考虑蒸发影响的非饱和土坡渗流分析

运用分形模型理论预测了粘土、粉土与砂土的土-水特征曲线与导水系数曲线。讨论了大气降雨-蒸发作用对非饱和渗流场的变化规律。在大气蒸发作用下,粘土边坡表层土体的负孔压逐渐增大。随着降雨入渗,粘土边坡坡脚处的土体首先达到饱和状态,并出现正孔隙水压。在降雨过程中,粉土边坡与砂土边坡的坡脚处,难以形成正孔隙水压。粘土边坡的实际降雨入渗量较小,且与土体的初始含水量、降雨类型、土体的导水系数等因素有关。非饱和土的实际蒸发量不等于其饱和状态时的土体蒸发能力。当土体达到饱和状态时,两值相等。实际蒸发量与潜在蒸发量的比值是土体表层基质吸力的函数。

Analysis on Seepage of Unsaturated Soil Slope under Climatic Changes

With the method of fractal model to forecast the soil-water characteristics of unsaturated soil, it studies the process of unsaturated soil seepage under rainfall infiltration and evaporation related to climatic changes. Owing to the evaporation, the negative pore-water pressure increases gradually in the superficial layer of clayey soil slopes. The soils at the toe of the slope reach the saturated state at first while the retardation phenomenon occurs both at the surface and top of clayey soil slope. During the process of infiltration, positive pore-water pressure can be hardly generated at the toes of silt and sand slopes. The infiltration on the surface of clayey soil slope is small, and it is controlled by factors such as initial water content, rainfall type, hydraulic conductivity, etc. The rate of actual evaporation (AE) is only equal to the potential evaporation (PE) rate when the soil is saturated. The ratio AE/PE is the function of the suction.