复合温度条件下石灰岩多场耦合裂隙渗透侵蚀试验研究

深部岩石工程处在高应力、高水压力、高地热等复杂地质环境中,这些因素相互作用将对岩石的渗透特性产生重要影响,进而影响深部岩石工程的安全和生产效率。通过开展不同温度(25℃~90℃)条件下的同一块石灰岩裂隙多场耦合渗透特性变化试验,得到了温度因素对石灰岩裂隙渗透特性的影响规律。试验结果表明:在恒定有效压力作用下,升温阶段的初始时刻有一个流量峰值过程,温度恒定时,流量缓慢减小并最终趋于稳定状态;温度升高使得岩石裂隙渗透率单调下降,裂隙开度进一步减小;此外,温度越高,初始阶段裂隙开度闭合速度快,趋于稳定开度值历时越短且最终稳定开度值越小。石灰岩的侵蚀溶解速度随温度的升高而加快,裂隙面溶解出的矿物质增多,因此,渗出液中各离子的浓度随温度的升高变大。

Evolution of rock fracture permeability in coupled processes with variable temperatures

The projects in deep rock are under complex geological environment of high stress, high water pressure, high heat, etc. These factors may have important influences on the permeability in fractured rock and further on the safety and productivity of deep rock projects. Flow-through tests on an artificial fracture in limestone are conducted at 25℃~90℃. The effects of different temperatures on the evolution of permeability in fractured rock are studied. The results show that at the initial stage of heating, the flow has a peak under constant effective stress. It decreases slowly until one steady count at constant temperature at last. The fracture permeability declines monotonically with the increasing temperature under constant effective stress. Faster speeds of fracture closure at the initial stage, shorter time required for stabilization and smaller aperture at the final equilibrium under higher temperatures can also be observed. The solubility speed and dissolved mineral matter of limestone increase with the increasing temperatures.