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关闭后再开发中岩土和环境风险的施工技术。本研究得到的主要结果可以总结如下：1。通过室内实验分析了垃圾处理过程中污染物的归宿和迁移。重金属和挥发性有机化合物（特别是致密的非水相液体）是这方面研究的重点。通过模型试验，分析了化学条件和微生物活动对沿海垃圾填埋场重金属迁移的影响。在典型的还原碱性条件下，重金属的迁移率明显降低，因为可还原部分受到影响，可氧化部分更有利。通过一系列的室内实验，对该工程衬垫系统在垃圾填埋场中的长期性能进行了评价。主要关注的问题有：(1)沿海垃圾填埋场关闭后再开发中作为地基结构的粘土层与钢桩之间的界面透射性；(2)暴露于渗滤液中化学物质和高温下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。开发了控制垃圾填埋场关闭后再开发中环境风险的施工技术，如土-膨润土混合物应用于垂直防渗墙和高稳定性工程填埋线的结构设计。在此研究成果的基础上，提出并讨论了适当的废物管理方案，包括废物的岩土工程利用和封闭堆填区的重建。

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.