A Fundamental Study on Breaking Limit and Breaking Process of Multidirectional Random Wave.

水下防波堤在多向随机波场中的破断极限和破断过程主要是通过室内实验进行研究的。取得的研究成果如下：(1)为测量多向随机波的分断极限，在国际上首次研制了由12个电容式传感元件组成的分断波计。破波计已被证明是测量破波起始和破波的有力工具。(2)相对破碎波高H_b/R （H_b；破碎波高，R；树冠淹没深度）随着扩展参数的增大，总体上减小，S_<max>。(3)临界波陡H_b/L_*（深水波长）表示为：H_b/L_* = O.lO7tanh (K_*R)，其中K_*为深水波数。(4)随着扩散参数S_<max>的增大，相对破碎波高H_6/R的散射增大。(5)由于波浪的衍射和反射作用，淹没式防波堤侧端处的破浪高度一般大于防波堤中部。

Breaking limit and breaking process due to the submerged breakwater, in the multidirectional random wave field, have been investigated mainly from laboratory experiments. The research results achieved are listed as follows :(1) The breaking wave gage with 12 electrical capacitance-type sensing elements has been newly developed, for the first time in the world, in order to measure the breaking limit of multidirectional random wave. The breaking wave gage has been shown to be very powerful to measure the breaking inception and breaking wave.(2) The relative breaking wave height, H_b/R (H_b ; breaking wave height, R ; submerged depth of crown) becomes smaller, in general, with increasing of the spreading parameter, S_<max>.(3) The critical wave steepness, H_b/L_* (L_* ; wavelength in deepwater) is formulated as,H_b/L_* = O.lO7tanh (K_*R)Here, k_* is the wave number in deepwater.(4) The scattering of the relative breaking wave height, H_6/R becomes larger, as the spreading parameter S_<max> increases.(5) The breaking wave height at the side-ends of the submerged breakwater becomes, in general, larger than that on the central part of the breakwater, due to wave diffraction and reflection.