Calibration of Load and Resistance Factors for Breakwater Foundation Design. Application on Different Types of Superstructures

Load and resistance factor design is an efficient design approach that provides a system of consistent design solutions. This study aims to determine the load and resistance factors needed for the design of breakwater foundations within a probabilistic framework. In the study, four typical types of Korean breakwaters, namely, rubble mound breakwaters, vertical composite caisson breakwaters, perforated caisson breakwaters, and horizontal composite breakwaters, are investigated. The bearing capacity of breakwater foundations under wave loading conditions is thoroughly examined. Two levels of the target reliability index (RI) of 2.5 and 3.0 are selected to implement the load and resistance factors calibration using Monte Carlo simulations with 100,000 cycles. The normalized resistance factors are found to be lower for the higher target RI as expected. Their ranges are from 0.668 to 0.687 for the target RI of 2.5 and from 0.576 to 0.634 for the target RI of 3.0.

Influence of the Perforated Rate on the Wave Attenuation Performance of Perforated Caisson Set on a Rubble Bed

A Jarlan-type perforated caisson (JTPC) was an important form of structure in offshore and coastal engineering and its wave attenuation performance was greatly affected by μ (the perforated rate). In the present research, a numerical model based on VARANS equations was tested by comparing the simulation results with physical experiments and then adopted to study the effect of a larger range of μ on wave attenuation performance which included both the horizontal wave forces and the reflection coefficients. Conclusions were drawn that the total horizontal wave force and the reflection coefficient both tended to decrease and then increase with increasing μ; when the reflection coefficient reached its minimum value as about μ=0.2, the wave force at the seaward side of the perforated front wall tended to be equal to that at the solid rear wall; the total horizontal wave force reached its minimum value as about μ=0.3.

Numerical investigation into effect of the rubble mound inside perforated caisson breakwaters under random sea states

The paper reports a numerical investigation into the effect of rubble mounds inside perforated caisson breakwaters (PCBs), in which a line-shaped mass source wavemaker is proposed for generating random waves. A series of experiments are employed to validate the numerical model, and good agreements are observed in the comparison of the experimental and numerical results. With the use of the validated numerical model, the numerical investigation is performed, in which the attention is mainly paid to two parameters: the slope angle and porosity of the inner rubble mound. The result shows that, as the slope angle of the inner rubble mound increases, the reflection coefficient is observed to decrease first and then increase, and compared to the experiment, both the positive and negative hydrodynamic pressure acting on the solid rear wall of PCBs is weakened. On the other hand, although a larger inner rubble mound porosity is beneficial to diminish the reflection coefficient, the reduction is not obvious especially when the front wall porosity is small. Furthermore, as the increase of front wall porosity and relative wave absorption chamber length (the ratio of wave absorption chamber length to significant wavelength), the effect of the slope angle and porosity of the inner rubble mound becomes more significant because more waves could enter the wave absorption chamber. The relative wave absorption chamber length considered in the present study ranges from 0.06 to 0.21, and the recommended slope angle is approximately 45 degrees.

Influence of Wave-Absorbing Chamber Width on the Wave Attenuation Performance of Perforated Caisson Sitting on Rubble-Mound Foundation

A Jarlan-type perforated caisson consisted of a perforated front wall, a solid rear wall, and a wave-absorbing chamber between them. The wave-absorbing chamber was the main feature of the perforated caisson, and its width had a great effect on wave attenuation performance. In this study, a larger range of the wave-absorbing chamber width was observed in model experiments to investigate the effect on wave attenuation performance including the reflection coefficients and the horizontal wave forces of a perforated caisson sitting on a rubble-mound foundation. A resistance-type porosity numerical model based on the volume-averaged Reynolds-averaged Navier–Stokes (VARANS) equations was validated by comparing the present results with those of previously reported and present experiments. The validated numerical model was then used for extended research. It was found that the reflection coefficients, the total horizontal wave force, and its components all tended to oscillate in a decrease ⟶ increase ⟶ decrease manner with increasing the wave-absorbing chamber width. The reflection coefficients and wave forces acting on both sides of the perforated front wall were found to be synchronized regardless of perforation ratio or the rubble-mound foundation height.