Experimental field study on the fatigue and failure mechanisms of coastal chalk cliffs: Implementation of a multi-parameter monitoring system (Sainte-Marguerite-sur-Mer, France) - CLOSE Géosciences Rennes - Dynamique, Imagerie et Modélisation des Systèmes Environnementaux Accéder directement au contenu
Article Dans Une Revue Geomorphology Année : 2022

Experimental field study on the fatigue and failure mechanisms of coastal chalk cliffs: Implementation of a multi-parameter monitoring system (Sainte-Marguerite-sur-Mer, France)

Stéphane Costa
Olivier Maquaire
Robert Davidson
Laurent Longuevergne
Jérôme de La Bernardie
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Résumé

Between November 2018 and January 2020, a continuous multi-parameter survey, using nine types of sensors, was carried out on a coastal chalk cliff in Sainte-Marguerite-sur-Mer (Normandy, France) with the objective of gaining a deeper understanding of the forcing agents and processes that lead to cliff fatigue and failure. This paper will present the survey instrumentation, the results on the internal characteristics of the chalk massif, initial results (from November 2018 to March 2019) of the thermal subsurface behaviour along the cliff face, and the analyses of the observed cliff-top ground motion and the movement of existing fractures on the cliff face in relation to forcing agents. Our main results show that 1) the magnitude of cliff-top displacement on this coastal chalk cliff is consistent with prior studies conducted in different settings showing rather high displacement amplitudes (up to 50 μm in relatively calm conditions) likely to be related to chalk elasticity; 2) the displacement on existing fractures is partly controlled by the tidal amplitude, with a threshold response, but not only. Statistical analyses help the identification of other controls. The processing of the entire dataset from November 2018 to January 2020 with a combined analysis of multiple sensors output is expected to provide further insight on cliff fatigue and failure.

Domaines

Géomorphologie
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Dates et versions

insu-03636861 , version 1 (11-04-2022)

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Pauline Letortu, Nicolas Le Dantec, Emmanuel Augereau, Stéphane Costa, Olivier Maquaire, et al.. Experimental field study on the fatigue and failure mechanisms of coastal chalk cliffs: Implementation of a multi-parameter monitoring system (Sainte-Marguerite-sur-Mer, France). Geomorphology, 2022, 408, pp.108211. ⟨10.1016/j.geomorph.2022.108211⟩. ⟨insu-03636861⟩
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