Riverbed erosion due to flooding events presents one of the main challenges for transportation infrastructure. During extreme weather events, the risk of flood-induced structural failures is increased substantially due to scour at the foundations of bridges. This is particularly evident for the case of energetic flow structures, which accelerate erosion processes of downstream soil material and often leads to damage of scour protection systems (Valyrakis et al., 2013). This study aims to assess failure risk of scour protection systems and erosion of adjacent areas and provide and understanding of the evolution of critical flows and scour processes. This is accomplished with the application of two different sensing instruments to (a) monitor the probability of entrainment of an instrumented particle appropriately positioned on the surface of a protective layers (Al-Obaidi et al., 2020) and (b) provide real-time assessment of scour evolution on the riverbed adjacent to the bridge foundation using a new electromagnetic sensor (Michalis et al., 2019). Flume experimental testing under well controlled flow conditions is carried out to evaluate the change in entrainment frequencies based on the instrumented particle response positioned downstream a physical model of a bridge. At the location of the bridge pier the EM sensor is installed to record the evolution of riverbed changes. Flow profiles are also continuously obtained at specific space intervals downstream the simulated bridge pier with an Acoustic Doppler velocimetry (ADV). The obtained dataset is analysed to assess the energetic turbulent flow mechanisms that accelerate scour driving forces resulting in excessive erosion and damage of protective layers (Pähtz et al., 2020).
References
Al-Obaidi, K.; Xu, Y.; Valyrakis, M. The Design and Calibration of Instrumented Particles for Assessing Water Infrastructure Hazards, J. Sens. Actuator Netw. 2020, 9(3), 1-18, https://doi.org/10.3390/jsan814323.
Michalis, P.; Tarantino, A.; Tachtatzis, C.; Judd, M.D. Wireless monitoring of scour and re-deposited sediment evolution at bridge foundations based on soil electromagnetic properties, Smart Materials and Structures. 2015, 24(12), pp. 125029.
Pähtz, T. ; Clark, A. H.; Valyrakis, M.; Duran, O. The Physics of Sediment Transport Initiation, Cessation, and Entrainment Across Aeolian and Fluvial Environments. Rev. Geophys. 2020, 58(1), 1-58, doi: 10.1029/2019RG000679.
Valyrakis, M.; Diplas, P.; Dancey, C.L. Entrainment of coarse particles in turbulent flows: An energy approach. J. Geophys. Res. Earth Surf. 2013, 118, 42-53, doi:10.1029/2012JF00235.
ACKNOWLEDGMENTS
Dr. Panagiotis Michalis research is co-financed by Greece and the European Union (European Social FundESF) through the Operational Programme «Human Resources Development, Education and 4 Lifelong Learning» in the context of the project “Reinforcement of Postdoctoral Researchers - 2nd Cycle” (MIS-5033021), implemented by the State Scholarships Foundation (ΙΚΥ).
