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为揭示在渗流-化学溶解耦合作用下单裂隙渗透特性的变化规律,建立了描述二维渗流-化学溶解耦合作用的偏微分方程组,并利用COMSOL Multiphysics软件成功地求解该方程组。首先,模拟了文献[1]中的盐岩渗流-溶解耦合渗流试验结果,数值模拟结果与试验结果较为吻合,验证了数学模型的正确性和有效性。然后,利用分形理论生成了一个粗糙的裂隙面数字模型,着重分析了二维石灰岩粗糙裂隙面在水流、矿物溶解和输运过程中其渗透特性的变化规律。数值分析显示,(1)溶质浓度对裂隙面的溶解具有非常重要的作用,从而水流进口端的溶解厚度比出口端大得多。(2)裂隙的整体渗透性在初始时刻增加较慢,随着裂隙开度的增大和贯通,溶解速度会逐渐增大,是一个加速的过程。
In order to reveal the changing rules of single-fracture infiltration under the interaction of seepage-chemical dissolution and coupling, a partial differential equations describing the coupling of two-dimensional seepage-chemical dissolution were established. COMSOL Multiphysics software was used to solve this system. First, the seepage-dissolution coupling seepage test results of salt rock in [1] are simulated, and the numerical simulation results are in good agreement with the experimental results, which proves the correctness and effectiveness of the mathematical model. Then, a fractal theory is used to generate a rough fracture surface numerical model, which focuses on the analysis of the variation of the permeability characteristics of rough fracture surfaces of two-dimensional limestone in the process of water flow, mineral dissolution and transport. Numerical analysis shows that (1) the solute concentration plays a very important role in the dissolution of the fracture surface, and the dissolution thickness of the water inlet end is much larger than the outlet end. (2) The overall permeability of the fracture increases slowly at the initial time, and as the fracture opening increases and penetrates, the dissolution rate will gradually increase, which is an accelerated process.