【摘要】 目的：嵌入式土-膨润土防污阻隔墙的嵌入部分对其服役性能至关重要。本文通过开展离心模型试验，探讨嵌入部分对污染物迁移的影响，以期为嵌入式砂-膨润土防污阻隔墙的施工设计提供指导。创新点：1.首次通过离心模型试验模拟了嵌入式砂-膨润土防污阻隔墙内的污染物运移；2.通过在数值模拟中添加裂隙这一内部边界条件，成功模拟了污染物的界面优势运移，使得模拟结果与试验结果吻合。方法：1.通过离心模型试验，获得嵌入式土-膨润土防污阻隔墙服役36小时（相当于原型41年）后的污染物浓度分布；2.通过分析模型的渗漏量和阻隔墙内污染物浓度分布，探究阻隔墙嵌入部分与弱透水层界面处污染物的运移行为；3.通过小尺度染料示踪试验，验证界面优势运移的存在；4.通过界面优势运移的数值模拟，验证所提方法的可行性，并探究嵌入式砂-膨润土防污阻隔墙的击穿时间和服役寿命。结论：1.阻隔墙的水平有效应力随深度先增加后减小，这与一些现场测量结果一致；2.在阻隔墙嵌入部分与弱透水层之间的界面存在污染物的优势运移，污染物沿着界面迅速运移，绕过阻隔墙的底部并到达下游；3.在数值模型中使用裂缝这一内部边界来模拟界面优势运移，模拟结果与离心试验结果较为吻合；4.界面优势运移作为一种缺陷，大大加快了污染物的运移速度，将阻隔墙的击穿时间缩短到没有界面优势运移时的1/9;5.在实际工程中，当原位土壤为粒径较大的砂土时，应使用粒径较小的粉土或粘土作为砂-膨润土防污阻隔墙的基土，以防止界面优势运移的产生。更多还原

【Abstract】 Sand-bentonite(SB) cutoff walls are commonly used as barriers in polluted areas.The embedded part of an SB wall in an aquitard is crucial for its performance.In this study,a centrifuge modeling test was carried out to investigate the effect of contact between the key and the aquitard on the migration behavior of contaminants within an SB cutoff wall.The centrifuge was accelerated to 100g(gravitational acceleration) and maintained in-flight for 36 h,equivalent to 41 years of transport time in the prototype.Results showed that the contaminant concentration within the SB wall was higher downstream than in the middle in the thickness direction,and deeper regions exhibited a greater concentration than shallower ones.This concentration distribution indicated that contaminants were transported along the interface between the SB wall and the aquitard,bypassing the base of the SB wall to reach the downstream aquifer rapidly.An improved numerical simulation considering preferential interface migration was performed,which agreed with the centrifuge test results.The simulation results indicated that preferential interface migration,as a defect,significantly accelerated the speed of contaminant migration,reducing the breakthrough time of the SB wall to 1/9 of that without preferential interface migration.更多还原