Abstract
The simple-shear condition is closer to reality than the direct-shear condition for simulating the mechanical behavior of vegetated soil slope under shallow failure. However, study on simple-shear characteristics for vegetated slope is still insufficient, and there lacks intuitive comparison of characteristics between these two shear conditions. In this study, large-scale simple-shear and direct-shear experiments were conducted on soil permeated by roots of Amorpha fruticosa to investigate the shear strength and stiffness. The stress-displacement relationship of each sample was obtained and further normalized to unify the influence of root content. The results reveal that the direct-shear condition overestimates the shear strength of root-permeated soils (by 41%) and thus the estimation of slope stability based on the parameters of direct-shear condition is not conservative. Furthermore, the initial stiffness of root-permeated soil under simple-shear condition is 34% lower than that under direct-shear condition. The higher strength and stiffness under direct-shear condition are caused by the following reasons: the shear plane does not have the lowest strength, the shear area is decreasing, and the shear zone is thinner. The significant deformation (lower stiffness) revealed by the simple-shear condition facilitates the application of early warning for vegetated shallow landslides.
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Acknowledgments
The authors acknowledge the financial supports from the National Natural Science Foundation of China (Grant No. 41925030 and 4179043), the Second Tibetan Plateau Scientific Expedition and Research Program (STEP, Grant No. 2019QZKK0904), and the Natural Science Foundation of Shaanxi Province (2020JQ-041). Technical support from the Yanting Agro-ecological Experiment Station of Purple Soil of Chinese Academy of Sciences is also acknowledged.
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CHEN Jing-yi: Investigation, Formal Analysis, Visualization, Writing - original draft. CHEN Xiao-qing: Conceptualization, Funding Acquisition, Supervision. SONG Dong-ri: Resources, Methodology, Writing - review and editing. LV Ming: Formal Analysis, Methodology, Investigation. GUO Han-qing: Investigation, Data collection. SADEGHI Hamed: Writing - review and editing.
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Conflict of Interest: The coauthor of this article CHEN Xiao-qing is the editorial board member of Journal of Mountain Science. He was not involved in the journal’s review of, or decisions related to, this manuscript.
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Chen, Jy., Chen, Xq., Song, Dr. et al. Characteristics of root-permeated soil under simple-shear and direct-shear conditions. J. Mt. Sci. 20, 2422–2435 (2023). https://doi.org/10.1007/s11629-022-7722-x
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DOI: https://doi.org/10.1007/s11629-022-7722-x