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工程科学与技术:2018,50(4):55-62
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常规三轴压力下含瓦斯煤蠕变–渗流演化规律
(1.中国矿业大学(北京) 资源与安全工程学院, 北京 100083;2.煤炭资源与安全开采国家重点实验室, 北京 100083;3.河南省瓦斯地质与瓦斯治理重点实验室 省部共建国家重点实验室培育基地, 河南 焦作 454000;4.中国长江三峡集团有限公司移民工作局, 北京 100038)
Evolution of Gas-filled Coal Creep-seepage Under Conventional Triaxial Compression
(1.School of Resources and Safety Eng., China Univ. of Mining & Technol. (Beijing), Beijing 100083, China;2.State Key Lab. of Coal Resources and Safe Mining, Beijing 100083, China;3.State Key Lab. Cultivation Base for Gas Geology and Gas Control, Jiaozuo 454000, China;4.China Yangtze River Three Gorges Group Co., Ltd. Immigration Bureau, Beijing 100038, China)
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投稿时间:2018-01-30    修订日期:2018-05-26
中文摘要: 在瓦斯抽采、煤层气开采及煤与瓦斯突出过程中,煤岩蠕变引起岩体变形会对瓦斯渗流产生影响。为研究含瓦斯煤蠕变–渗流的演化规律,得到蠕变–渗流的耦合关系,作者进行了不同瓦斯压力下分级加载轴压时煤体常规三轴蠕变–渗流试验。试验结果发现:轴向应变呈梯度增大,直至煤样破坏;期间,煤体内部瓦斯渗透率呈先减小后增大的趋势。这表明煤样蠕变过程中煤体内部孔隙或微裂隙发生了两次变化:前期蠕变过程中,孔隙或微裂隙压密,瓦斯流通受阻渗透率减小;当应变超过一定阈值时,煤体骨架发生变化,孔隙或微裂隙出现增生或扩展,瓦斯通道贯通渗透率增大。此外,由试验结果可知,煤岩发生失稳破坏时,必须具备应力超过长期强度、应变超过应变阈值两个条件。这一结论为煤岩失稳破坏提供了一条新的思路。进而,为进一步研究蠕变变形和渗透率的关系,基于Kozeny-Carman公式进行合理地假设及推导,得到应变与渗透率的数学关系式。最后,利用蠕变–渗流试验数据验证时,发现应变–渗透率公式能很好地反映蠕变–渗流过程中的耦合规律。结论能为应力场–裂隙场–渗流场耦合研究提供一定的参考价值。
Abstract:The creep of coal rock has an effect on the gas permeability during methane extraction, coal bed gas exploitation and coal and gas outburst in mines. It is important to study the evolution of gas-filled coal creep-seepage and to obtain the coupling relationship between creep and seepage. In this paper, the evolution of gas-filled coal creep-seepage at different gas pressures was tested under conventional triaxial compression. The results showed that the axial strain grew by degrees as the stress increased step by step, until the destruction of coal samples. On the other hand, the gas permeability of coal was declined first and then raised, which can be concluded that micropores and microcraks within the coal body went through two changes. When the stress was less than the long-term strength of coal, the micropores and microcraks were closed; the gas seepage channels were blocked and then the gas permeability was on the decline. While the stress was greater than the long-term strength or the strain was greater than the strain-threshold of coal, the gas seepage was raised. The micropores and microcraks were adjoined and the gas seepage channels were expanded. Therefore, it is suggested that the stress exceeding long-term strength and the strain reaching a threshold are the prerequisites for the instability of coal and rock, which indicates a new way to study coal rock failure. Based on Kozeny-Carman formula, reasonable hypothesis and deduction, the coupling formula between strain and permeability was obtained. Moreover, this coupling formula was validated by the test data. The above findings would play an important role in the development of the stress field, fracture field and seepage field coupling theory.
文章编号:201800099     中图分类号:    文献标志码:
基金项目:国家重点研发计划资助项目(2016YFC0600708);国家自然科学基金资助项目(51304212);中央高校基本科研业务费专项资金资助项目(2009QZ09);河南省瓦斯地质与瓦斯治理重点实验室——省部共建国家重点实验室培育基地开放基金项目资助(WS2018B04)
作者简介:李祥春(1979-),男,副教授,博士生导师,博士.研究方向:瓦斯灾害防治.E-mail:chinalixc123@163.com
引用文本:
李祥春,张良,赵艺良.常规三轴压力下含瓦斯煤蠕变–渗流演化规律[J].工程科学与技术,2018,50(4):55-62.
LI Xiangchun,ZHANG Liang,ZHAO Yiliang.Evolution of Gas-filled Coal Creep-seepage Under Conventional Triaxial Compression[J].Advanced Engineering Sciences,2018,50(4):55-62.