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MOuntain zone Natural HAzards: physics and mechanics of gravitational flows – MONHA

Submission summary

Gravitational flows occurring in mountainous areas represent a major concern for public authorities, populations, and local economy. The objective of MONHA project is to improve the scientific bases of engineering practices used to defend against these natural hazards. Specific consideration will be given to snow avalanches and debris flows, whether generated by natural processes of by failure of earth dams on high slopes. However, the project addresses fundamental research issues, and its results should thus be relevant to most other sub-aerial gravitational flows (lahars, rock avalanches,…). Our ambition is to obtain fine descriptions of the physical and mechanical processes involved in these phenomena. More specifically, the effort will be devoted to the understanding of several key issues related to the rheological behavior of the involved geomaterials: (i) role of interstitial fluid, (ii) mechanical behavior in the vicinity of phase transitions (solid-fluid and fluid-solid), (iii) nature and influence of non-stationary processes. The current lack of knowledge concerning these issues represents an impediment to the accurate modeling of gravitational flows. Four complementary tasks, all dealing with these issues, are planed: Task 1. Influence of seepage on gravitational instabilities and the solid-fluid transition. Task 2. Influence of rate and state-dependent effects and of distance from threshold on gravitational instabilities and the solid-fluid transition. Task 3. Influence of compositional heterogeneities on gravitational flow propagation. Task 4. Nature of the processes active during the fluid-solid transition (flow stoppage). Work in these tasks will be mainly based on the use of model materials and of original, small-scale laboratory experiments specially designed to provide good insight into the elementary processes involved. The experimental setups already exist and have been partially validated by preliminary tests. Hence, successful outcomes during the time of the project appear reasonably warranted. Scaling issues related to these experiments will be systematically considered. In particular, Cemagref broad implication in field experiments and observations will allow to compare the results obtained in the laboratory to full-scale data. Hence, though fundamental, MONHA project is expected to effectively contribute to the improvement of risk analysis and mitigation in vulnerable mountainous areas.

Project coordination

Guillaume CHAMBON (Organisme de recherche)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Help of the ANR 140,000 euros
Beginning and duration of the scientific project: - 36 Months

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