降雨条件下云南红土理化特性对坡面侵蚀的影响研究

Impact of the Physical Chemical Properties and the Erosion on the Slope of the Yunnan Laterite under Rainfall Conditions

针对不同初始状态的云南红土,在一定雨强、坡度、坡长条件下,研究红土理化特性对坡面侵蚀的影响。采用人工模拟降雨方法进行试验研究,运用Excel分析试验数据。结果表明:(1)红土颗粒组成中黏粒含量对降雨作用下的红土坡面侵蚀影响显著,当黏粒含量增加8.1%时,其侵蚀模数则减小25.8g/(m^2·h);(2)红土初始含水率偏离最优含水率越远,红土侵蚀模数越大。当红土初始含水率从接近最优含水率的24.6%增加到36.5%时,侵蚀模数从110.4g/(m^2·h)增加到121.3g/(m^2·h);(3)在初始干密度为1.0,1.1,1.2,1.3,1.4g/cm^3条件下,红土侵蚀模数呈先增大后减小的二次曲线变化趋势(R^2=0.927)。初始干密度在1.1~1.2g/cm^3之间,红土侵蚀模数存在极大值[126g/(m^2·h)];(4)降雨作用使坡面红土铁铝氧化物含量减少,接近坡脚处Fe_2O_3含量从初始状态的8.591%减小到8.143%,Al_2O_3含量从初始状态的22.242%减小到20.967%;而坡内红土铁铝氧化物含量则随深度增加,坡体中段坡内的Fe_2O_3含量增加0.407%,Al_2O_3含量增加0.861%。降雨作用改变了红土理化特性,而红土理化特性的变化会对红土坡面侵蚀产生显著影响。

For a certain initial state of the Yunnan laterite and a certain slope, slope length,the effect of the physical and chemical properties of the Yunnan laterite on the erosion on slope under the f rainfall conditions is studied by using artificial simulated rainfall test method. The results indicated that：（1） The content of clay particles in the group of laterite is the most significant for slope erosion under rainfall effect. When laterite content increased about 8.1%, the erosion modulus increased by 25.8 g/（m^2.h）;（2） The more the initial water content of laterite is deviated from the optimum water content, the erosion modulus of laterite became bigger. When the initial water content of laterite increased from 24.6% near the optimum water content to 30.5%, the erosion modulus increased from 110.4g/（m^2.h）to 121.3g/（m^2.h）. （3） Under the conditions of initial dry density 1.0g/cm^3、1.1g/cm^3、1.2g/cm^3、1.3g/cm^3、1.4g/cm^3, the laterite erosion modulus was the change trend of the two curves which firstly increased and then decreased. At the initial dry density of 1.2g/cm^3, the erosion modulus reached a maximum of about126 g/（m^2.h）.（4）The content of Fe2O3 and Al2O3 decreased by the effect of rainfall on the slope. The content of Fe2O3 decreased from 8.143% in the initial state to 8.591% and the content of Al2O3 decreased from 22.242% in the initial state to 20.967% on the surface of the slope foot. The content of Fe2O3 and Al2O3increased with depth in the slope. The content of Fe2O3 increased by 0.407%, and the content of Al2O3 increased by 0.861%. The changes of iron and aluminum oxide content will lead to the changes in the resistance to erosion of laterite .