黄土浅层降雨入渗规律研究

目的]探讨黄土浅层降雨入渗规律,为研究降雨黄土滑坡机理提供理论参考。方法]以陕西省延安市大路沟滑坡为例,在不同深度裂缝处与非裂缝处布置监测仪器,结合数值模拟手段分析入渗规律。结果](1)研究区浅层地表通过降雨入渗补给,蒸发排泄。降雨对土体含水量的影响主要体现在土体含水量对降雨的响应时间和响应程度上,存在一定的滞后性,并且随着深度的增加滞后性越明显,蒸发排泄对土体含水量的影响表现在土体的深度和受光面积上,土体的深度越大,土体体积含水量受到蒸发作用影响越小。(2)黄土浅层土体含水量对降雨十分敏感,当降雨量3mm/d时,黄土浅层地表土体含水量基本不受降雨的影响,当3mm/d降雨量40mm/d时,土体含水量随雨水的入渗而变化,并且含水量的变化与降雨量大小成正相关。结论]由模拟不同工况下雨水入渗过程显示,在雨水入渗过程中,浅层裂缝对降雨入渗深度影响很小,并且研究区黄土入渗深度有限。

Regularities of Rainfall Infiltration in Shallow Loess

Objective] To explore the regularities of rainfall infiltration in shallow loess, and to provide reference for studying the mechanism of loess landslide caused by rainfall.Methods] One monitoring site was set up in Dalu Dicth, Shaanxi Province by arranging the monitoring instrument both in cracks and no-cracks at different depths. The observed results were dealt with numerical simulation to analyze the regularities of rainfall infiltration.Results] (1) Soil moisture was recharged by rainfall and was drained away through evaporation in the area. The main affect of rainfall on water content was the tempo-spatial responses to the rainfall. There had a hysteresis for temporal response, which was more obvious with the increase of the depth. The effect of evaporation on soil water content was influenced by the depth and the exposed area of soil. The greater the depth of soil was, the smaller the effect would be. (2) The soil water content was very sensitive to rainfall, e.g., when precipitation was less than 3 mm/d, the rainfall almost had no effects on the water content of soil, however, when precipitation was 3~40 mm/d, the rainfall was observed having positive effect on soil water content.Conclusion] The infiltration process simulation under different conditions showed that the effect of crack was little, and also the infiltration depth of loess in study area was limited.