中文摘要：

通过自主研制的非饱和土直渗仪,对高为15cm、直径为12.5cm的圆柱形黄土试样进行降雨强度分别为16mm/h、50mm/h、70mm/h的渗透模拟试验,分析降水入渗深度、径流、富集量等与时间的对应关系,探究降水-黄土间的作用模式。得到实验结果：①不同雨强作用下,降水入渗锋面均呈漏斗状,凹面向下,均匀推进;②试验后试样含水率均超过液限,但随雨强增大含水率相应减小;③雨强16mm/h时无径流产生,雨强50mm/h、70mm/h时径流分别在试验开始29min和14min时形成;④降水入渗具有阶段性,雨强16mm/h,可分为快速下渗、缓慢下渗和匀速下渗三个阶段;雨强50mm/h、70mm/h,水开始入渗速率与土自身吸水能力有关,待上覆土饱和,水不仅受重力还受水驱动力的作用,入渗速度加快,最后稳定。获得结论包括：（1）雨强越大,水受重力和水力梯度作用越大,水下渗速度越快,充填孔隙的水就越少;（2）在雨强大于土体吸水能力的一定范围内,雨水补给量、径流量、下渗量以及充填量之间随降雨历时、入渗深度、孔隙度变化等因素出现相互制约、相互促进的关系;（3）试样完成渗流后,土体内形成稳定流,富集量与时间呈线性关系。

英文摘要：

In order to study the mode and action of water and soil and explore the mechanism of loess disaster, in this work a vertical permeameter instrument on unsaturated soil is designed,the seepage test is implemented under the rainfall intensity and irrigation intensity of 16mm / h,50mm / h and 70mm / h,respectively,for loess specimen（ 15cm high and 12. 5cm in diameter）. Correlation among displacement of infiltration front and times（ seepage velocity）,runoff volume and times（ runoff velocity）,seepage volume and times（ enrichment velocity） are quantitatively analyzed. The test results show that ① the infiltration front is choanoid. ② Specimens＇ moisture is over the liquid limit and saturation after the seepage test,decreases with the increasing rainfall intensity or irrigation intensity,showing that the increasing intensity,and the water loaded under two forces（ gravity and hydraulic gradient） flows faster,and fills the pores few. ③ Valued rainfall intensity of 16mm / h,is not runoff,and 50mm / h,70mm / h,runoff is apparent at the test beginning 29 min and 14 min, water absorbing ability of loess is 16mm / h to 50mm / h（ when the rainfall intensity just equal to seepage amount）. ④ Under rainfall intensity of 16mm / h,infiltration process consists of 3 stages： fast,slow and stable. Seepage velocity was 0. 31cm / min,0. 16cm / min,0. 02cm / min. Under rainfall intensity of 50mm / h and 70mm / h,seepage velocity are 0. 42cm / min,0. 68cm / min,0. 036cm / min and 0. 36cm / min,0. 95cm / min,0. 2cm / min. Among those data,the seepage velocity at the second stage is the largest,indicating that it exists coupling relationship within some scope of rainfall intensity over the absorbing ability,among rainfall, runoff,seepage,infiltration and filling. ⑤ For irrigation situation,water infiltration flows down all over, specimen get saturated where the infiltration front walks,and it is relatively obvious with the increasing water head. ⑥ Specimen is saturated after seepage test,the stable see