煤层钻孔膨胀致裂及增透特性研究

发布时间：2018-03-22 20:55

本文选题：膨胀材料　切入点：钻孔致裂　出处：《华北理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：瓦斯灾害事故严重影响着煤矿的安全和生产效率。钻孔抽放是瓦斯灾害事故的主要防治措施之一,但由于我国的大部分煤层属于低透气性煤层,瓦斯抽放效果较差,达不到瓦斯治理的目的。为了更有效地对煤层瓦斯进行抽放,增加煤层透气性和扩大瓦斯抽放半径是提高瓦斯抽放效率的关键。通过理论研究与实验室试验相结合的方法对膨胀材料致裂机理进行了研究,并分析了时间、环境温度、水灰比、孔径大小等因素对膨胀材料水化反应的作用效果。通过实验确定了磷酸钠、三聚磷酸钠、柠檬酸钠、硼砂、石膏的缓凝剂的凝结时间;通过配比试验及膨胀压力测定,确定膨胀压力为45~65MPa,并且通过添加掺和料可以控制膨胀材料的膨胀压力、最高反应温度、反应速率。基于煤体力学特性,利用相似材料试验和COMSOL数值模拟软件对煤层钻孔致裂和钻孔抽放瓦斯进行了分析研究。相似材料试验表明当膨胀材料配制比例的减少时,反应时间也随之减缓,致裂产生的3~4条主裂隙宽度也相对较小。数值模拟结果显示通过煤层钻孔膨胀致裂,能够扩大瓦斯抽采有效范围,提高瓦斯抽采效果。研究结果表明,相对于传统钻孔抽放瓦斯技术,在煤层中合理布置一定的膨胀钻孔,对其灌注膨胀材料,依靠其产生的膨胀压力促使钻孔周边煤体破裂,可增大钻孔瓦斯有效抽放范围和煤层的透气性,大大缩短了瓦斯预抽时间,从而解决低透气性煤层开采过程中瓦斯抽放问题。
[Abstract]:The gas disaster accident seriously affects the safety and production efficiency of coal mine. Borehole drainage is one of the main prevention measures of gas disaster accident, but because most coal seams in our country belong to low permeability coal seam, the effect of gas drainage is poor. The purpose of gas control cannot be achieved. In order to drain coal seam gas more effectively, Increasing the permeability of coal seam and enlarging the radius of gas drainage are the key to improve the efficiency of gas drainage. The cracking mechanism of expansion material is studied by combining theoretical research with laboratory test, and the time and environment temperature are analyzed. The effect of water-cement ratio, pore size and other factors on hydration reaction of expansive materials was studied. The setting time of sodium phosphate, sodium tripolyphosphate, sodium citrate, borax and gypsum retarder was determined by experiments. The expansion pressure is determined to be 45 ~ 65 MPA, and the expansion pressure, maximum reaction temperature, reaction rate of the expansive material can be controlled by adding the admixture, based on the mechanical properties of the coal, The similar material test and COMSOL numerical simulation software were used to analyze and study the borehole fracturing and gas drainage in coal seam. The similar material test showed that the reaction time also slowed down when the proportion of expansion material was reduced. The results of numerical simulation show that the effective range of gas drainage can be expanded and the effect of gas extraction can be improved by the expansion of borehole in coal seam. Compared with the traditional borehole gas drainage technology, a certain expansion borehole is reasonably arranged in the coal seam, and the swelling pressure produced by the expansion material can promote the coal body fracture around the borehole. It can increase the effective drainage range of borehole gas and the permeability of coal seam, greatly shorten the time of gas pre-drainage, thus solve the problem of gas drainage in the mining process of low permeability coal seam.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.6

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