| 摘 要： |
Vegetation is widely recognized as a key factor controlling the occurrence of shallow landslides in vegetation-covered areas. In such areas, the root system plays a critical role both in enhancing root-soil mechanical properties and in changing soil hydrological properties. However, owing to its complexity and nonuniformity, the root system is always neglected or simplified in existing infiltration process models, making it difficult for such models to reflect the influence of root systems on shallow landslides. Considering the shallow landslide cluster that happened in Mengdong (Yunnan Province, Southwest China) in 2018, this study quantitatively investigated the root distribution and obtained the prevailing physical and hydraulic properties through density tests, shear strength tests, and saturated seepage tests. Field investigation indicated that the root system distribution obeys an exponentially decayed polynomial model. In the entire profile, the maximum root area density was 0.145 mm(2) cm(-2) at depth of 20-40 cm, which comprised 483 roots, and 80% of the roots were distributed above the slip surface. Laboratory test results indicated that root-soil above the slip surface had lower density (minimum density: 1.04 g cm(-3)) and higher porosity (maximum porosity: 61.23%) than soil below, which induced permeability 10-17 times higher above the slip surface. A potential relationship was found between slip surface location and root system distribution. Differences in root distribution and resultant changes in the hydrological properties of soil might reduce slope stability during extreme rainfall, which could induce shallow landslides. This research could be used as reference for slope stability and hydraulic process analysis in forested areas. |
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