顶板巷割缝特性及其对瓦斯抽采的影响研究

发布时间：2018-03-16 12:18

本文选题：顶板　切入点：钻孔　出处：《中国矿业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着我国经济的高速发展,煤炭的需求量也与日俱增,进而导致了煤炭的开采深度逐年增加,随之而来的是越来越严重的矿井瓦斯灾害。目前,煤层水力割缝卸压增透强化瓦斯抽采技术措施已经成为治理瓦斯灾害的主要技术手段之一。然而,当前的水力割缝技术措施主要布置底板巷穿层钻孔,顶板巷内水力割缝的相关现场实验缺乏广泛开展。针对此问题,采用理论分析、实验室物理实验、数值模拟和现场实验相结合的手段,对顶板巷内水力割缝特性及其对瓦斯抽采的影响进行研究,得到了如下主要研究成果:(1)根据顶板巷内钻孔角度的不同,将割缝过程中高压水射流分成淹没状态和非淹没状态,并分别阐述了二者的基本形态和动力学特征,建立了顶板巷钻孔内割缝堵塞的力学微分方程,并按现场实际参数予以验证,给出了顶板巷割缝的适用条件。(2)通过实验室物理实验,从试块表面应变变化特征反映出当对试块施加低压水射流冲击动载时上行钻孔扰动略强;当施加的水射流冲击动载进入中高压区段时,下行钻孔的扰动效果明显更为剧烈。进而观察试块的破裂特征发现,中高压区段的试块破裂表现出气蚀作用的影响。因此提出超前破坏范围的概念来解释下行钻孔内割缝具有更好扰动效果的现象,初步认为下行钻孔的破煤岩性能优越主要是由于存在表面空蚀阶段导致的。(3)采用数值模拟手段,对顶板巷水力割缝后煤层的残余瓦斯压力进行了分析。研究得到顶板巷进行水力割缝后,钻孔在垂直方向和水平方向上均存在强烈的耦合效应,钻孔之间互相强化,提高了单孔瓦斯抽采效率。进而分析认为,钻场布置的间距不能仅考虑单一钻孔的影响范围,还应当考虑钻孔之间的耦合作用,避免大量工程施工。对比了顶底板巷水力割缝的效果,发现顶板巷内水力割缝后煤层卸压消突区域具有更好的连通性和均匀性。(4)结合现场实验数据,得到顶板巷割缝后瓦斯抽采的浓度和纯流量均有提高,认为顶板巷水力割缝具有良好煤层卸压增透效果,同时对实验室物理实验和数值模拟实验的结果给予验证。以上研究成果对顶板巷内水力割缝的推广奠定了理论基础,对今后的现场施工具有明显的指导意义。
[Abstract]:With the rapid development of China's economy, the demand for coal is increasing day by day, which leads to the coal mining depth increasing year by year, followed by more and more serious mine gas disaster. The technical measures of pressure relief, antireflection and enhancement of gas drainage in coal seams have become one of the main technical means for gas disaster control. However, the current hydraulic seam cutting technology mainly arranges boreholes in floor roadways. The related field experiments of hydraulic slit in roof roadway are not widely carried out. In view of this problem, the method of combining theoretical analysis, laboratory physical experiment, numerical simulation and field experiment is adopted. The characteristics of hydraulic slit in roof roadway and its influence on gas drainage are studied. The main research results are as follows: 1) according to the different drilling angles in roof roadway, the high pressure water jet in the process of cutting seam is divided into submerged state and non-submerged state. The basic morphology and dynamic characteristics of the two are expounded respectively, and the mechanical differential equations of cutting joint blockage in roof roadway are established and verified according to the actual parameters in the field. In this paper, the suitable condition of roof roadway slit is given. (2) according to the physical experiment in laboratory, according to the characteristics of strain variation on the surface of the test block, the upward borehole disturbance is slightly stronger when the low pressure water jet impinges on the test block. When the applied water jet impinges the dynamic load into the middle and high pressure section, the disturbance effect of the downgoing borehole is obviously more intense. The fracture of the specimen in the middle and high pressure section shows the effect of cavitation, so the concept of leading failure range is put forward to explain the phenomenon that the internal cutting joint of downlink borehole has better disturbance effect. It is preliminarily considered that the superior performance of coal breaking rock in downlink drilling is mainly due to the existence of surface cavitation stage. The residual gas pressure of coal seam after hydraulic seam cutting in roof roadway is analyzed. It is found that there are strong coupling effects in vertical and horizontal direction after hydraulic seam cutting in roof roadway, and the boreholes reinforce each other. The efficiency of single hole gas extraction is improved, and it is concluded that the spacing of drilling field should not only consider the influence range of single borehole, but also consider the coupling action between boreholes. In order to avoid a large amount of engineering construction, the effect of hydraulic joint cutting in roof and floor roadway is compared, and it is found that there is better connectivity and uniformity in the area of pressure relief and outburst suppression after hydraulic slit in roof roadway. The concentration and pure flow rate of gas drainage are increased after cutting seam of roof roadway. It is considered that hydraulic cutting seam of roof roadway has good effect of pressure relief and antireflection of coal seam. At the same time, the results of laboratory physical experiments and numerical simulation experiments have been verified. The above research results have laid a theoretical foundation for the popularization of hydraulic joints in roof roadways, and have obvious guiding significance for the field construction in the future.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.6

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