Narrow Results

Near-bed structures are studied in this paper, in particular submerged rubble mound structures with a relatively low crest such that wave breaking does not have a significant influence. Physical model tests have been performed to study the stability of near-bed structures under wave loading, with or without a current. Based on the new data and an analysis of existing data, several methods to predict the stability of near-bed structures have been analysed. One of these methods was found to be the most appropriate. This method was calibrated to relate the erosion of near-bed structures to a mobility parameter. It was found that for low-to-moderate currents in combination with waves, the waves dominate the stability of the rock material; the stability of the near-bed structures can be predicted without taking the influence of the (following) current into account. The obtained prediction method is simple and accounts for the effects of wave height, wave period, number of waves, stone diameter, rock density and crest elevation. More detailed information can be found in Van Gent and Wallast (2001).