基于降雨入渗全过程的非饱和湿润峰模型

对降雨入渗过程进行研究有助于充分发挥土壤的蓄水能力,减缓城市管网的泄洪压力。为更真实地反映入渗过程中土壤的含水率分布情况,将降雨入渗过程进行分段,确定各阶段土壤含水率分布函数,提出了修正的非饱和湿润峰模型。同时,结合达西定律,引入土体非饱和参数,得到均匀土体在不同降雨强度下,土壤含水率、浸润深度和累计入渗量随时间变化的曲线。结果显示,入渗过程中土壤表层含水率和浸润深度随时间呈非线性变化。对于高强度降雨,当表层土壤饱和后,开始出现积水。累计入渗量最终取决于土壤的饱和渗透性质,降雨强度对其影响有限。分别将4种土质土体的计算结果与有限元法得到的结果进行对比,两者相对偏差均小于5%。

Unsaturated wetting front model based on the whole process of rainfall infiltration

The study of rainfall infiltration process is helpful for soil to give full play to its water storage capacity, so as to alleviate the flood discharge pressure of urban pipeline network. In this paper, the rainfall infiltration process is segmented to determine the distribution function of soil water content in each stage, and a modified unsaturated wetting front model is proposed. In addition, combined with the Mein-Larson model, the soil unsaturated parameters were introduced to analyze the changes of soil moisture content, infiltration depth and cumulative infiltration with time under different rainfall intensities. The results show that the water content of the surface soil and infiltration depth change nonlinearly with time during the infiltration process. For high-intensity rainfall infiltration,when the surface soil is saturated,water accumulation begins to occur. The cumulative infiltration of soil ultimately depends on the saturated permeability of the soil. Comparing the calculation results of the four soils with the results obtained by the finite element method,the relative deviations are less than 5%,which verifies the reliability of the model.