Embankment dams are vulnerable to excess through-flow as well as overtopping. Downstream erosion protection is commonly provided against through-flow. In Norway erosion protection, comprising placed riprap on the downstream slope is required and considers overtopping in addition to excess leakage. The robustness of this structural system is dependent on the dam toe. Further, the dam toe is important for safe passage of seepage from under and through the dam, as well as along the abutments. Still, very limited research is available on this important feature. Additionally, the breaching mechanism of this embankment dam type has not been investigated to the fullest, and the current practice is to use breaching parameters that are derived without consideration of embankment dam type and material. The breaching parameters are required for estimating the flood resulting from dam breach, and thus ultimately influences consequence classification of the dam and consequent design requirements.
The work involves running hydraulic model tests, with the possibility of combining this with numerical analysis.
The project aims at answering questions relating to the importance of the dam toe and the downstream rip-rap protection in overtopping situation, as well as for safe passage of through-flow. Furthermore, it aims at providing information on the breaching mechanism of embankment dam types built according to Norwegian design and construction practice. The research should provide information of value for the development of optimum design and construction of the dam toe and abutments of earth-rockfill dams with placed riprap stones on the downstream slope. Furthermore, information on breaching mechanism may influence dam design, consequence classification as well as be of value in emergency planning.