AN EXPANSION OF THE RELIABILITY DESIGN METHOD FOR CAISSON-TYPE BREAKWATERS TOWARDS DEEP WATER USING THE FOURTH ORDER APPROXIMATION OF STANDING WAVES

摘要

The main purpose of this research is to introduce the perspective of standing waves to the conventional reliability design method for breakwaters. For this purpose, the fourth approximation to the pressure of standing waves derived by Goda et al. (1966) is employed to assess wave pressures due to standing waves. Using this approximation for the deformation-based reliability design method regarding caisson-type breakwaters, sliding distances caused by standing waves in severe storm surges can be evaluated properly without any fictitious modeling for the time history of the wave pressure. The results obtained by Monte Carlo simulations show that the risk of sliding due to standing waves will rapidly increase as the water depth increases. A case study for a caisson at a depth of 20m shows that the expected sliding distance is 1.3m, 71% of which is caused by standing waves. The importance of considering the effect of standing waves should be recognized when breakwaters are to be built in deeper water using the reliability design method.