蒸发条件下土体内部水分分布及变化规律研究

Study on Distribution and Change Laws of Soil Water Content due to Evaporation

土体在蒸发作用下丧失水分,易产生干缩裂隙,导致土体破碎,强度降低。采用数值模拟的方法,获得了蒸发条件下土体内部水分的分布特征和变化规律。温度越高,蒸发时间越长,表层土水分丧失得越快,影响的深度越大。土体体积含水率与深度的关系曲线与土水特征曲线、地下水位置、蒸发历时等密切相关。当地下水位较深或蒸发历时较短时,土体深部水分较难运移至表层土体,表层土体能够达到残余稳定状态,土体体积含水率与深度的关系曲线与土水特征曲线形态一致;当地下水位较浅或蒸发历时较长时,土体深部水分可不断运移至表层土体,表层土体达不到残余稳定状态,土体含水率与深度的关系曲线表现为负指数函数形式。

Desiccation cracks of soil are resulted from evaporation. It makes soil broken and the strength reduced. The distribution characteristics and change laws of soil moisture content due to evaporation are obtained by numerical simulation. The higher the temperature and the longer the evaporation time, the faster the rate of water loses and the deeper the influencing depth is. The soil volumetric water content-depth relationship is closely related to the SWCC, groundwater level and duration of evaporation. When the ground water level is low or the duration of evaporation is short, the deep soil water hardly transports to the surface soil and the residual steady state of surface soil can be achieved. The relation curve of soil volumetric water content and depth is similar to the SWCC. When the ground water level is high or the duration of evaporation is long, the deep soil moisture can be easily transported to the surface soil and the residual steady state of surface soil cannot be achieved. The relation curve of soil water content and depth shows negative exponential function.