A Comparative Study on Van der Meer (1988) and Van Gent et al. (2004) Stability Formulae

For the stability of rubble mound coastal defense structures, Hudson (1959) developed a formula based on model tests with regular waves. Later, a formula by Van der Meer (1988) is given for relatively deep water conditions at the toe of the structure with an application to moderate shallow water based on model tests with irregular waves. Van Gent et al. (2004) proposed a modified formula to extend applicability of the Van der Meer (1988) formula to shallower water. In the literature, design constraints concerning the application of Van der Meer (1988) and Van Gent et al. (2004) stability equations are given. Using these design constraints, a comparative study on the stability of rock slopes under the same design conditions is carried out. The results are presented as graphs of depth at the toe of the structure over significant wave height at the toe of the structure (h/Hs/Dtoe/N) versus armour stone diameter (D/Dn50/N) and relative difference in armour stone diameter. The discrepancies observed in the results in the application of stability formulas under the same design conditions are discussed.