液态二氧化碳相变致裂增透机理研究

发布时间：2018-05-03 22:11

本文选题：液态二氧化碳相变致裂 + 致裂当量　；参考：《河南理工大学》2014年硕士论文

【摘要】：液态二氧化碳相变致裂增透技术作为一种新型的强化抽采瓦斯技术,在其致裂机理、合理布孔参数等方面研究不足。本文采用理论分析、数值模拟和现场试验的手段,在现场试验液态二氧化碳相变致裂的基础上,分析了液态二氧化碳相变致裂增透的效果;通过选择合理计算方法,计算得出了液态二氧化碳相变致裂的当量,通过致裂试验验证与数值模拟结果的一致性,采用数值模拟的方法研究了煤层瓦斯压力对致裂效果的影响,分析了致裂产生的高能二氧化碳气体和瓦斯气体作用下的裂纹扩展及破坏准则,总结了液态二氧化碳相变致裂增透的机理。首先,在总结国内外研究成果的基础上,介绍了液态二氧化碳相变致裂新技术,通过在河南焦煤能源有限公司九里山矿的现场试验,分析了该致裂增透技术的效果和在煤矿应用范围,对比了液态二氧化碳相变致裂技术与高压水射流扩孔技术的增透效果,得出了经液态二氧化碳相变致裂的钻孔瓦斯抽采量与高压水射流扩孔的钻孔瓦斯抽采量相比提高1.44~5.2倍,证明了液态二氧化碳相变致裂技术强化预抽煤层瓦斯的优越性,具有很高的经济价值。其次,利用有限元分析软件ANSYS_LS-DYNA3D对致裂当量和在煤体中致裂时的应力场进行数值模拟。以断裂力学理论为基础,建立了含瓦斯压力条件下煤的体致裂作用计算模型;分析了致裂时煤体中应力场的分布规律,通过分析致裂产生的高能二氧化碳气体和瓦斯气体作用下煤体内的应力场及裂纹扩展情况,提出了液态二氧化碳相变致裂增透的机理。最后,在岩石爆破理论的基础上,分析了致裂产生的高能二氧化碳气体和瓦斯气体在煤体致裂损伤断裂过程中的作用,以及瓦斯气体对煤体主要物理力学性质的影响,根据损伤断裂力学理论计算了致裂应力波形成的初始宏观裂纹尖端的有效应力强度因子,分析了致裂产生的高能二氧化碳气体和瓦斯气体作用下裂纹的扩展过程,并确定了裂纹的扩展准则。结合前期的试验结果进一步验证理论分析研究结论的正确性与合理性。
[Abstract]:As a new type of enhanced gas extraction technology, liquid carbon dioxide phase change and antireflection technology has not been studied in terms of its cracking mechanism and reasonable pore layout parameters. In this paper, by means of theoretical analysis, numerical simulation and field test, the effect of liquid carbon dioxide phase change induced cracking and antireflection is analyzed on the basis of field test, and reasonable calculation method is selected. The equivalent of liquid carbon dioxide phase transformation is calculated. The effect of coal seam gas pressure on fracture effect is studied by using numerical simulation method, which is consistent with the results of numerical simulation. The crack propagation and failure criteria under the action of high energy carbon dioxide gas and gas gas are analyzed, and the mechanism of liquid carbon dioxide phase transition induced crack and antireflection is summarized. First of all, on the basis of summarizing the domestic and foreign research results, the paper introduces the new technology of liquid carbon dioxide phase change cracking, through the field test in Jiulisshan Mine of Henan Coking Coal Energy Co., Ltd. The effect of this technology and its application in coal mine are analyzed. The antireflection effect of liquid carbon dioxide phase change technology and high pressure water jet reaming technology is compared. It is concluded that the amount of gas extracted from the borehole induced by liquid carbon dioxide phase change is 1.44 ~ 5.2 times higher than that of the high pressure water jet reaming hole, which proves the superiority of the liquid carbon dioxide phase transformation technology in enhancing the pre-drainage of coal seam gas. Have very high economic value. Secondly, the finite element analysis software ANSYS_LS-DYNA3D is used to simulate the crack equivalent and stress field in coal. Based on the theory of fracture mechanics, the calculation model of coal body fracturing under the condition of gas bearing pressure is established, and the distribution of stress field in coal is analyzed. Based on the analysis of stress field and crack propagation in coal under the action of high energy carbon dioxide gas and gas produced by cracking, the mechanism of cracking and antireflection caused by liquid carbon dioxide phase transformation is put forward. Finally, on the basis of rock blasting theory, the effect of high energy carbon dioxide gas and gas gas produced by cracking on the fracture process of coal body and the influence of gas gas on the main physical and mechanical properties of coal body are analyzed. According to the theory of damage fracture mechanics, the effective stress intensity factor at the tip of the initial macroscopic crack formed by the crack stress wave is calculated, and the crack propagation process under the action of high energy carbon dioxide gas and gas gas produced by the crack is analyzed. The crack propagation criterion is determined. The correctness and reasonableness of the theoretical analysis results are further verified by the previous test results.
【学位授予单位】：河南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TD712.6

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