Flow susceptibility of heterogeneous marly formations. Implications for torrent hazard control in the Barcelonnette basin (Alpes-de-Haute-Provence, France)
Résumé
Earthflows, debris avalanches and debris flows occurring in black marls in Southeast France present differentiated morphological characteristics and velocities. The rheological response of these remoulded fine-grained flow-like landslide deposits have been investigated using several techniques (parallel-plate rheometry, coaxial rheometry, slump tests and inclined plane tests). This contribution shows that rheological characteristics can be useful in establishing the transformation process of the materials into flow-like phenomena and identifying the natural mixture of basic formations which present the weakest yield stress and viscosity. Results show that the simple shear behaviour of all these natural flows clearly distinguishes the type of movement, in particular for earthflow and debris flow. Furthermore, some proportion mixtures present the highest mobility properties, and thus the highest susceptibility for transformation into high-speed flow-like phenomena. Results may be useful for identifying potential source zones in muddy flow-like landslide prone areas.
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