Overtopping and breaching of rockfill dams with and without a central core

Abstract

Embankment dams are vulnerable to excessive through flow and overtopping due to erodible and pervious nature of materials used such as rockfill and earthfill. Majority of dams in the world are embankment type which pose serious risks and possible hazards in the downstream areas in case of failure. The seriousness of this topic has created a huge demand for dam safety and regulation. It is therefore very important to have a reliable consequence classification of dam. Implementation of the regulations and the proper design requirements demand full knowledge and understanding of dam behaviour during failure and in extreme load situation. So this study has become a step forward in the direction of defining and evaluating breach process and parameters. Eight different physical models are presented here which include dams with central core and without core. All of these are rockfill dams and subjected to excess through flow and overtopping, and the results are observed for both the types. It was noted that dams without central core see excess throughflow while dams with core failed mostly with overtopping. Unlike dams with additional protection layers, there is no sudden breakout and collapse giving huge downstream flood. However the peak discharge associated with the dam breaching is significant and should be addressed in the floodzone mapping. Some already existed parametric models are also employed to compare results with the physical modelling. Softwares like SFM (Agisoft), GIS, R programming script help to handle big data files and extract quality result from the analysis.