Experimental and numerical study on landslide dams breaching and the induced local morphological changes under different material composition
(2023) M.S. YALIN MEMORIAL COLLOQUIUM 2023 (YMC2023) — Location: Palermo, Italy (27.January.2023)
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- Landslide dams breaching and the induced morphological changes highly depend on the dam material composition. A bi-modal composition was observed in most of landslide dams’ material, but the influence of this material composition on the failure mode, breaching parameters and morphological changes is poorly understood. In this study, we experimentally investigate the landslide dams breaching process and its impact on local morphology by varying the material composition of both dam and movable bed. The considered bimodal material compositions consists of different percentages of coarse material (gravel) and fine material (sand). The breaching parameters including peak discharge and residual water level in the upstream reach are highly determined by the dam material composition, while the effect of movable bed material appears more complex. The final breach size, especially the breach depth, increases significantly with the increase of sand content in the dam material, while the effect of movable bed material on final breach size is relatively limited. We further find that stronger erosion and deposition are observed if a finer movable bed is considered, which complicated the dam breaching process and lead to the variation of peak discharge but to a similar final breach size. In addition, it was observed that the dam breach pattern is mainly controlled by the change of erosion rate and erosion surface gradient during the dam breaching. These two parameters are influenced by the deposition at the downstream dam toe, which further impacts the dam breach process. Uneven distributed deposition is observed on the downstream movable bed, and its depth as well as heterogeneity is intensified with the increase of sand content in both the dam and movable bed material. Furthermore, sandbars are observed if the materials with lower sand content are considered, and thus change the flow direction and lead to the formation of a meandering channel. This study improves our understanding of landslide dams breach and the induced morphological changes, with the aim of further helping hazard management.
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Yang, J., Soares Frazao, S., & Shi, Z. (2023). Experimental and numerical study on landslide dams breaching and the induced local morphological changes under different material composition. M.S. YALIN MEMORIAL COLLOQUIUM 2023 (YMC2023), Palermo, Italy. https://hdl.handle.net/2078.5/216578