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均质土质覆盖层作为填埋场与大气环境的隔离结构其主要功能是控制雨水入渗,近些年该类覆盖层在北美一些干旱和半干旱地区被证明是有效的。基于二维非饱和土渗流控制方程,采用可考虑土体进气值的指数函数描述土体的土水特征曲线和渗透系数曲线,使用单位梯度边界作为土质覆盖层的底部边界条件,推导出可考虑任意初始条件的降雨入渗移解析解。通过与前人试验结果比较与分析,证明了该解析解的有效性。对比分析了均质土质覆盖层底部分别取单位梯度边界、渗流审查边界和固定孔压边界对降雨入渗及渗漏量的影响,分析结果表明:与渗流审查边界和固定孔压边界相比,单位梯度边界更适合土质覆盖层的渗漏量计算。利用该解析解分析不同初始条件对累计渗漏量的影响,结果表明覆盖层累计渗漏量随其底部初始体积含水率的增加而增大。为土质覆盖层防渗漏性能评价提供了一种简单实用的计算方法。
The main function of a homogeneous soil cover as an isolated structure of the landfill to the atmosphere is to control rainfall infiltration, which in recent years has proven to be effective in some arid and semi-arid North American regions. Based on the seepage control equation of two-dimensional unsaturated soil, the soil-water characteristic curve and permeability coefficient curve can be described by the exponential function that can consider the value of soil gas intake. Using the unit gradient boundary as the bottom boundary condition of soil cover, Analytical solution of rainfall infiltration considering arbitrary initial conditions. By comparing with previous experimental results, the validity of this analytical solution is proved. The effects of unit gradient boundary, seepage boundary review and fixed pore pressure boundary on rainfall infiltration and leakage were compared and analyzed. The results show that compared with seepage boundary and fixed pore pressure boundary, The unit gradient boundary is more suitable for calculation of seepage quantity of soil cover. The analytical solution is used to analyze the effect of different initial conditions on the cumulative leakage. The results show that the accumulated leakage of the overburden increases with the increase of the initial volumetric water content at the bottom. It provides a simple and practical method for evaluating the seepage resistance of soil cover.