宽级配砾石土中降雨入渗的优先流模型

发布时间：2018-09-06 13:31

【摘要】：宽级配砾石土的级配较宽,孔隙尺度跨越几个数量级,降雨入渗易形成空间上的不均匀入渗,即优先流入渗。基于孔隙结构的分形特征,定量研究降雨在宽级配砾石土中的入渗规律。根据多孔介质分形理论及HagenPoiseulle方程,水在不同尺度的孔隙管道内入渗率的量级不同,将土体的孔隙部分划分为2个区域—基质区和优先流区,这2个区域所占的比例随雨强的变化而变化。基质区内各孔隙管道的入渗率均达到其最大的入渗率,但各不相同,孔隙管道的直径量级小,入渗率量级小,优先流区各孔隙管道的入渗率相同且均未达到其最大入渗率,孔隙管道直径量级大,入渗率的量级远大于基质区,据此特征从理论上推导了降雨在土体不同孔隙区域内的入渗量和入渗率的表达式;基于此研究了基质区和优先流区的面积在孔隙中所占比例随雨强的变化特征及相应入渗量和入渗率的变化特征。结果表明:降雨在土体中的入渗呈现出优先流区高速入渗,基质区入渗相对缓慢的特点;随着雨强的增大,优先流区域的入渗率也随之增大。降雨入渗优先流现象产生的根本原因是土体多尺度的孔隙结构和无压力的自由入渗边界2个因素,其大小和分布受到土的饱和渗透系数和降雨强度的影响。从孔隙结构的角度解释了降雨入渗优先流的产生机制。
[Abstract]:The gradation of the grained gravel soil is wider, the pore scale spans several orders of magnitude, and the rainfall infiltration is easy to form inhomogeneous infiltration in space, that is, preferential inflow infiltration. Based on the fractal characteristics of pore structure, the infiltration law of rainfall in gravel-soil with wide gradation was studied quantitatively. According to the fractal theory of porous media and HagenPoiseulle equation, the water infiltration rate in different scale pore pipes is different. The pore part of soil is divided into two regions-matrix region and preferential flow zone. The proportion of these two regions varies with the change of rain intensity. The infiltration rate of each pore pipe in the matrix area is the highest, but it is different. The diameter of the pore pipe is small, the infiltration rate of each pore pipe in the preferential flow area is the same and the maximum infiltration rate is not reached. The diameter of pore pipe is large, and the infiltration rate is much larger than that of matrix region. According to the characteristics, the expressions of infiltration amount and infiltration rate of rainfall in different pore regions of soil are deduced theoretically. Based on this, the variation characteristics of the proportion of matrix area and priority flow area in pore with rain intensity and the corresponding infiltration rate and infiltration rate are studied. The results show that the infiltration of rainfall in soil presents the characteristics of high speed infiltration in preferential flow area and relatively slow infiltration in matrix area, and the infiltration rate of preferential flow area increases with the increase of rainfall intensity. The primary causes of preferential flow of rainfall infiltration are the multi-scale pore structure of soil and the free infiltration boundary without pressure. The size and distribution of the two factors are affected by the saturation permeability coefficient and rainfall intensity of the soil. The mechanism of preferential flow of rainfall infiltration is explained from the point of view of pore structure.
【作者单位】：中国科学院山地灾害与地表过程重点实验室;中国科学院水利部成都山地灾害与环境研究所;中国科学院青藏高原地球科学卓越创新中心;中国科学院大学;河北地质大学勘查技术与工程学院;云南农业大学水利学院;
【基金】：国家重点基础研究发展计划资助项目(2013CB733201) 中科院重点部署项目资助(KZZD-EW-05-01);中科院百人计划资助项目(苏立君) 国家自然科学基金资助项目(51278397)
【分类号】：TU43;TV139.1

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