大量早期垃圾堆场、填埋场因场底污染物扩散问题，逐渐成为重大环境安全隐患，目前较为普遍的处理方法是在场地周边构建竖向膨润土系隔离墙进行防污补强。前期研究中，膨润土大都用于降低天然土的渗透特性，而其对天然土半透膜效应改良、防污阻隔特性的提升少有涉及。因此，本项目将引入膨润土与天然土组成复合材料，针对渗滤液中四种主要污染物（无机盐、重金属、有机物、细菌微生物），研究复合土体材料半透膜效应阻隔特性、适用范围及应用条件；基于复合材料半透膜效应，进一步探究其对环境条件的响应，考虑影响因素包括膨润土掺量、压实度、土体厚度、溶液酸碱性、污染物浓度性状等；同时对复合土体材料进行细观表征，从物理化学两方面宏微观多角度揭示黏土矿物及其改性复合材料半透膜效应产生机理，进而提出半透膜效应特性的调控机制。预期研究成果在老旧垃圾堆场、填埋场竖向防污补强方面具有极高的现实价值，在城市生态文明建设方面应用前景广阔。

Since the diffusion of contaminant at the bottom layer, the early landfill site, a large amount of early built landfill site caused increasing potential threaten to the surrounding environment. Bentonite amended cut-off wall has always been applied for reinforcing the barrier performance. Previous researches were mostly focus on hydraulic behaviors of bentonite, however, little about the improvement in the membrane behavior of the bentonite. In this study, bentonite is introduced to promote the barrier performance of natural soil towards four types of contaminants (inorganic salt, heavy metals, organism and microbe), and enhance its membrane properties. In addition, different factors were studied to evaluate their effect on membrane behavior, including bentonite content, compactness, thickness, potential hydrogen of solution (pH), concentration and solute type. Further analysis was conducted to study the mechanism of the membrane behavior with the assistance of SEM images, X-ray diffraction (XRD) and X-ray fluorescence (XRF) results. The predicted results should be valuable in the field of reinforcing the barrier performance at the early landfill site or dumpsite.