气体运移导致煤体结构变形演化特征研究——以注入氦气为例

发布时间：2018-05-30 10:20

本文选题：注气 + 裂隙与基质　；参考：《岩土力学》2015年12期

【摘要】：气体运移引起煤体变形是研究煤层气抽采、预防瓦斯突出与温室气体的地质封存的核心问题。一般认为,有效应力变化是控制岩土类材料骨架变形的关键因素。但大量测试结果表明,煤的渗透率与有效应力(或者孔隙压力)表现出非线性关系。为此,应实时观测在静孔隙压力与三轴应力状态下氦气流动导致原煤变形演化全过程。在静孔隙压力状态下煤体积经历从收缩到回弹过程。注气压力越大,煤的收缩与回弹量越大,且收缩量总是大于回弹量。在三轴应力状态下注气初期煤样迅速膨胀。随着注气达到平衡状态,煤变形过程与约束条件表现出紧密相关性,即在应力约束下煤的膨胀率相比注气初期明显减缓;在位移约束下煤由膨胀转向收缩。上述试验结果表明,仅有孔隙压力作用下,煤基质与裂隙之间孔隙压力差可以压缩煤体,随着气体扩散的进行,可恢复煤的部分压缩变形量。在三轴应力状态下,煤的总体变形是裂隙与基质两者变形共同作用的结果。在应力约束下煤基质与裂隙可以自由膨胀。而煤体在位移约束下,因气体扩散导致煤基质膨胀只能挤压裂隙。根据上述实测结果探讨注气导致煤骨架变形演化机制,为深入理解煤裂隙与基质相互作用对煤渗透率演化提供试验依据。
[Abstract]:The deformation of coal body caused by gas migration is the core problem of coal bed methane extraction, prevention of gas outburst and geological storage of greenhouse gas. It is generally believed that the change of effective stress is the key factor to control the skeleton deformation of rock and soil materials. However, a large number of test results show that the permeability of coal shows a nonlinear relationship with effective stress (or pore pressure). Therefore, the whole process of deformation and evolution of raw coal caused by helium flow under static pore pressure and triaxial stress should be observed in real time. Under the static pore pressure, the coal volume experienced the process from shrinkage to springback. The larger the gas injection pressure, the greater the shrinkage and rebound of coal, and the shrinkage is always greater than the rebound. The coal sample expands rapidly at the initial stage of gas injection under triaxial stress state. With the equilibrium state of gas injection, the deformation process of coal is closely related to the constraint conditions, that is, the expansion rate of coal under stress constraint is obviously slower than that of gas injection at the initial stage, and the coal changes from expansion to contraction under displacement constraint. The experimental results show that the difference of pore pressure between coal matrix and fracture can compress the coal body only under the action of pore pressure, and the partial compression deformation of coal can be recovered with the gas diffusion. Under the condition of triaxial stress, the total deformation of coal is the result of the interaction of fracture and matrix deformation. Coal matrix and fissures can expand freely under stress constraint. Under the displacement constraint, coal matrix expansion caused by gas diffusion can only squeeze fissures. Based on the measured results above, the evolution mechanism of coal skeleton deformation caused by gas injection is discussed, which provides an experimental basis for further understanding the interaction between coal fissures and matrix on the evolution of coal permeability.
【作者单位】：山东科技大学矿山灾害预防控制国家重点实验室培育基地;中国矿业大学(北京)深部岩土力学与地下工程国家重点实验室;中国科学院武汉岩土力学研究所;长崎大学;
【基金】：国家自然科学基金(No.41202194,No.51474204,No.51134005) 山东省自然科学基金(No.ZR2012EEQ021) 中国博士后科学基金(No.2013M542097) 深部岩土力学与地下工程国家重点实验室开放基金(No.SKLGDUEK1421) 山东省“泰山学者”建设工程专项经费山东省高等学校青年骨干教师国内访问学者项目岩土力学与工程国家重点实验室开放基金(No.Z014006)资助~~
【分类号】：TD712.6

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