HDPE膜-膨润土复合防污帷幕服役性能的离心模型试验及评价方法

HDPE geomembrane-bentonite composite barrier wall is believed as the most safe and effective isolation technique for underground contamination plume. However, its performance is far from being understood and engineers are short of assessment method. In this research, the water permeability and diffusion property of HDPE geomembrane and bentonite will be firstly measured. The centrifuge scaling laws for the solute transport through HDPE geomembrane-bentonite composite barrier wall will be investigated, and the corresponding centrifuge modelling method will be developed. Then, centrifuge modelling tests will be carried out on the keyed-in composite barrier walls to investigate the change of permeability along the depth of barrier wall, and the breakthrough process of different types of pollutants under different hydraulic head. A calculation method will be proposed for the breakthrough time of the keyed-in composite barrier wall. Centrifuge modelling tests and numerical analyses will be performed on the hanging composite barrier walls to investigate the influence of hydrogeology condition on the pathway of pollutants breaking through the barriers, and the corresponding assessment method will be proposed. On the basis of the research, a design method will be developed for the HDPE geomembrane-bentonite composite barrier wall. The design method takes a consideration of the hydrogeology conditions associated with the solid waste landfills located at a valley and a plain in China and the corresponding distribution of contamination plume. The research will provide theoretical basis and technical guide for the design and constrution of this new-type barrier wall.

HDPE膜-膨润土复合防污帷幕是最为安全有效的地下污染源阻隔技术，目前国内外对该新型帷幕服役性能的研究还不够深入,缺乏定量评价方法。本项目拟首先测试HDPE膜和膨润土的渗透和扩散特性，然后针对污染物通过HDPE膜-膨润土复合防污帷幕迁移问题，研究离心机模拟的相似性问题，并提出适合的离心模型试验方法。然后针对嵌入型复合防污帷幕，开展不同水头和污染物类型的离心模型试验，揭示膨润土墙防渗性能随深度变化规律及复合帷幕被污染物击穿的途径，提出嵌入型复合防污帷幕击穿时间计算方法。通过离心模型试验和数值模拟相结合的方法，研究水文地质条件对悬挂型复合防污帷幕击穿途径和击穿时间的影响，提出相应的评价方法。在此基础上，针对我国平原型和山谷型固废填埋场典型的水文地质条件和污染源类型及分布，提出HDPE膜-膨润土复合防污帷幕优化设计方法。该研究将为该新型帷幕科学设计、施工及推广应用提供理论依据和技术指南。

HDPE膜-膨润土复合防污帷幕是最为安全有效的地下污染源阻隔技术，目前国内外对该新型帷幕服役性能的研究还不够深入,缺乏定量评价方法。本项目提出了短土柱试验来测定黏性土等温吸附曲线的方法，完善了膨润土的扩散和吸附特性测试方法，并测试了膨润土基材料（黄土-粉土-膨润土混合回填料和膨润土-渣土混合回填料）的渗透、扩散和吸附特性。建立了有机物通过HDPE膜-膨润土复合防污帷幕扩散解析评估方法，分析了非线性吸附作用、隔水层深度、土层渗透系数、帷幕插入深度以及污染物参数变异性对防污帷幕击穿时间的影响。研究了黏土防污帷幕污染物迁移离心模拟机械弥散作用和吸附作用相似性，提出了基于离心模型试验缩时试验的防污帷幕击穿时间评估方法。研发了可应用于黄土改性粉土-膨润土竖向帷幕服役性能离心模型试验装置，开展了嵌入型粉土-膨润土竖向帷幕离心模型试验，获得了防污帷幕百年尺度击穿时间试验验证方法。提出了浅部增强型土-膨润土竖向防污帷幕的优化设计方法，并在淮南市采煤塌陷区垃圾场封场工程中得到运用。截止2017年12月，研究课题累计录用发表论文16篇，SCI论文7篇，EI论文6篇，中文核心期刊1篇，会议论文2篇，会议特邀报告4篇，授权国家发明专利3项，专利技术实施权转让1项，研究成果直接应用于工程项目2项。