垃圾填埋场黏土覆盖层孔隙结构演化特征及优势流机理研究

Aming at the key issue of the permeation in preferential flow effect in clay cover in landfill, based on the microscopic and macroscopic method, combining with the theory and numerical simulation, to study the evolution of pore structure in micro-macro condition in terms of a range of micro tests and model scale tests. The extended quantify attribute of the permeability and pore structure at co-effection would be proposed. The function between the permeability and porosity and water content of the clay cover in scales under fracture system occuring would also be developed. The soil-water retention curve model considered pore distribution under preferential pathway in the clay cover would be developed, to describe the variation of the micro-pore structure and macro water content in clay cover. A coupled mathematics model for describing the preferential flow considered evolution of the matrix and fracture pore strucuture would be developed to simulate the temporal and spatial variation of the process of permeation. This work would improved the preferential seepage theory, providing the theory evidence for failure evaluation of the impervious performance and optimization design of the final cover in landfill.

围绕垃圾填埋场黏土覆盖层优势流入渗的关键性科学问题，采用微观和宏观分析相结合、理论研究和仿真计算相结合的方法，通过一系列室内微观及模型体试验，研究优势路径条件下黏土覆盖层孔隙结构微观及宏观演化特征；提出黏土覆盖层渗透特征与孔隙结构协同演化过程中微观到宏观的扩展定量表征方法，并建立描述优势路径条件下黏土覆盖层渗透率-孔隙度-含水率变尺度统一协同表征模型；构建优势路径条件下考虑孔隙分布特征的黏土覆盖层土-水特征曲线模型，实现微观孔隙结构与宏观体积含水率之间的定量表征；构建考虑黏土覆盖层孔隙结构演化的优势流耦合数学模型，实现优势路径条件下孔隙结构和优势入渗演化过程的定量预测。研究成果可进一步丰富和完善优势渗流理论，同时为垃圾填埋场封场覆盖系统防渗性能的失效评价和优化设计提供理论依据。

围绕填埋场黏土的防渗的关键科学问题，采用宏观和微观试验相结合的方式，通过一系列室内微观、中试和现场试验，开展了黏土结构特征和优势流特征，对比研究了生物聚合物和传统膨润土改性压实粘土在干湿循环作用下的宏-微观结构与渗透特性演化规律，分析了典型工况对改性黏土宏-微观裂隙发育和渗透系数的影响机理。实现了填埋场垃圾土优势流的定量预测以及关键参数的反演，分析了典型工况对水分入渗及贮存状态的影响规律，为垃圾填埋场新型黏土覆盖层的设计提供了理论支撑。