Practical methods of estimating tilting failure of caisson breakwaters using a Monte-Carlo simulation

The authors propose a new method to estimate the tilting failure of caisson breakwaters, using a Monte-Carlo simulation that can quantitatively and stochastically estimate failure probability. An index, referred to as "Expected Frequency Exceeding of a Critical Load (EFEC)" that expresses the potential tilting failure probability of caisson breakwaters is proposed and adopted in this model. Application of the model to 40 breakwaters in Japan reveals that the threshold value of EFEC that specifies whether a caisson breakwater is safe or unsafe could lie in the range from 0.02 to 0.04. The authors also found that unstable caisson geometry, showing a large value in the aspect ratio of the caisson, can provide additional indication of when tilting failure is likely to occur. It is expected that the present method can provide a practical way for engineers to judge the possibility of tilting failure in caisson breakwaters.