植被发育斜坡根土间隙降雨入渗研究

摘要

Based on CT original data of soil columns,a three-dimensional distribution pattern of grass roots in well vegetated slope was reconstructed in this research by Volview software for visual recognition of root formation;Navier-Stokes equation was applied to build a physical concept model of root-soil interstices,to analyze the lateral speed of pore flow through interstices of soil;Lattice Boltzmann method was combined with Matlab programming to realize macroscopic simulation of slope seepage field.In order to investigate the behavior of root-soil interstice towards rainfall infiltration,several methods were combined to comprehensively examine the application of root-soil interstices developed in well vegetated slope to infiltration.Results showed that (1) CT scanning technology in connection with Volview software could be used for acquisition of interior formation of slope grass roots,laying a solid foundation for study on slope flow;(2) lateral porous flow in root-soil interstices had the maximum velocity at the center line,1.5 times of average speed;(3) As a method based on the fluid discrete particle,Lattice Boltzmann Method could be well applied to simulation of subsurface flow;(4) The vertical interflow rate inside root-soil interstices gradually decreased with increases in depth.The seepage in root-soil interstices mainly depended on the state of connected soil interstices and channels,and flow rate reduced to zero at a depth of about 30cm below.In this research it found that,by proper combination of the aforesaid methods,the existence of root-soil interstices in a well vegetated slope considerably contributed to rainfall infiltration and it provided an insight for slope seepage research.%基于土柱CT扫描数据,运用Volview软件重构土体三维图及根系分布图,精确了解土体根系分布情况;应用Navier-Stokes方程计算根土间隙物理概念模型,分析横向间隙流速分布情况;采用格子Boltzmann方法,并结合Matlab程序,实现渗流场细观模拟.为研究根土间隙在土体降雨人渗过程中的作用,综合以上多种方法,深入并全面分析根土间隙在植被发育斜坡降雨入渗过程中的作用.结果表明,(1) CT扫描技术结合Volview软件能够进行土柱三维重建,从而获取根系在土体分布实际情况,为研究根土间隙导流奠定基础;(2)横向根土间隙流速分布情况,中心线位置流速最大,为平均速度的1.5倍;(3)格子Boltzmann方法作为一种基于流体离散粒子的计算方法,能够结合编程软件进行土体渗流细观模拟;(4)随着深度的增加,竖向根土间隙渗流速度逐渐降低,其渗流作用主要依赖于一些连通性好的间隙通道,且流速在30 cm左右深度降低为零.以上各分析手段可有效评估根土间隙对植被发育斜坡在降雨入渗过程中的贡献,并深入分析植被发育斜坡根土间隙降雨入渗机理.