In coastal areas or at river mouths, the foundations of structures such as bridge piers are subject to currents that can erode the soil around the piles. This scour can weaken or even destabilize structures. Until now, work has focused mainly on non-cohesive bottoms made of sand or gravel. However, sea or river beds often also contain fine particles (such as clay or silt) that make the soil cohesive. However, scour in the vicinity of structural foundations in the presence of cohesive sediments has been little studied (Qin et al., 2024; Zaidan et al., 2024). The proposed topic concerns erosion in the vicinity of a pile founded in cohesive soil subjected to current-type hydrodynamic forcing. The approach will be based on physical modeling using flume, combined with state-of-the-art instrumentation available in the laboratory (acoustic profiler for measuring velocity profiles, bathymetry probe, laser granulometer,... (Auzerais et al., 2016; Vah et al., 2022). The geotechnical characteristics of the materials constituting the soil will be determined, and soil erodibility will be estimated experimentally using a specific device. The proposed PhD will improve our knowledge of the physical processes driving scour in the vicinity of a pile in the presence of cohesive sediments, and the estimation of maximum erosion depths. In particular, the results will be used to test and improve existing models.

The work carried out in the framework of this PhD will enable innovative results to be obtained at national and international level, results that can be promoted through presentations at national and international conferences, as well as in international journals. This work fits in perfectly with the research themes of the Civil Engineering, Composites, Coastal Environment axis of the LOMC laboratory, UMR 6294 CNRS. It is also fully in line with the research themes of the CNRS 3730 SCALE Research Federation.