Numerical Evaluation of Stability Methods for Rubble Mound Breakwater Toes

Since 1977 dedicated studies are made to the stability of rubble mound break-water toes under wave attack. A large number of stability methods is available, but prediction accuracy is low and validity ranges are too small for use in prac-tice. In this research the decoupled model approach is used to evaluate predic-tion capacity of existing toe stability methods. The approach uses numerical model IH-2VOF for a prediction of stability. Review of the model showed that it is highly sensitive to stone properties and that turbulence was not modelled. Un-der the assumption that the latter is not of major importance, calibration of mo-tion formulae against physical measurements and evaluation of the stability methods was performed. The decoupled model approach appeared to give good stability predictions. Validity limits of the stability methods seemed to be too strict. A ranking of stability methods was made. Future validation should con-firm the results before incorporation in design manuals.