煤层一维渗透失稳判别式建立及模拟试验

发布时间：2018-05-03 21:31

本文选题：煤与瓦斯突出 + 渗透失稳　；参考：《安徽理工大学》2017年硕士论文

【摘要】：为了确定含瓦斯煤体渗透失稳机制,根据易于发生突出的"构造煤"与土的工程性质相近的特点及国内外试验得到的煤层具有分层失去稳特征的结果,借鉴土力学关于流土问题分析方法,建立煤层一维渗透失稳判别式。提出"修正气压梯度"指标,认为当"修正气压梯度"达到"临界修正气压梯度"时,煤层发生渗透失稳。"临界修正气压梯度"与煤层抗剪强度成正比,与煤层暴露面半径成反比。为了验证该判别式的合理性,改进了试验装置并进行试验。渗透失稳试验装置主要包括煤样室,煤样压实装置,注气系统及气压测量系统。煤样粒径小于3.00mm,煤样长度为500mm,采用氮气为试验气体,球阀做为揭煤装置。进行了煤样在不同暴露面半径及不同抗剪强度影响下的对照试验;试验结果验证了该判别式的合理性,证明了煤样暴露面半径及抗剪强度等指标与其临界气压梯度的关系。研制相关试验装置进行了砂土暴露面半径对其临界水力梯度影响模拟试验,从而进一步探究已建立的判别式在砂土渗透破坏过程中应用的合理性,模拟试验装置主要包含土样室、加压系统、反力支架、隔水板、水头调节装置等,手动千斤顶用作土样加压装置,进行了砂土在不同圆形暴露面半径下的模拟试验;试验结果表明,砂土临界水力梯度随暴露面半径增大而减小。
[Abstract]:In order to determine the mechanism of seepage instability of gas-bearing coal body, according to the characteristics of similar engineering properties of outburst "structural coal" and soil, and according to the result of domestic and foreign tests, the coal seam has the characteristics of stratification and instability. Based on the soil mechanics analysis method of flow soil problem, a one-dimensional seepage instability discriminant for coal seam is established. The index of "modified pressure gradient" is put forward, and it is considered that when the "modified pressure gradient" reaches "critical modified pressure gradient", the seepage instability of coal seam will occur. " The critical modified pressure gradient is proportional to the shear strength of the coal seam and inversely proportional to the radius of the exposed surface of the coal seam. In order to verify the rationality of the discriminant, the test equipment was improved and the test was carried out. Seepage instability test equipment mainly includes coal sample chamber, coal sample compaction device, gas injection system and air pressure measurement system. The diameter of coal sample is less than 3.00mm and the length of coal sample is 500mm. Nitrogen gas is used as test gas and ball valve is used as coal uncovering device. A controlled test of coal samples under the influence of different exposure surface radius and different shear strength was carried out, and the results of the test proved the rationality of the discriminant and the relationship between the critical pressure gradient and the radius of the exposed surface and the shear strength of the coal sample. In order to further explore the rationality of the application of the established discriminant in the process of sand seepage failure, a simulation test on the influence of the exposed surface radius of sand on its critical hydraulic gradient has been carried out. The simulation test equipment mainly includes the soil sample chamber, pressure system, counterforce support, water barrier plate, water head adjusting device, etc. The manual Jack is used as the soil sample pressure device, and the simulation test of sand under different circular exposed surface radius is carried out. The experimental results show that the critical hydraulic gradient decreases with the increase of the exposed surface radius.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712

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