降雨作用下红土型坡面径流特性与土壤侵蚀的关系研究

摘要

In this research,it revealed the relationship between the hydrodynamic characteristics of Yunnan laterite slope runoff,dry density,erosion modulus of slope surface and shear stress of slope runoff during rainfall.This was completed specifically for Yunnan laterite slope with a certain rainfall intensity and slope inclination by our proposed research approach by using artificially-mimic-rainfall-model experiments and soil tests in connection with theoretical analysis.The results showed:(1) the average velocity of runoff on slope increased gradually in the early stage of runoff duration and then tended to be stable later on.The average velocity of slope runoff increased significantly with the increase of dry density of laterite.The relationship between the average velocity and unite discharge of runoff could be expressed as a power function:R2 =0.996.(2) Similarly,the average water depth of runoff increased gradually in the early stage of the runoff duration and then tended to be stable.Furthermore,the average water depth of runoff were expected to greater with a larger dry density.The relationship between the average water depth and the unite discharge of runoff could be also expressed as a power function:R2 =0.996.(3) Runoff stayed in the pattern of rapid laminar flow under experimental conditions.(4) In case of the certain experimental conditions and some of dry densities,the erosion modulus of laterite slope increased with runoff shear stress increment,and a linear relationship could be observed between the erosion modulus and the runoff shear stress.With the value of dry density were given to 1.0,1.1,1.2,1.3,1.4 g/cm3,the R2 ranged from minimum 0.816 to maximum 0.945,and the critical shear stress of laterite slope was 0.482,0.510,0.556,0.586,0.656 Pa respectively.The behaviors of slope runoff was controlled by various factors.The erosion modulus of slope and the relevant critical shear stress of slope runoff was closely related to the characteristics of runoff and soil.%针对云南红土型坡面和一定的雨强、坡度,运用人工模拟降雨水槽模型试验、土工试验及相关理论分析相结合的研究方法,揭示降雨作用下云南红土型坡面径流的水动力学特性及红土干密度、坡面侵蚀模数与坡面径流剪切力之间的关系.结果表明:(1)坡面径流平均流速随坡面径流历时呈先逐渐增大后趋于稳定的变化趋势,且坡面径流的平均流速随红土干密度的增大而显著增加.坡面径流平均流速与单宽流量呈幂函数关系(R2=0.996).(2)坡面径流平均水深随径流历时也呈先上升而后趋于稳定的变化过程,且干密度越大,平均径流水深也越大,平均径流水深与单宽流量也呈幂函数关系(R2=0.996).(3)在试验条件下,坡面径流流态属层流急流流态.(4)在试验条件和干密度一定的条件下,玻面侵蚀模数随径流剪切力的增大而增大,二者之间呈线性关系,当干密度为1.0,1.1,1.2,1.3,1.4 g/cm3时,R2最小为0.816,最大为0.945;坡面红土的临界剪切力分别为0.482,0.510,0.556,0.586,0.656 Pa.坡面径流特性受多种因素的联合作用,坡面侵蚀模数及红土临界剪切力与坡面径流特性和土壤自身特性密切相关.