Reshaping Breakwaters: on the stability of roundheads and trunk erosion in oblique waves

The paper deals with the 3-dimensional stability of the type of rubble mound breakwaters where reshaping of the mound due to wave action is foreseen in the design. Such breakwaters are commonly named sacrificial types and berm types. The latter is due to the relatively large volume of armoure stones placed in a seaward berm. However, as also conventional armoured breakwaters sometimes do contain a berm it is assumed that a better and more ambiguous designation would be "reshaping" rubble mound breakwaters.

The stability of a reshaping type breakwater was tested in a 3-dimensional model at The Hydraulics Laboratory, Department of Civil Engineering, University of Aalborg. The object was to study the stability/erosion of the breakwater head and the trunk, the latter exposed to both head-on and oblique irregular waves. To avoid too many parameters a simple breakwater geometry and only one class of stones were used.