非饱和土的蒸发效应与影响因素分析

采用非饱和土等温流和考虑热湿耦合的非等温流方程，结合不同的蒸发计算模型，分析了大气蒸发效应对非饱和土吸力变化的影响，并对控制蒸发量计算的多个参数进行了影响程度分析。结果表明，考虑实际蒸发量和非饱和土热湿耦合的水分运动公式能较好地模拟大气影响下非饱和土吸力变化状态，通常所采用的等温流方程加以潜在蒸发量计算非饱和土吸力变化会高估表层蒸发和吸力的下降程度。控制地面蒸发的主导因素是外部气象条件，尤其以太阳净辐射量和风速为最，土体自身特性参数影响程度有限。

Evaporation effect in unsaturated soil and its influential factors

Evaporation effect on the suction in the unsaturated soils is analyzed by solving the equations of isothermal flow and coupled heat-moisture anisothermal flow with various calculated models of evaporation. The influences of various climatic parameters and soil properties on the calculation of evaporation are also discussed. It is shown that the behavior of suction in the unsaturated soil can be perfectly modeled by the equation of coupled heat-moisture anisothermal flow with the formulation of considering actual evaporation and commonly-used methods by solving isothermal flow with the boundary of potential evaporation evidently overestimate the evaporation magnitude in the soil surface and the decreasing magnitude of suction. The major governing factor for the evaporation of soil surface is outer climatic condition where solar net radiation and wind velocity are the most contribution, while the internal parameters of soil property play a less role in the estimation of evaporation.