Plant roots positively and negatively contribute to hillslope stability by the perspective of soil strength and water flow infiltration improvement. To further examine the controversy, this work addresses the six root architecture types on the rainfall threshold for slope stability by tests of saturated conductivity and shear strength of the root-soil composite. An infinite slope model and a 1D flow model combine to obtain the rainfall intensity-duration threshold of slope failure. The results reveal that the saturated hydraulic conductivity of root-soil composite is 1 to 4.23 times of bare soil, which increases as the length density, volume density, and volume fractal dimension of plant roots. Furthermore, plant roots can enhance the cohesion and angle of internal friction by 35.19–81.79% and 12.92–42.36%, respectively. Finally, the R-type and V-type roots have the most effective root architecture for hillslope stability. In the process of afforestation, H-type may be suitable for areas with soft slope, while V-type and R-type may be suitable for steep slopes. The results of this work present an interesting study on the interaction of plant roots on slope stability, which is worthy of further study in the future.

中文翻译：

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根系结构对边坡稳定性降雨阈值的影响：饱和导水率和根土复合材料强度的变化

从土壤强度和水流入渗改善的角度来看，植物根系对山坡稳定性有积极和消极的贡献。为了进一步研究争议，这项工作通过测试根 - 土壤复合材料的饱和电导率和剪切强度，解决了斜坡稳定性降雨阈值的六种根结构类型。无限边坡模型和一维流模型相结合，得到边坡破坏的降雨强度-持续时间阈值。结果表明，根土复合体的饱和导水率为裸土的1～4.23倍，且随着植物根系的长度密度、体积密度和体积分形维数的增加而增加。此外，植物根系可以分别提高内摩擦力和内聚力 35.19-81.79% 和 12.92-42.36%。最后，R 型和 V 型根系具有最有效的山坡稳定性根系结构。在造林过程中，H型可能适用于坡度较软的地区，而V型和R型可能适用于陡坡。这项工作的结果对植物根系对边坡稳定性的相互作用进行了有趣的研究，值得在未来进一步研究。