双层水平板防波堤水动力特性研究

发布时间：2018-01-13 08:07

本文关键词：双层水平板防波堤水动力特性研究　出处：《大连理工大学》2014年博士论文　论文类型：学位论文

【摘要】：双层水平板防波堤是一种新型的环保型防波堤结构,与传统防波堤相比有很多优点：(1)允许水体在防波堤内外自由交换,不破坏海洋环境；(2)结构简单,便于施工；(3)造价随水深的变化不敏感。该结构实用化的主要障碍在于缺乏消浪效果定量化评价方法及实用化荷载计算方法,因此开展双层水平板防波堤水动力特性的研究对于该结构推广应用具有现实意义。本文采用物理模型试验和数值模拟计算相结合的方法,对双层水平板防波堤的消浪效果和水动力特性进行了研究,对消浪机理进行了探讨,得到以下主要研究成果： (1)关于透射系数和波浪总力的计算方法综合考虑了相对板宽B/L、相对波高H/D、波陡H/L、相对板间距S/D和相对潜深d/D五个影响因素,用最小二乘法拟合给出了透射系数和竖向波浪总力的计算公式。 (2)关于双层水平板防波堤周围的流场结构和消浪机理双层水平板改变了波浪水质点运动形态。双层水平板防波堤周围的流场结构具体表现为：潜式堤双层板之间的流场呈水平往复流动状态,潜式堤和出水堤的下层板到水底之间的流动也接近水平往复流。潜式堤的上层板上表面到自由水面、出水堤的下层板上表面到自由水面之间存在涡动。最大涡强随波浪传播而移动。涡强度的时空变化及脱落的周期性与入射波浪周期一致,上述流场变化决定了水平板上压力的变化。双层水平板对堤前流场的影响范围不超过1倍板宽,对堤后流场的影响范围较大。不同位置分层剖面的波能流沿水平板有均匀差异。波能流在潜式堤的双层板之间以及在潜式堤和出水堤的下层板下方可以发生逆向传递。涡动能量损耗及双层板所在水域波能流的逆向传递是双层板防波堤消浪的主要机理。 (3)关于双层水平板的消浪性能波浪与双层水平板防波堤作用后,双层水平板起到了消波(反射和损耗部分波浪能量)和改变波频的双重作用。潜式堤和出水堤堤后的波面含有2阶及以上谐波成分,特别是当相对板宽小于0.5时,高阶谐波成分占有能量比例较大,一定条件下可达到1阶谐波占有能量比例相当的程度。因此采用谐波能量叠加法定义的透射系数(式2.5)更具合理性。透射系数受诸多参数的耦合影响,并非双层水平板越宽,对单色波浪的消浪效果越好,在0.29～0.72倍相对板宽范围内,透射系数随相对板宽的变化呈波动型式；在相对潜深d/D=-0.25～+0.17试验范围内,相对潜深对透射系数的影响并不十分显著。 (4)关于波压力及其分布潜式堤和出水堤的波压力以1阶频率为主,2阶、3阶频率较小,其它高阶频率可以忽略不计。双层水平板不同受力位置波动压力有较大差别,出水堤上层板露出水面时,上表面波压力很小,下表面前、后端易出现冲击压力；出水堤下层板淹没时,呈现出与潜式堤大体相同的时域特征。但潜式堤淹没较深时,下层板尾端易出现高频波动压力。对波压力包络分布而言,相对潜深d/D、相对板宽B/L和相对波高H/D均对波压力包络分布有影响,但是相对潜深d/D对上层板的上、下表面的波压力包络分布影响较大,即潜式堤的上层板上表面受到较大的波压力,而出水堤受到的波压力较小；出水堤的上层板下表面受到较大的冲击波压力,潜式堤的上层板下表面则未出现冲击特性。
[Abstract]:Double horizontal plate breakwater is a new type of environmental protection type breakwater structure has many advantages compared with the traditional breakwater: (1) to allow the free exchange of water in the breakwater inside and outside, without damage to the marine environment; (2) has the advantages of simple structure, convenient construction; (3) the cost with the water depth is not sensitive to the variations of major obstacles to the practical structure. The calculation method of wave dissipation effect is the lack of quantitative evaluation methods and practical load, so the study on the dynamic characteristics of double horizontal plate breakwater has practical significance for the promotion and application of the structure.
Based on the combination of physical model test and numerical simulation, the wave dissipation effect and hydrodynamic characteristics of a double-layer horizontal breakwater are studied. The mechanism of wave dissipation is discussed, and the following research results are obtained.
(1) the calculation method of the transmission coefficient and the total wave force
Considering the five factors, the relative plate width B/L, the relative wave height H/D, the wave steepness H/L, the relative plate spacing S/D and the relative depth d/D, the least square fitting method is used to give the calculation formula of the transmission coefficient and the total force of the vertical wave.
(2) the flow field structure and wave elimination mechanism around the double layer horizontal plate breakwater
Double horizontal plate to change water waves moving form. The flow structure around the specific performance of twin plate breakwater for submersible dike flow field between two plates in horizontal reciprocating flow, flow of the lower plate submerged embankment and embankment to the bottom of the reciprocating flow close to the level of the upper plate submerged breakwater. On the surface to the free surface, the lower plate on the surface of the embankment to the free surface vortex. Maximum vorticity with wave propagation and moving. Temporal and spatial variation of vortex intensity and shedding cycle and incident wave period, the flow field is determined by the changes of pressure change on the horizontal plate.
The influence on flow field of double horizontal plate breakwater in front of not more than 1 times the width of the flow field, a great influence on the embankment. Different positions of layered profile wave energy flow along the horizontal plate with uniform difference between double plate. Under the wave energy flux in submerged dike and dike embankment in the submersible and the lower plate. Reverse transfer can occur. The eddy energy loss and double plate where the water wave can flow reverse transfer is the main mechanism of wave absorbing double-layer plate breakwater.
(3) the wave elimination performance of double horizontal horizontal plate
The effect of breakwater wave and double horizontal plate, double horizontal plate plays (wave reflection and wave energy loss) and change the wave frequency of the dual role. Submerged dike and dike water after surface containing 2 and higher order harmonic components, especially when the relative width of less than 0.5, the high order harmonic occupy a larger proportion of energy components, under certain conditions can reach 1 order harmonic energy occupies a considerable proportion. So the transmission coefficient of the harmonic superposition of energy (2.5) definition is more reasonable. The coupling effect of the transmission coefficient is affected by many parameters, not double water plate is wide, the better the effect of wave dissipation monochromatic wave. In 0.29 ~ 0.72 times relative plate width range, the transmission coefficient is wave type changes with the relative plate width; the relative depth of d/D=-0.25 ~ +0.17 within the scope of the test, the relative effect of depth on the transmission coefficient is not very significant.
(4) on the wave pressure and its distribution
Wave pressure submerged embankment and embankment with 1 frequencies, 2 order, 3 order frequency is small, the other high frequencies can be ignored. Large difference of double horizontal plate with different stress position and pressure fluctuations, embankment upper plate is exposed on the surface, the pressure is very small, under the surface of the front and rear easy the impact pressure; the lower plate submerged embankment, showing the time-domain characteristics similar with submerged breakwater. But the submersible deep submerged dike, the lower end plate is prone to high frequency fluctuation pressure on the pressure wave envelope distribution, relative depth d/D, relative plate width of B/L and H/D on the relative wave height wave the pressure envelope influence the distribution, but the relative depth of d/D on the upper plate on the influence of wave pressure distribution under the surface of the upper plate, the upper surface of the submerged breakwater under wave pressure, and the pressure wave water levees are smaller; the upper plate under the embankment The surface of the submerged dike has no impact on the lower surface of the upper surface of the submerged dike.

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U656.2

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