对称波形底箱型水面防波堤性能试验研究

Experimental study on the performance of a box-type free-surface breakwater with symmetrical wavy bottom

为了提高箱型水面防波堤的消波性能,将箱型水面防波堤的主体底部外形进行了改造,即将主体底部由平底改造为对称波形底,提出了一种对称波形底水面防波堤。对平底和对称波形底箱型防波堤分别进行了物理模型试验研究。试验时,将平底和对称波形底的方箱型消波主体通过支架固定在小型波浪水槽中,保持水槽水深不变,改变箱体吃水、波陡、波长,进行了系列试验。给出两种模型的透射系数、反射系数和能量损耗系数随相对宽度BL的变化规律。通过比较发现:对称波形底的消波性能比平底的优良,增加的消波效果高达60%左右;两种模型的反射系数相差无几,说明改变箱型底部结构对于防波堤反射性能的影响不大;对称波形底对于波能的损耗作用要强于平底。

In order to improve the wave attenuation performance of a box-type free-surface breakwater,the bottom contour of the box is transformed from flat to symmetrical wavy by modifying the bottom contour of the box,so a kind of symmetrical wavy-bottom free-surface breakwater is proposed.The physical model tests are carried out for flat-bottom and symmetrical wavy-bottom respectively. During the tests procedures, the main bodies of the two breakwater models are fixed in the small wavemaker flume through the brackets,and the flume water depth are kept unchanged.A series of experiments are carried out through changing the box immersion depth,the wave steepness and the wavelength.The variation of transmission coefficient,reflection coefficient and energy dissipation coefficient with relative width BL is given.By the performance comparison,it is found that the wave attenuation performance of symmetrical wavy bottom is better than that of flat bottom,and the increased quantity of wave attenuation effect is up to 60%;the reflection coefficients of the two models are almost the same, which indicates that changing bottom contour of the box has little effect on the reflection performance of the breakwater;the symmetrical wavy bottom dissipates more wave energy than the flat bottom.