Author(s): Michael Sturm, Bernhard Gems, Markus Aufleger, Bruno Mazzorana, Maria Papathoma-Köhle, Sven Fuchs
Linked Author(s): Michael Sturm
Keywords: Bed-load transport, physical scale model, impact force, fluviatile hazards, vulnerability
Abstract:
Flood events in mountain streams mobilize and transport large amounts of sediment and often lead to sediment depositions on densely populated alluvial fans. The impacts of these fluviatile hazard processes potentially lead to a substantial damage of buildings, infrastructure facilities, etc. The work presented deals with experimental measurements and calculations of impact forces on obstacles induced by fluviatile sediment transport processes. A physical scale model, consisting of a force plate in a homogeneous flume to measure the fluviatile impacts, was set up at the scale 1:30. Influence of different parameters on the impact forces, such as channel gradient, flow discharge, grain size distribution of the supplied sediment, concentration of bed-load within the flow mixture, the incident flow angle to the object and different dimensions of the object were tested. Correlations of measured flow depths and velocities with the impact forces were further analysed. A 3d-numerical model (FLOW-3D) of the experimental flume was built up and numerical analyses were executed to validate the measured data under clear water conditions. Thereby the suitability of Froude similarity to scale the measurement data into prototype dimensions was verified. The results show that in the majority of experimental scenarios, the sediment input leads to a decrease of the impact forces due to the lateral deflection of the flow mixture in front of the plate, induced by the sediment deposition. However, the applicability of a 3d-numerical modelling approach to calculate impact forces of fluviatile hazards on obstacles is verified for clear water conditions. The study provides valuable information for further and more complex experiments on the fluviatile hazard impacts on buildings, associated analysis of consequences for buildings stability and serviceability, and vulnerability analysis of buildings exposed to fluviatile hazard events. (2620, 65, 298)
Year: 2017