非饱和土渗流计算收敛准则及细粒-粗粒土毛细隔离层的防渗机理和设计理论

As a newly developed anti-seepage design, multi-layer capillary barrier(MCB) is economy and shows great advantage in strength and deformation comparing to clay or geo-membrane. In the past decades, researchers studied the applicability of capillary barrier for covering the landfill of waste. The mechanisms and anti-seepage ability of MCB involving coarse soil still desire some progress in the following field: (1) the accuracy and convergence of seepage problem involving unsaturated coarse soil which has a highly non-linear permeability function; (2) the design theory of MCB. This project tries to solve upper two problems. First, the convergence criteria of seepage analysis for unsaturated soil are to be derivated and program are to be developed. Second, the design theory are to be established with the considering of micro flow in soil porosity. Third, laboratory model test and soil column test are used to study the infiltration process in soil column and slope with multi-layer soil. Fourth, back analysis will be carried out to check the validation of the convergence criteria of seepage analysis for unsaturated soil. Fifth, design chart and table will be proposed based a seris numerical simulation of MCB and the laboratory test results.

近年来，细粒-粗粒土毛细隔离层开始用于边坡防渗和垃圾填埋场的封场覆盖。细粒-粗粒土毛细隔离层利用非饱和粗粒土的毛细阻滞效应进行防渗。目前，有关细粒-粗粒土毛细隔离层的研究还非常稀少，缺少相关的计算模型，渗流分析方法和设计理论。为填补这方面的空白，本项目拟：（1）针对非饱和粗粒土渗透系数函数的强非线性特征及网格时步敏感性，推导非饱和土渗流计算收敛准则，并开发网格自适应渗流计算程序；（2）基于土体微观孔隙结构，推导细粒-粗粒土毛细隔离层的工作条件和设计准则，给出细粒土层容许持水量，结构失效条件的计算公式；（3）开展土柱实验和倾斜细粒-粗粒土层模型实验，研究细粒-粗粒土毛细隔离层的防渗性能和渗透稳定性，验证细粒-粗粒土毛细隔离层的设计准则（4）通过数值反演验证非饱和渗流计算收敛准则和计算程序；（5）通过数值模拟和分析，为垃圾填埋场的封场覆盖给出直观的细粒-粗粒土毛细隔离层设计图表。

绝大多数的边坡、路基，大部分的地基、隧道和基坑都由非饱和土构成或建造在其之上。非饱和土防渗技术以及非饱和冻土变形是当今非饱和土领域的焦点问题。在国家自然基金的支持下，申请人4年对这两个焦点展开了深入的研究，取得了很多原创性的成果。在此期间，项目负责人共发表项目标注论文12篇，其中SCI论文4篇，EI论文8篇。主要的研究内容和成果如下：.1/ 提出了一种导排型毛细阻滞防渗层，增加了毛细阻滞防渗层的可靠性和适用性。.2/ 完善了传统毛细阻滞防渗层的设计理论和计算方法，可以指导工程实践。.3/ 提出了非饱和土冻土的统一变形和强度理论，能够用于任意初始含水率，任意初始干密度条件下非饱和土冻结变形和冻结强度预测。该模型能够用于非饱和土有限元分析，弥补了传统模型精度不足的缺陷。