School of Mines, MOE Key Laboratory of Deep Coal Resource Mining, China University of Mining and Technology
Guangzhou Urban Planning Design & Survey Research Institute
College of Energy and Mining Engineering, Shandong University ofScience and Technology

导水断层岩体的高渗透性为煤炭-水热型地热能高效协同开采提供了新思路,研究深部热-流-固耦合条件下断层岩体的渗透性演变规律是实现煤-热协同开采的重要前提。 自主研制了热-流-固耦合三轴试验系统,开展了导水断层岩体热-流-固耦合特性试验。 试验结果表明,热-流-固耦合作用下破碎岩体的渗透过程可以划分为冲蚀增透阶段及体缩抑流阶段,其中,冲蚀增透阶段发生在试验初期,岩体的渗透性参数(孔隙率、流速及渗透率)在该阶段迅速增长,进入体缩抑流阶段后保持小幅波动。 高温下岩石颗粒的热膨胀效应抑制了岩体孔隙空间扩展,导致渗透参数在冲蚀增透阶段增长缓慢;水压越高,渗透参数在冲蚀增透阶段增幅越大,表明高水压的冲蚀效应更显著;加载轴压与围压均会促进岩体的体缩效应,抑制渗透压力的冲蚀效果,导致试样渗透特性降低。 文章丰富了导水断层岩体热-流-固耦合特性研究,为煤-热高效协同开采提供了试验基础。

The high permeability of water-conducting fault rock mass provides a new idea for efficientco-exploiting of coal and geothermal energy. The permeability evolution law of fault rock mass underdeep thermal-hydraulic-mechanical (THM) coupling condition has become a prerequisite for the realiza-tion of co-exploiting of coal and geothermal energy. The THM triaxial test system was independently de-veloped and the permeability test of water-conducting fault fractured rock mass was carried out under thecoupling effect of THM. The test results show that seepage process of rock mass under THM couplingcan be divided into 2 stages: stage of erosion to increase permeability, stage of volume reduction to re-strain flow. Among them, the stage of erosion to increase permeability occurred in the initial stage of thetest, and the porosity, velocity and permeability of the fractured rock mass increased rapidly in thisstage, and then kept small fluctuations in stage of volume reduction and to restrain flow. The thermal ex-pansion effect caused by high temperature inhibits the expansion of pore space, as a result, the permea-bility parameters grow slowly in the Stage of erosion to increase permeability. The higher water pressureis, the greater the increase of permeability in the stage of erosion to increase permeability, indicating thatthe erosion effect of high water pressure is more significant. Both axial and confining pressure can causethe volume reduction effect of rock mass in fractured zone and inhibit the erosion effect of seepage, andlead to the decrease of permeability of the sample. This paper enriches the research on THM couplingcharacteristics of water-conducting fault rock mass, and provides laboratory test basis for efficient co-ex-ploiting of coal and geothermal energy.

国家自然科学基金项目(52122404,52130402)

1 断层岩体热-流-固耦合特性试验方法
1.1 破碎岩体THM三轴试验系统
1) 水压控制系统
2) 轴压控制系统
3) 围压控制系统
4) 温度控制系统
5) 数据采集处理系统
6) 模拟室
1.2 试样材料及试样制备
1.3 试验方案及流程
2 热-流-固耦合条件下渗透性表征方法
1) 孔隙率计算
2) 流速计算
3) 渗透率计算
3 断层岩体热-流-固耦合特征
3.1 全试样热-流-固耦合特征
1) 冲蚀增透阶段
2) 体缩抑流阶段
3.2 温度对断层岩体渗透性的影响
3.3 水压对断层岩体渗透性的影响
3.4 轴压对断层岩体渗透性的影响
3.5 围压对断层岩体渗透性的影响
4 结 论