| dc.description.abstract | Embankment dams, particularly rockfill embankment dams are subjected to destructive breakout floods as a result of overtopping due to their pervious and erodible characteristics. Ripraps are a sort out solution to overcome this problem. Norway in particular specializes in implementing placed riprap on the upstream and downstream slope and at the crest. Models are required to evaluate the breach development in order to determine the consequences of a dam breach. Even though many parametric models exist, there is a lot of uncertainty with regards to aspects such as varying material properties, and also the effects of erosion protection. Thus, it is of interest to examine the breach mechanism of rockfill dams with erosion protection on downstream slope in order to establish a more reliable and well-founded consequence classification as well as downstream flood inundation areas in case of breaching. In this study 1:10 physical scale models were constructed and subjected to overtopping flow to examine the breach mechanism and failure discharge. The investigation consisted of six model tests which included three dams with just well graded rockfill material while the other three included a supplementary filter and riprap layer. The study did reveal that the structural stability of the dam considerably increases with the additional protection. However, when the dams with protection do fail as a result of the riprap sliding the resulting failure discharge is much greater. For an optimized design the costs will have to be balanced with the desired structural stability. Nonetheless, this study is a step forward in defining breach parameters for a conventional Norwegian rockfill dam. | |