Simultaneous measurement of wave forces and pressures on a double-chamber perforated caisson

Abstract

Accurate measurement of wave forces and pressures on coastal and offshore structures is extremely important for the evaluation of the structure stability against wave loading. This study introduced a hybrid measurement technique of using S-beam load cells and disc-type pressure transducers simultaneously. A novel instrumentation of tiny load cells together with pressure transducers were developed to measure the wave loading on a double-chamber perforated caisson. After carrying out experiments with great care, a detailed comparison is given between the directly measured forces and those estimated from the integration of the pressure records. Excellent agreement was observed between the wave forces that were obtained by the two methods, showing the index of agreement of 0.96 on average. Although this technique is very simple to apply, it has an advantage of measuring the wave force acting on the entire structure, while obtaining the forces and pressures on the individual components of the structure at the same time. Hence, this method can provide crucial information required for the design of coastal and marine structures having many elements, such as coastal bridges, refuge buildings against tsunamis, offshore platforms, as well as perforated caissons.

Evaluation of the Hydraulic Performance of a Rear-Parapet Vertical Breakwater under Regular Waves through Hydraulic Experiments

“…In these cases, the bearing pressures for the parapet located at the center and on the harborside are reduced by approximately 7.5% and 47.6%, respectively, compared with that for the parapet located on the seaside. Considering a scale of 1/40, the bearing pressures for the parapet located on the harborside (Model 3) are 301.84, 289.95, and 273.86 kN/m 2 , which are lower than the allowable bearing pressure of 600 kN/m 2 [34]. Thus, the width of the caisson, which was set to 20 m (50 cm for the model scale), can be reduced in the test conditions of this study, and the rear-parapet vertical breakwater is more stable than the other parapet breakwaters in terms of stability against the bearing pressure.…”

“…When the parapet is moved from the seaside to the harborside, a phase difference is induced as the water particle reflected from the parapet placed on the seaside in the same phase moves to the upper part of the caisson and is reflected from the parapet placed on the harborside or at the center. In this process, as shown in Figure 4, energy dissipation occurs because of turbulence, such as in the case of a perforated caisson with a wave chamber and perforated wall [33,34]. A significant portion of the wave energy is also dissipated by wave breaking, splashing, and water falling with air bubbles.…”

Experimental Investigation of Horizontal Wave Pressure on the Caisson Protected by Armor Blocks on the Rubble-Mounted Core

“…Caisson models made of acrylic plates were placed on the 10 cm high rubble mound that was located at a distance of 28 m from the wave paddle. Following the measurement techniques used in the previous studies [6,14], horizontal wave loading was measured by using miniscule disk-type pressure transducers. As shown in Figure 6, the pressure transducers were embedded into the center of each plate to measure the horizontal wave pressure.…”

Change of Horizontal Wave Pressures on a Caisson Depending on the Crest Level of Armor Layers on the Rubble Mounted Core

“…Figure 2 shows diagrams of the model of 0.6 m high. Wave pressures were measured by miniscule disk-type pressure transducers with a diameter of 10 mm, which has been used in Oh and Ji (2019). The front face of the model consists of multiple acrylic plates.…”