INVESTIGATIONS ON HYDRAILIC FORCES DUE TO CURRENT INCLUDING CORAL PIECES ACCOMPANIED BY BREAKDER AT REEF FRONT AND WAVE DAMPING EFFECT OF SEA BEDWITH GROUP OF CORAL BLOCKS

研究采用现场观测、模型试验和理论分析相结合的方法。本次调查的主要结果可概括如下：(1)在台风条件下对礁岸进行观测后发现，波高随从礁前破碎点向岸边移动呈指数递减，与作者提出的公式计算结果吻合较好，公式中系数的取值是相对深度与入射波高的函数。(2)从实验上阐明了破碎波在礁锋产生激流的力学过程，并根据溢流型和俯冲型破碎波的方式将流分为两种类型。阐明了珊瑚块体海床的减浪效应不仅取决于通常的海床摩擦效应，而且还取决于珊瑚块体的形状阻力效应，即每个块体后面的尾迹。通过与现场观测结果的对比，验证了实验结果的正确性。

The investigation carried out through field observations, model experiments and theoretical analysis. Main results of this investigation can be summerised as follws ;(1) It is clarified after fied observations on reef coasts under typhoon conditions that the wave heights reduce exponencially with traveling from the breaking point in front of reef to seashores, and shown good agreement with caluculated result by the formula suggested by the authors, where with the value of oefficients of the formula decided as function of relative depth to incident wave heights in the sea coast.(2) The mechanical process of breaking waves result in violent current at the reef front have been clarified experimentally, and the currents are categorised in two types according to the patern of wave breaking of spilling or plunging breaker.(3) Experimentallly, it has been clarified that wave damping effects of the sea bed with coral blocks depend on not only usual frictional effect of the sea bed, but also the effects of form resistance of coral blocks due to wakes that occure behind each block. The experimental results were verified by comparison with the fields observations.