随着工业化和城市化的快速发展,各类固体废弃物产量迅速增大,地下水土污染不断加剧,人类赖以生存的环境日益恶化。岩土工程研究者力图利用岩土工程的原理和方法来研究和解决这样的环境问题,并逐步形成了岩土工程学科的一个新兴分支——环境土工。环境土工问题伴随着生化反应、物理变化和机械运动等过程,目前国内外尚未建立统一的基本理论体系。该文论述了土体的生化反应、骨架变形、孔隙水运移、溶质迁移和孔隙气运移机理,并建立了考虑生化反应一骨架变形一水气运移一溶质迁移耦合作用的模型及其控制方程,界定并明确了模型参数及测试方法;揭示了高厨余城市固体废弃物填埋场存在严重的生化降解酸化抑制、骨架弱化和液气传导相互阻滞现象,以及城市固体废弃物压缩变形和液气产生及运移、污染物迁移与土体固结相互作用、污染物击穿防污屏障及覆盖屏障防水闭气的内在机理;结合笔者研究团队近二十年的环境土工研究和工程实践积累,总结了所提出的填埋场固废降解程度、渗滤液产量、填埋气收集率、填埋体沉降与填埋场容量、填埋场边坡稳定、防污屏障服役寿命评价方法以及所研发的填埋场液气立体导排、新型防污屏障和TDR污染土勘察技术的合理性和可靠性,并给出了工程应用实例。
With the rapid development of industrialization and urbanization, a large quantity of solid wastes have been produced, the groundwater and subsurface soils are seriously contaminated, and the environment which peoples rely on is getting worse. The researchers in geotechnical engineering make efforts to use the theories and approaches of geotechnical engineering to study and solve these environmental problems, and a new branch of geotechnical engineering discipline--environmental geotechnics has come into being. The problems of environmental geotechnics involve many processes including biochemical reaction, physical change and mechanical motion. A unified framework of the basic theories for environmental geotechnics has not been established currently. The mechanisms of biochemical reaction, soil skeleton deformation, pore water and gas transport and solute migration in soils are described. A coupled model and the relevant governing equations for biodegradation, mechanical deformation, fluid flow and contaminant transport in soils are established. The parameters in this model and their measuring methods are also addressed. The phenomena, serious acid inhibition caused by biochemical degradation, skeleton weakening and liquid-gas mutual blocking in the landfills of municipal solid wastes with high food content, are revealed. The mechanisms, including compression deformation and liquid/gas generation and transport in municipal solid wastes, interactionbetween pollutant migration and soil consolidation, pollutant penetrationof barrier and prevention of water infiltration and gas escape in landfill covers, are demonstrated. Based on nearlytwenty-year researches and practical works by the author's research group in environmental geotechnics, the proposed assessment approaches for the degradation degree of municipal solid wastes, leachate production, collection efficiency of landfill gas, landfill settlement and capacity, landfill stability and serving time of barriers in landfills are summarized, and the proposed tech