生活源污染黏性土结构与水理性质演化机理

Scientific subject that cooperative effect between contaminant seepage flow and chemical process on structure and water-physical properties of cohesive soil by taking organic as principal ingredient in life source contaminants is focused on. The research characterization and innovative ideas are highlighted with combining Soil Mechanics and Soil Science as well as Seepage Mechanics and Chemical, establishing a cohesive soil-life source contaminants coupling system, and exploring coupling relationship between cooperative effect relative with contaminant seepage flow as well as chemical system and clay engineering properties in the cohesive soil -life source contaminant coupling system. By means of combining indoors simulation experiments on contaminants seepage-chemical in cohesive soil, numerical simulation with engineering parctice test, and on basis of identifying the feature of the seepage flow and chemical process of life source contaminants and its cooperative effect on such properties as soil mineralogy, structure and water-physical properties of cohesive soil, the applicants attempt to study cooperative effect characterization parameters and their obtaining method of contaminant seepage folw-chemical; to emphasize and establish a quantitative relationship between cooperative effect characterization parameters of contaminant seepage flow-chemical and such cohesive soil parameters as pore space ratio，consistency index and permeability coefficient; to emphasize and establish a relationship model of cohesive soil-life source contaminants coupling system;further to explore the effect of cohesive soil macro structure on seepage and migrate of contaminants in cohesive soil; then to clarify spatial-temporal variation characteristics of micro-structure and water-physical properties of contaminanted cohesive soil by life source contaminants. Importantly, they expect to reveal evolution mechanism on structure and water-physical properties of contaminanted cohesive soil. Consequently, the research is aiming at searching evaluation methodology of contaminated cohesive soil properties, and laying the scientific foundation for the environmental impact assessment of contaminated cohesive soil, contaminant and geological hazard prevention.

聚焦有机质为主生活源污染质渗流、化学过程协同作用下黏性土结构、水理性质演化的科学问题，突出"土质学与土力学、渗流力学、化学知识融合、黏性土-生活源污染质耦合作用体系构建、体系内污染质渗流-化学协同效应及其与黏性土性质耦合关系探索"的研究特色和创新思路，采用黏性土的污染质渗流-化学实验模拟、数值模拟和工程测试相结合的方法，研究生活源污染质渗流、化学过程及其影响黏性土成分、结构和水理性质的协同效应，确定污染质渗流-化学协同效应表征参数及其获取方法，建立污染质渗流-化学协同效应参数与黏性土孔隙比、稠度指标、渗透系数等的量化关系和黏性土-生活源污染质耦合作用体系量化模型，探讨土体宏观结构对污染质渗流和迁移的影响，阐明生活源污染土结构与水理性质时空变化特征。以期揭示生活源污染土结构、性质演化机理，探索生活源污染土性质评价方法。为污染土环境质量评价、污染和地质灾害防治提供科学依据。

聚焦有机质为主生活源污染质渗流、化学过程协同作用下黏性土结构、水理性质演化的科学问题，突出黏性土-生活源污染质耦合作用体系构建、体系内污染质渗流-化学协同效应及其与黏性土性质和微观结构的研究思路，自主研发了渗流-化学协同作用的污染土样制备与性质测试一体化装置与试验方法，通过物理试验、数值模拟和现场测试方法，发现：有机质化学作用对黏土性质和微观结构的影响强于无机盐类、“低渗流深度阶段，生活源污染质对土体的作用首先为CH3COOH的化学作用，然后是渗流作用，提高了土体渗透性，降低了抗剪强度和压缩性；在高渗流深度阶段，有机物的降解产物与土体反应生成沉淀的化学作用，降低了土体渗透性和压缩性，提高了黏聚力”、“渗流和CH3COOH的化学作用增大了土体孔隙总面积、孔隙比，减低分形维数，而Ca-CO3则相反”等渗流和化学过程对黏性土性质、结构的协同效应。定义了淤堵物随渗流生成率、孔隙度随渗流降低率为协同效应表征参数。明确了表征参数的测试方法。阐明了淤堵物随渗流生成率、孔隙度随渗流降低率分别随渗流时间的增加而增大和减小，随渗流深度的增大而减小等时空变化规律。建立了包含协同效应参数、渗透系数、污染质浓度、基质吸力、渗流深度和时间等参数的黏性土-生活源污染质耦合作用体系量化模型，并给予求解和验证。土体宏观结构、污染质类型通过改变土体渗透性而影响污染质的渗流和运移。生活源污染土性质和结构的演化机理是：低深度阶段，有机质对土体的化学作用（改变颗粒吸附电荷平衡、溶解、腐蚀黏土矿物、螯合物生成）显现，同时，渗流力改变土体孔径和孔隙的作用较大。随着污染液渗流深度的增大，有机质降解和发酵产物---碳酸盐沉淀的生成和土体孔隙的填充。确定了包含4个递进步骤的生活源污染土性质评价方法。研究结论为污染土环境质量评价和地质灾害防治提供科学依据。已发表论文16篇，其中SCI检索6篇，EI检索3篇，获批发明专利2项。