Probing into the effect of water depth on stability number of the rubble mound breakwater

Predicting the stability of armor blocks of breakwaters and revetments is a very important issue in coastal and ocean engineering. The stability number deepens on the sea state and structural parameters. One of the most important parameters which can affect the stability of the rubble mound breakwater is water depth. On the other hand, selection of an appropriate wave height parameter is very vital in predicting the stability number. Recently, H50, the average of 50 highest waves that reach the breakwater in its useful life, has been used to predict the stability of the armor layer. In this paper, water depth parameter is used in wave length and surf similarity parameter in breakwater’s toe, is applied. A new formula is also developed based on H50 and surf similarity parameter in breakwater’s toe. Two experimental data sets of irregular waves are used to develop the new formula using the model tree. Results lead to the proposal of a single formula that includes tow formula. This implies that the stability number is independent of wave breaking type. Moreover, the proposed formula is found to produce more acceptable results than available empirical formulas for predicting the stability number.