Performance evaluation of open-cell caisson breakwater system using finite element method
Recently, coastal city and facilities had many damages by abnormally high waves with climate change. Especially, breakwater systems based on a caisson-type harm damages in Korea because they are located in the outside port. In order to reduce theses damages, new type breakwater systems using interlocking caisson are researched. Generally, caissons of breakwater system were constructed on crushed rock mound. They had a little space of 10–20 cm between each caisson. In this reason, they resist separately under external environmental ocean condition. A resistance mechanism of this method is friction force between caisson and crushed rock. Majority of failure is sliding failure, when it is exposed to more than design load. On the contrary, new type breakwater system as interlocking caissons resists effectively against abnormal wave because they are connected by specific joint method between each caisson. In this study, based on an open-cell caisson which is one of the interlocking concepts, we evaluated the performance of dynamic behavior for breakwater system using finite element analysis such as distribution subgrade reaction force, structural behavior of global system etc. According to analysis result, the open-cell caisson has good performance compare with general caisson type.
Wave Impacts on Caisson Breakwaters Situated in Multidirectionally Breaking Seas
The paper concerns horizontal wave forces on caisson breakwaters in multidirectional breaking seas. It is based on model tests performed in a 3D wave tank at Hydraulics and Coastal Engineering Laboratory, Aalborg University. The measured horizontal wave forces are compared to the Goda force. Good agreement with the Goda formula is found for waves not breaking directly on the structure, while increasing degree of breaking on the structure results in forces of up to 50 % higher than the Goda force. Furthermore, the reduction of the horizontal wave force on long structures due to the non full correlation of the wave pressure along the structure is investigated. A formula for the force reduction factor based on cross correlation coefficients is given as a function of the mean wave direction and the wave spreading.
EFFECTS OF SHORT-CRESTEDNESS ON WAVE LOADS ON LONG STRUCTURES
The effects are considered of short-crestedness of incident waves on the load which these exert on a long structure. The result is expressed as a frequency-dependent, directionally-averaged spectral multiplication factor for the load relative to the case of normally incident, long-crested waves. This is evaluated numerically for a cos2 θ-type directional incident spectrum, and various relative structure lengths. Calculated crest elevations, averaged over different lengths, agree well with the empirical ones, for ocean-wave data as well as for laboratory wind-wave data.