基于几何特征因子的粗糙裂隙氯代烃污染物传质模型研究

Chlorinated hydrocarbon contaminants seriously threats the subsurface environment and drinking water quality. Once chlorinated solvent was released into the subsurface, it can migration downward into fractured media and residual in it. It can create a potential long-term contamination, moreover, removing and remediating the residual blobs are difficult. Mass transfer from chlorinated solvent source is an important process for groundwater long-term contamination risk assessment. In prevenient researches, fracture models are not similar with natural fractures or the entrapment morphology was not obtained and the applicability of empirical mass transfer models are not satisfactory. To response these problems, we will carrying out transparent replica fracture experiments combine with fractal fractures model simulation in our researches. The main contents including trichloroethylene (TCE) and perchloroethylene (PCE) residual and dissolution tests, interfacial partitioning and bulk partitioning tracer tests and numerical simulations about TCE/PCE residual and dissolution process. The residual saturation, specific interfacial area, mass transfer coefficient and Sherwood number will be obtained, and the dissolution kinetics will be revealed. Mass transfer model will be created and modified using geometry characteristic factors (i.e. specific interfacial area, relative roughness or correlation length). The research achievement have important theoretical value and strategic significance for groundwater chlorinated solvent contamination assessment and control.

氯代烃有机化合物污染严重威胁着地下水环境与饮用水安全，主要是由于其一旦泄漏到地下，可沿着裂隙通道不断向下迁移并残留，造成去除和修复的困难。残留体的溶解传质问题，是地下水氯代烃污染长期风险评估的关键。针对已有模型试验不真实或未获得真实残留体结构、传质模型差异性大与适用性差等问题，本研究采用透明复制裂隙模型试验与分形裂隙数值模拟相结合的方法，开展三氯乙烯（TCE）和四氯乙烯（PCE）残留与溶解试验、界面和体积分配示踪试验以及残留与溶解数值模拟等内容，获取残留饱和度、比界面积、传质系数及舍伍德数等重要参数，揭示氯代烃残留体溶解的动力学特征，并基于残留体几何特征（比界面积）与裂隙几何特征因子（相对粗糙度、相关长度等），建立和完善粗糙裂隙的氯代烃传质模型。研究成果对于裂隙地下水中氯代烃污染的评估、控制具有重要的理论价值和战略意义。

氯代烃有机化合物污染严重威胁着地下水环境与饮用水安全，主要是由于其一旦泄漏到地下，可沿着裂隙通道不断向下迁移并残留，造成去除和修复的困难。残留体的溶解传质问题，是地下水氯代烃污染长期风险评估的关键。本研究采用透明复制裂隙模型试验与分形裂隙数值模拟相结合的方法，通过开展单裂隙溶质运移、DNAPL残留与溶解试验与数值模拟，获取残留饱和度、传质系数等重要参数，揭示氯代烃残留体溶解的动力学特征。溶质运移试验显示穿透曲线提前穿透和拖尾，粗糙裂隙溶质运移强烈依赖于隙宽的变化，窄隙宽是造成穿透曲线拖尾的重要原因之一。DNAPL残留体溶解指羽数值模拟结果表明，残留体数量和大小对传质具有显著影响。研究成果对于裂隙地下水中氯代烃污染的评估、控制具有重要的理论价值和战略意义。