Construction technologies and management in the post-closure redevelopment of waste landfill

本研究的主要目的是开发能够有效控制垃圾填埋场封场后再开发的岩土工程和环境风险的施工技术。本研究取得的主要结果如下：1.通过室内实验，分析了垃圾处理过程中污染物的迁移转化规律。重金属和挥发性有机化合物（特别是致密非水相液体）是本研究的主要关注点。通过模型试验，分析了化学条件和微生物活动对垃圾填埋场重金属迁移的影响。在典型的还原-碱性条件下，重金属的迁移率显著降低，这是因为可还原态受到影响，而可氧化态受到青睐.通过一系列的室内试验，对垃圾填埋场工程衬垫系统的长期性能进行了评价。主要关注的问题是：1）在封场后重建中，粘土层与作为地下室结构的钢桩之间的界面过渡; 2）暴露于渗滤液中的化学物质和高温下的衬垫的水力屏障性能; 3）钢桩在沿海垃圾填埋场垂直防渗墙中的应用。针对垃圾填埋场封场后再开发过程中的环境风险控制问题，提出了土-膨润土混合物在垂直防渗墙中的应用、高稳定性工程填埋线的结构设计等施工技术。在此基础上，提出并讨论了合理的垃圾管理方案，包括废弃物的岩土工程利用和封闭式垃圾填埋场的再开发。

The main objective of this research is to develop the construction technologies which can effectively control the geotechnical and environment risks in the post-closure redevelopment of waste landfill. The main results obtained in this study can be summarized as follows:1. Fate and transport of pollutants due to the waste disposal were analyzed by the laboratory experiments. Heavy metals and volatile organic compounds (particularly Dense Non-Aqueous Phase Liquids) are of main concern in this research. Particularly, heavy metal mobility in the coastal incinerator ash landfill was studied by analyzing the effects of chemical conditions and microbial activities with the model test. Mobility of heavy metals is significantly reduced under the typical reduced-alkaline condition, since the reducible fraction is affected and the oxidizable fraction is favored.2. Long-term performance of the engineered liner system in the waste landfill was evaluated through a series of laboratory experiments. The main concerns are 1) interface transmissivity between clay layer and steel pile installed at coastal landfill sites as the basement structure in the post-closure redevelopment, 2) hydraulic barrier performance of the liner exposed to the chemicals in the leachate and the high temperature, and 3) application of steel piles to the vertical cut-off wall in the coastal landfill.3. Construction technologies to control the environmental risks in the post-closure redevelopment of waste landfill were developed, such as the application of the soil-bentonite mixture to the vertical cut-off wall and the structural design of the engineered landfill line with the high stability. The scheme for proper waste management, including the geotechnical utilization of waste materials and the redevelopment of closed landfill, is proposed and discussed based on the achievements of this study.