降雨作用下云南省红土抗剪强度与坡面侵蚀模数的关系

目的]揭示降雨作用下云南省红土的含水率、干密度、抗剪强度、坡面侵蚀模数之间的关系,为进一步研究云南省红土的侵蚀机理提供理论依据。方法]运用人工模拟降雨及土槽模型试验、土工试验及相关理论分析相结合的研究方法。结果](1)研究区红土黏聚力随含水率的变化呈二次曲线关系,且在最优含水率附近存在极大值。红土内摩擦角随含水率的变化接近于线性关系,且随含水率的增大而减小。当干密度为1.0,1.1,1.2,1.3,1.4g/cm3时,黏聚力与含水率的相关系数R2最小为0.754,最大为0.934;内摩擦角与含水率的相关系数R2最小为0.944,最大为0.996。(2)红土黏聚力和内摩擦角随干密度的变化接近于线性关系;当含水率一定时,二者随干密度增大呈增加的趋势。(3)在试验含水率条件下,红土抗剪强度随含水率的增加而减小,当含水率超过最优含水率后减小的幅度尤为明显;抗剪强度随干密度的增加而增大。(4)降雨结束后,不同干密度的红土坡面侵蚀模数与红土抗剪强度呈二次曲线关系,相关系数R2达0.988。结论]坡面红土雨后抗剪强度与坡面侵蚀模数之间存在较好的相关关系,可用坡面红土的雨后抗剪强度估算坡面侵蚀量。

Relationship Between Shear Strength and Slope Erosion Modulus of Laterite Under Rainfall Conditions in Yunnan Province

Objective] The relationship between water content, dry density, shear strength and erosion modulus of laterite in Yunnan Privince, was studied under rainfall condition, in order to provide a theoretical basis for further studies on the erosion mechanism of laterite. Methods] The methods included artificial simulated rainfall and soil trough model experiments, soil test and relative theoretical analysis. Results] (1) The relation of the cohesion of laterite with water content showed a quadratic curve relation. Near the optimum water content, the maximum cohesion occurred. The internal friction angle was approximate to the linear relationship with the water content change, and the internal friction angle decreased with increasing water content. Under the conditions of initial dry density 1.0, 1.1, 1.2, 1.3, 1.4 g/cm³, the correlation coefficient(R²) between cohesion and water content ranged from a minimum of 0.754 to a maximum of 0.934, and the R² between internal friction angle and water content ranges from the minimum of 0.944 to the maximum of 0.996. (2) The relation between cohesion and internal friction angle were close to linear relationship with the change of dry density. When the water content was constant, the curve of the relationship between cohesion and internal friction angle with the change of dry density had a certain variation, and the cohesion and internal friction angle increase with the increasing of dry density. (3) The shear strength decreased with increasing water content, and the amplitude was especially obvious when the water content was higher than the optimum water content. The shear strength increased with increasing dry density. (4) By the end of the rain, for laterite with different dry densities, the relationship between the slope erosion modulus and the shear strength showed a quadratic curve relation, and the correlation coefficient (R²) can be up to 0.988. Conclusion] There is good correlation between the shear strength and the slope erosion modulus, and estimating the amount of the slope erosion with the shear strength of laterite after rain is possible.