Assessing the mass flux from a breached model dam with laser imaging and Large‐Scale PIV

Abstract

The flow originated by a dam failure is a complex 3D two-phase flow thus the breaching process details can only be addressed with comprehensive and controlled laboratorial work. This study represents a contribution to achieve this goal and is based on laboratory tests on failure by overtopping of cohesive homogenous earthfill dams. These were performed in a medium-scale facility at the Portuguese National Laboratory for Civil Engineering under hydraulic and geotechnical controlled conditions. The main goals were to develop novel estimates of the breach effluent hydrographs and to advance the state-of-the-art in the relation between the flow hydrodynamics and the breach morphologic evolution. The novel estimates of the breach effluent flow showed good agreement with traditional ones, hence indicating the need to study in the detail the breaching process. The latter demonstrated that the breach effluent flow presents a gradual increase, rather than sudden, in response to the occurrence of soil mass detachments. Finally, the results herein achieved were only possible due to the use of recent instrumentation, as well as to the adoption of innovative measuring methods and by extracting the goal variables through image post-processing techniques.