the main controlling factors of surface subsidence and the influence of main controlling factors on the law of overlying strata movement. On the basis of this, a mechanical model of the key strata of overlying rock is established, which connects the overlying rock movement with the surface subsidence. The prediction method of surface subsidence under the condition of strip mining of near-shallow coal seam is put forward. The concrete research contents and the main conclusions obtained are as follows:. 1) in this paper, the concept of strip mining of near-shallow coal seam is limited: the near shallow coal seam is a coal seam with a buried depth of less than 200 m, a ratio of 1 to 5, and one or two groups of key layers in the overlying strata. Strip mining is a mining method in which the mining width is not enough to make the overlying strata fully mining and the strip has sufficient width and stability to support the overlying strata. 2) in view of the fact that there are many factors affecting overburden movement and surface subsidence, orthogonal experiments are carried out on these factors: the first group of experimental factors are mainly the physical and mechanical parameters of the key layer; The second group of experiments retained the significant factors in the first group of experiments and considered the influence of the subcritical layer and the surface soil layer, the third group considered the key layer position, the stratification thickness and the physical and mechanical properties of the non-critical strata. 4th groups of experiments were carried out according to the physical and mechanical properties of coal seam, 5th groups of experiments retained the significant factors of 4th groups of experiments, and the effects of mining size and physical and mechanical properties of strata near coal seam were considered. 3) A single factor experiment is carried out on the significant factors obtained from orthogonal experiment, and the influence of these factors on the overlying strata movement is analyzed. The results of orthogonal experiment are verified. The main controlling factors for surface subsidence in strip mining are further determined. The final determinations of the main control factors for strip mining in near-shallow coal seam are: mining size (mining width, retaining width, mining height, subcritical layer thickness), which has certain influence on surface subsidence. However, the factors that influence the main key layer thickness, the elastic modulus and Poisson's ratio of the subcritical layer, the Poisson's ratio and the internal friction angle of the interlayer rock layer, the cohesion of coal pillar, and the internal friction angle and Poisson's ratio are the factors that influence the main key layer thickness and the subcritical layer's elastic modulus and Poisson's ratio. 4) based on the characteristics of cladding movement in strip mining of near-shallow coal seam, the mechanical model of sub-critical layer and main critical layer is established, and according to the relationship between the subsidence of the two layers, the deflection curve of the main critical layer is obtained through the deflection curve of sub-critical layer. The mechanical analysis of the sub-critical layer is carried out to verify whether the response of the established mechanical model to the main controlling factors conforms to the movement law of the overlying strata, and the results show that the surface subsidence curve is obtained by the deflection curve of the main key layer. The prediction method of surface subsidence under the condition of near shallow coal seam is put forward.
【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】：TD327

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