Numerical Investigation of Impulse Waves Impacting Dams

Impulse waves are generated by landslides, rockfalls and iceberg calving in water bodies such as lakes and reservoirs. These waves represent a persistent danger for dams, e.g. in the 1963 Vajont disaster an impulse wave impacted and overtopped the Vajont dam causing approximately 2000 causalities. Unfortunately, an accurate prediction of the effects of tsunamis on dams, e.g. pressures and forces, is still subject to large uncertainties and 3D effects are typically neglected. The present study relies on the numerical modelling of impulse waves impacting dams with the toolbox solids4foam. To this end, a total of 72 2D tests involving a range of wave conditions and dams of different inclinations have been conducted. A new empirical equation to predict the run-up height is suggested, showing a good agreement with available laboratory measurements. The resulting wave forces on dams agreed with an available empirical method, further extending its validation range. Novel insight in the 3D effects is given based on 4 simulations with straight and arch dams impacted normal or at an angle of 30 degrees. Both the dam curvature and asymmetrical wave impact resulted in up to 32% larger run-up heights at the dam flanks than in the centre. Such findings may support tsunami hazard assessment in reservoirs and are also relevant for a range of coastal designs, e.g. oil and gas rigs, breakwaters and flood protection systems.