积水和降雨下非饱和重塑黄土水分入渗模拟

Simulation of Water Movement in Unsaturated Remolded Loess Under Ponding Infiltration and Rainfall Infiltration

摘要:

为合理预测积水和降雨情况下非饱和重塑黄土水分迁移过程，在已有模型基础上，提出了能合理考虑浸润锋处吸力作用和水分剖面形状的改进模型，并给出了该模型计算方法以及求解Richard方程数值方法所需渗透参数的可靠确定方法.研究结果表明：与已有模型相比，改进模型能更准确地预测室内一维非饱和重塑黄土土柱积水入渗试验中浸润锋迁移过程和各测点水分变化过程；采用改进浸润锋前进法获得的非饱和渗透系数函数，比采用根据室内饱和渗透试验和持水曲线间接获得的参数所得预测结果更为准确；降雨分析中，改进模型得到径流发生后的水分剖面基本接近于数值方法分析结果，特别是在试样干密度比较大的情况.

关键词:非饱和黄土; 降雨; 入渗; Green-Ampt修正模型; 浸润锋前进法

Abstract:

In order to simulate the water movement in the unsaturated remolded loess under ponding and rainfall conditions, an improved infiltration model based on the modified Green-Ampt model and the model proposed by Wang Wenyan et al., which can reasonably consider the effect of suction at wetting front and the water content profile, was proposed. The reliable method for determining the parameters needed in the model based on the modified GreenAmpt model and the numerical method for solving Richard’s equations was also recommended. The research results show that the improved model can more accurately predict the movement of wetting front and the water content change at measured points in the onedimensional ponding infiltration test, compared with the modified Green-Ampt model and the model proposed by Wang Wenyan et al. When the unsaturated hydraulic conductivity function was determined directly by the improved wetting front advancing method in the ponding infiltration test, the results are closer to the measured values compared with those parameters indirectly determined by the saturated permeability test and water retention curve. For rainfall infiltration, the water profile after runoff obtained by the improved model is similar to that obtained by the numerical method, especially for the soil with a higher dry density.

Key words:unsaturated loess; rainfall; infiltration; modified Green-Ampt model; wetting front advancing method