雨强对工程堆积体侵蚀规律和细沟发育的影响

Effect of rainfall intensity on erosion and rill evolution of engineering piles

以陕西杨凌周边开发建设项目弃土堆积体表层土壤为试验材料，模拟野外最常见的散乱锥状堆积体的形成过程和堆置形态。在室内模拟降雨的条件下，设计了七组降雨强度（1．0、1．25、1．5、1．75、2．0、2．25、2．5mm／min），研究了雨强对物质组成为全土的锥状工程堆积体的产流产沙规律和细沟发育的影响。结果表明：①降雨强度对径流率和侵蚀速率的变化规律有着显著的影响，在不同的降雨条件下，径流率和侵蚀速率随时间的变化规律不同；②各雨强条件下，细沟长度、宽度和深度的变化趋势不同，其中细沟长度与侵蚀速率之间存在着显著的正相关关系；③在产流初期（0～10min），侵蚀速率随雨强的增大呈现出一条较为平缓的曲线，产流时间〉10min后，侵蚀速率随雨强的增大呈现出指数增大的趋势；④总侵蚀量与雨强之间存在着明显的指数关系。

Erosion of engineering piles is different from traditional slopes, owing to lacking organic matter, scat- ter material composition and special form. However existing studies are mainly focused on the tradition slopes or the short-slope piles,so that the erosion processes of the engineering deposits in the field can＇ t be studied accurately. As a result, studying the erosion processes of three-dimensional engineering piles with the same de- gree with that in the field is necessary. In this paper, in order to simulate the engineering piles, a self-made platform was used to pile the soil which is selected from the Yangling District in Shanxi Province. The rain sim- ulation experiments were conducted in the laboratory with seven kinds of rainfall intensities （ 1.0,1.25,1.5, 1.75,2.0,2.25,2.5mm/min）. Variations in erosion were studied experimentally,including volume of runoff, rate of erosion,and characteristics of the rill. Results show that both the rainfall intensity and the rill have sig- nificant impacts on the volume of runoff and the rate of erosion. The tendency of runoff and erosion is different from the rainfall intensity ; The length,width and depth of rills show different tendency in each rainfall test. The length of rill which has obvious relevance to the rate of erosion can represent the process of rill well. In the ini- tial runoff （1 -10min）,the rainfall intensity has a small influence on the rate of erosion. As the increase of rainfall intensity,the erosion rate shows a relatively smooth curve. When the runoff time is more than 10 mi- nutes, the erosion rate is affected by the rainfall intensity significantly, and the erosion rate shows an exponen- tial increasing trend with the increase of rainfall intensity. There is an obvious exponential relationship between the total amount of erosion and the rainfall intensity according to the experimental data.