RESEARCH ON THE SAFETY EVALUATION AND RELIABILITY DESIGN AGAINST WAVE ACTION FOR ARMOR BLOCK BREAK WATER

本研究旨在通过室内试验研究碎石(块)防波堤可靠性分析的可能性。防波堤模型放置在1/30的底部坡度上。其前后坡度均为4/3。模型由平均24.5克的碎石组成。试验中采用T=1.0s和1.4s(波周期)，H=5-20 cm(波高)的周期波，测量了防波堤在波浪作用下的表面轮廓变化。这些变化是用放置在波浪水箱一侧的摄像机记录的。利用计算机的叠加功能对记录进行分析。在波浪作用的乞求过程中，剖面变化非常迅速。然而，当轮廓达到“稳定的S型轮廓”时，它逐渐减小，并最终停止。剖面的变化形式为：S=c_0，c_1EXP(-c_2n)，其中c_0，c_1，c_2为常数，n为波数。在本研究中，还模拟了轮廓的形状。在相同的波高和周期下，通过反复试验，得到了给定波高和周期条件下以n表示的期望坡度分布。将期望波浪剖面与瑞利波高分布联系起来，以n为单位计算了期望剖面的变化。根据本研究的结果，在块体防波堤稳定性的模型研究中，表明了进行3级防波堤可靠性分析的可能性。

This study aims at studying the possibility of reliability analysis for a rubble (block) break water through laboratory experiments. The break water model is placed on a bottom slope of 1/30. Its fore- and back surface slopes are both 4/3. The model is composed of crashed stones with 24.5g (average). Periodic waves with T=1.0s and 1.4s (wave period), and H=5-20cm (wave height) are used in the experiments to measure the surface profile changes of the breakwater against wave actions. The changes are recorded with the video camera placed side of the wave tank. The records are analyzed using the super-impose function of a computer. The profile change is very quick in the beggining of the wave actions. However, it reduces gradually and stops finally when the profile reaches to the "stable S-shape profile". The profile changes are formulated in the form of S=c_0+c_1EXP (-c_2n), where c_0, c_1, c_2 are constants and n is the number of waves acted. The shape of profile are also modeled in this study. Expected slope profiles for given conditions of wave height and period in terms of n are obtained through repeated experiments with the same wave height and period. Connecting the expected wave profiles with the Rayleigh wave height distribution, the expected profile changes are calculated in terms of n. From results of this study a possibility of the reliability analysis of the level 3 is shown in a model study of a stability of block break water.