复合坡度珊瑚礁地形上波浪破碎的试验研究

Experimental study of waves breaking over coral reef topography of a composite slope

通过波浪水槽试验,研究了珊瑚礁地形上规则波的破碎特征,包括破碎类型、破碎波高、破碎位置以及破碎带宽度。试验在带礁缘的复合坡度断面下进行,测试了两种水位下系列波高和波周期相组合的工况。试验研究了波浪破碎类型的区分标准,评估了已有四类破碎指标在复合坡度珊瑚礁地形上的适用性,并给出了描述破碎位置和破碎带宽度的经验公式。结果表明:礁边水深深水波高比可较好地区分波浪的破碎类型;四类破碎指标关系式中以破碎波高深水波高比之于深水波陡的相关性为最优;深水波高和礁边水深是影响破碎位置和破碎带宽度的主要因素,随着深水波高礁边水深比的增大,量纲一破碎位置(破碎点与礁边的距离和礁边处浅水波长的比值)逐渐减小,量纲一破碎带宽度(破碎带宽度和礁边浅水波长的比值)逐渐增大。

A series of wave-flume tests were performed to study the characteristics of regular waves breaking on coral reefs,including the breaker type,breaker height,breaker position and surf-zone width.The tests were performed on the composite slope section of a reef rim at the specified conditions combined with serial wave heights and wave periods for two water levels.The test studied the criteria for differentiating the breaker types,assessed the applicability of the four breaker indexes on coral reefs with a composite slope,and provided an experience formula describing the breaker position and surf-zone width.Thus the following conclusions were drawn：the breaker types could be differentiated by the ratio of reef-edge water depth to the deep-water wave height;in the relational expressions of four breaker indexes,the correlation between the ratio of breaker height to deep-water wave height and the deep-water wave steepness was the best;the deep-water wave height and reef-edge water depth had great influence on breaker position and surf-zone width;with the increase in the ratio of deep-water wave height to reef-edge water depth,the dimensionless breaker position（the ratio of distance between the breaker point and the reef edge to the reef-edge shallow-water wave length） decreased and the dimensionless surf-zone width（the ratio of surf-zone width to reef-edge shallow-water wave length） increased.