蒸发蒸腾作用下非饱和土的吸力和变形影响因素分析

On influence factors of suction and deformation of unsaturated soil under evaporation and transpiration effect

采用热湿耦合非等温流方程,结合实际蒸发和植物蒸腾的边界条件,考虑了水分迁移所引发的非饱和土应力变形行为,从而建立了大气-非饱和土相互作用模型。采用该模型对控制非饱和土吸力和变形的大气蒸发和植物蒸腾等多参数进行了影响程度分析。结果表明,控制地面吸力和变形的主导因素是外部气象条件,尤其太阳净辐射量和风速,土体水力和热力特性参数影响程度有限;在植被覆盖条件下,吸力变化主要取决于植物叶面积指数LAI,而总腾发量的大小决定了地表变形量。

Based on the equations of coupled heat-moisture anisothermal flow and the behaviors of stress-strain of unsaturated soil,an interaction model of atmosphere-unsaturated soil is established with the boundaries of actual evaporation and vegetation transpiration.The influence of climatic evaporation and vegetation transpiration on the suction and deformation of soil surface are analyzed by the interaction model.It is shown that the major governing factor for the suction and deformation of soil surface is outer climatic condition where solar net radiation and wind velocity are the most contribution,while the internal hydraulic and thermal parameters of soil property play a less role in the estimation of evaporation.With the cover of vegetation,the behavior of suction depends on the leaf area index（LAI）,while the magnitude of total evaporation and transpiration determines the deformation of soil surface.