CHARACTERISTICS OF RESPONSE OF FLAP GATE TYPE SEAWALL TO WAVES

Abstract

 A flap-gate type seawall, which usually lies down on ground, rises up automatically by buoyancy during inundation by tsunamis or storm surges, and then it forms a continuous seawall. This facility has counterweights, which assists a gate in rising and falling, on both sides of the gate. These counterweights increase tracking of the gate according to change in water levels. In this study, responses to waves were compared through a hydraulic experiment with both a model equipped with a counterweight (hereafter weight-type) and a model having enough buoyancy to float without additional assists (hereafter simple type). Wave pressures acting on each gate were also evaluated. Initial water levels, wave heights and wave periods of regular waves were adopted as parameters. As a result of the experiments, the weight-type was equipped with the counterweight with restoring force more than a certain level regardless of the water levels compared to the simple type, so the response amplitude and the wave pressures acting on the gate were stable.