Overtopping dike-breach: effect of grain size distribution

ABSTRACT

A series of plane dike overtopping laboratory tests is reported, in which the effect of sediment mixture on the breach process is investigated. Three different sediment mixtures were tested, in addition to the reference dike consisting of uniform non-cohesive sediment. No sealing elements or surface protection were applied. The adopted constant reservoir inflow led to a falling reservoir scenario. The experiments demonstrate that the grain size distribution has a small effect on the overall breach process within the given test range, as the hydraulic conditions during the dike breach are much above the sediment entrainment condition. No increased erosion resistance was observed for the sediment mixtures. Therefore, the mean sediment diameter adequately describes the non-cohesive material characteristics and general dike-breach features in laboratory scale can be investigated using uniform material. This finding is significant both for laboratory experimentation and for prototype dike construction.

Keywords:

• Dike breach
• flood embankment
• hydraulic modelling
• laboratory tests
• overtopping erosion

Acknowledgements

The authors thank Elias Winz for his laboratory assistance.