펜타포드와 Y블록의 안정성실험 및 소파성능 평가

Abstract

Pentapod and Y-block which are new shapes of armouring block for the breakwater protection are developed in this study. The two blocks have remarkable feature in interlocking structure. Hydraulic wave test and numerical simulation using the block models were experimented to evaluate the interlocking stability and to determine the design parameters. Thousands of concrete block models were piled up one by one neatly in a two dimensional wave channel at 1:1.5 slope. Every 200g blocks was stable in the condition of 0.99 to 1.98 second of wave period and 4 to 14cm of wave height. This is because the interlocking feature of the blocks increases the resistance against the wave. Based on similarity laws, these are 25ton blocks which are installed in 18m depth of sea and faced on 7 to 14 seconds of wave period with 2 to 7m of wave height. Reflection rate of the Y-block was ranged 0.513 to 0.853 at the above wave period and wave height condition. Reflection rate of Pentapod block was similar to that of Y-block. Reflection rate of the two shapes of block calculated from numerical simulation were similar to the measured rate for the above wave period and wave height. Numerical experiment can simulate overtopping height at a various wave condition. Results showed that overtopping height was directly proportional to the wave height and wave period. Among the 4 to 14cm wave height and 0.99 to 1.98 second of wave period conditions, the highest overtopping was observed as high as 0.2223 at the condition of 1.98 second of wave period and 14cm of wave height which is the highest condition in this experiments. This means overtopping height is 1.6 times higher than wave height. Hydraulic channel tests using model blocks and numerical experiments using CADMAS-SURF showed that design parameters of reflection rate and overtopping characteristics of the two shapes of block were similar to popular tetrapod.