석션파일 케이슨 방파제의 거동에 대한 현장 계측

Abstract

The location of new ports in Korea has changed to the site with severe or extreme environmental conditions including deep water, high waves, very soft grounds. Therefore, the demand for the development of new type breakwater, which is applicable to the soft ground and deep water depth with high efficiency and low economic costs, is gradually increased. The gravity type concrete caisson breakwater using suction piles as substructures has been introduced in this study. It utilizes a gravity-type concrete caisson superstructure on top of the suction piles that act as the sub-surface foundation for the caissons. Suction piles do not require the excavation of soft seafloor soils, but penetrate into the soft seafloor soil to depths where sufficient soil-bearing capacity is expected. The new breakwater system (the length of 50m) with suction pile was designed and successfully constructed as part of experimental project between 2004 and 2007, at the location where northern breakwater of Ulsan new port were scheduled to be constructed. Eight suction piles with diameter of 11m and three caissons were installed. The monitoring systems were also attached to the structure in order to measure and analyze the behaviors of the breakwater and suction piles. Using various measuring sensors and the data loggers powered by solar system, the static data such as relative displacement and inclination angle of the caissons, pore pressure and effective stress of the suction pile etc. have been monitored in every 2 seconds, the dynamic data such as wave force and wave height have continuously been measured. Besides, the scouring depths around the suction piles have also been observed. The measured results revealed that during about 13 months there is no significant movement of the breakwater against the maximum significant wave height of 4 m, which is the maximum value in front of the breakwater, thereafter, the performance of the new breakwater system was verified within tested wave conditi