MECHANICS OF BEACH DEFORMATION DUE TO BREAKING WAVES

1.破碎波特性实验：采用0.019 ~ 0.048的四种深水波陡进行实验。在坡度为1/15的情况下，测量了破碎波的波形和破碎点附近的速度。研究结果如下：（1）阐明了本研究所研制的热膜流速仪校准装置的可行性。(2)通过对破碎点附近雷诺应力随时间变化的测量，发现了与破碎波引起的湍流的产生和发展有关的喷射或扫掠现象。(3)在深水波陡较大的情况下，通过研究脉动湍流速度分量的变化，表明湍流传播到破碎点的离岸区域。2.二维海滩剖面变形：在与深水波相同的条件下，进行了海滩剖面变形的实验。结果表明：（1）二维海滩剖面在宏观上可用正交多项式表示。(2)阐明了近海输沙率是用正交多项式计算的。除海滩剖面的随机变化外，宏观上与前人的研究结果基本一致。

1. Experiments on characteristics of breaking waves: Experiments were carried out by using four kinds of deep-water wave steepness, that is the values of 0.019 to 0.048. The wave profiles of the breaking waves and the velocities near breaking points were measured on the slope of 1/15. A summary of the results is as follows:(1) It was clarified that a new instrument of calibration for hot-film velocity meter, which was developed in this study, is available to calibrate easily. (2) The phenomena of ejection or sweep which are related to the generation and development of turbulence due to breaking waves were found by the time variation of Reynolds stresses measured near the breaking point. (3) In the case of large values of deep-water wave steepness, it is shown that the turbulence is propagated to the offshore region of breaking point by investigating the variation of the fluctuating turbulent velocity components.2.Deformation of two-dimensional beach profiles: Experiments on beach profile deformation were conducted by the same condition with that of dreaking waves. The results obtained are summarized as follows:(1) Two-dimensional beach profiles may be expressed in terms of the orthogonal polynomial macroscopically. (2) It is clarified that on-offshore sediment transport rate is calculated by applying the orthogonal polynomial. The results agree with those of previous studies macroscopically, except the randam variation of beach profiles.