圆形沉箱防波堤波压力的试验分析

通过断面物理模型试验,获得了圆形沉箱结构直立堤在各种工况组合下,承受水平波压力、底部浮托力的大量数据信息。对这些数据进行了分析总结,得出了有关圆形沉箱直立堤波浪力的分布规律。     

Vibrating-Rocking Motion of Caisson Breakwater Under Breaking Wave Impact

The possible motions of a caisson breakwater under dynamic load excitation include vibrating, vibrating-sliding and vibrating-rocking motions. The models of vibrating motion and vibrating-sliding motion have been proposed in an early paper. In this paper, a model of vibrating-rocking motion of caisson breakwaters under breaking wave impact is presented, which can be used to simulate the histories of vibrating-rocking motion of caisson breakwaters. The effect of rocking motion on the displacement, rotation, sliding force and overturning moment of breakwaters is investigated. In case the overturning moment exceeds the stability moment of a caisson, the caisson may only rock. The caisson overturns only in case the rocking angle exceeds the critical angle. It is shown that the sliding force and overturning moment of breakwaters can be reduced effectively due to the rocking motion. It is proposed that some rocking motion should be allowed in breakwater design.     

Expected Sliding Distance of Vertical Slit Caisson Breakwater

Evaluating the expected sliding distance of a vertical slit caisson breakwater is proposed. Time history for the wave load to a vertical slit caisson is made. It consists of two impulsive wave pressures followed by a smooth sinusoidal pressure. In the numerical analysis, the sliding distance for an attack of single wave was shown and the expected sliding distance during 50 years was also presented. Those results were compared with a vertical front caisson breakwater without slit. It was concluded that the sliding distance of a vertical slit caisson may be over-estimated if the wave pressure on the caisson is evaluated without considering vertical slit.     

Numerical Simulation on Oscillation-Sliding-Uplift Rock Coupled Motion of Caisson Breakwater Under Wave Excitation

Corresponding to the sliding and the overturning failure, the elementary motion modes of caisson breakwater include the horizontal-rotational oscillation coupled motion, the horizontal sliding-rotational oscillation coupled motion, the horizontal vibrating-uplift rocking coupled motion, and the horizontal sliding- uplift rocking coupled motion. The motion mode of a caisson will transform from one to another depending on the wave forces and the motion behaviors of the caisson. The numerical models of four motion modes of caisson are developed, and the numerical simulation procedure for joint motion process of various modes of caisson breakwater under wave excitation is presented and tested by a physical model experiment. It is concluded that the simulation procedure is reliable and can be applied to the dynamic stability analysis of caisson breakwaters.     

Numerical Simulation on Oscillation-Sliding-Uplift Rock Coupled Motion of Caisson Breakwater Under Wave Excitation

Corresponding to the sliding and the overturning failure, the elementary motion modes of caisson breakwater include the horizontal-rotational oscillation coupled motion, the horizontal sliding-rotational oscillation coupled motion, the horizontal vibrating-uplift rocking coupled motion, and the horizontal sliding-uplift rocking coupled motion. The motion mode of a caisson will transform from one to another depending on the wave forces and the motion behaviors of the caisson. The numerical models of four motion modes of caisson are developed, and the numerical simulation procedure for joint motion process of various modes of caisson breakwater under wave excitation is presented and tested by a physical model experiment . It is concluded that the simulation procedure is reliable and can be applied to the dynamic stability analysis of caisson breakwaters.     

Numerical Simulation of Wave Interaction with Perforated Caisson Breakwaters

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Risk Analysis of Breakwater Caisson Under Wave Attack Using Load Surface Approximation

A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called load surfaces, which can be estimated as functions of wave height, water level, and so on. Then, the first-order reliability method（FORM） can be applied to determine the probability of failure under the wave action. In this way, the reliability analysis of breakwaters with uncertainties both in wave height and in water level is possible. Moreover, the uncertainty in wave breaking can be taken into account by considering a random variable for wave height ratio which relates the significant wave height to the maximum wave height. The proposed approach is applied numerically to the reliability analysis of caisson breakwater under wave attack that may undergo partial or full wave breaking.     

Model Study of Permeable Caisson Breakwater with Slanting Slabs

- This paper describes the design of a permeable caisson breakwater with slanting slabs (Types I and 11) and presents some preliminary experimental results, together with relevant figures and tables. Analysis is made of the reflection coefficient, transmission coefficient, acting wave pressures, water jetting at the crest of the breakwater, and wave overtopping. Experiments show conclusively that this type of breakwater has the advantages of light dead weight, good wave-absorbing performance, low coefficients of reflection and transmission, and small wave overtopping.     

Wave Forces on Submerged Semi-Circular Breakwater and Similar Structures

—The results of design and experiment of a submerged semi-circular breakwater at the Yangtzeestuary show that the submerged structure will be unsafe when the general empirical wave force formulafor semi-circular breakwater is used in design.Therefore,a new calculation method for the wave forces act-ing on a submerged semi-circular structure is given in this paper,in which the wave force acting on the in-side circumference of semi-circular arch is included,and the phase modification coefficient in the generalempirical formula is adjusted as well.The new wave force calculation method has been verified by the re-sults of seven related physical model tests and adopted in the design of the south esturary jetty of the firststage project of Deep Channel Improvement Project of the Yangtze River Estuary,the total jetty length be-ing 17.5km.     

Simulation of Wave Forces on A Semi-Circular Breakwater Using Multilayer Feed Forward Network

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Model Test Research of Breakwater Core Material Influence on Wave Propagation

The interaction between waves and porous breakwater has an important theoretical significance and great application value of engineering. In this paper, the tests of the core material’s influence in rubble mound breakwater on wave propagation are carried out. The relations among the transmitted wave height, incident wave element, and breakwater width are discussed. The calculation formula is obtained. The test results show that different core materials have obvious influence on wave propagation.     

Experimental Study on Ocean Internal Wave Force on Vertical Cylinders in Different Depths

A series of experimental studies about the force of internal solitary wave and internal periodic wave on vertical cylinders have been carried out in a two-dimensional layered internal wave flume. The internal solitary waves are produced by means of gravitational collapse at the layer thickness ratio of 0.2, and the internal periodic waves are produced with rocker-flap wave maker at the layer thickness ratio of 0.93. The wave parameters are obtained through dyeing photography. The vertical cylinders of the same size are arranged in different depths. The horizontal force on each cylinder is measured and the vertical distribution rules are researched. The internal wave heights are changed to study the impact of wave heights on the force. The results show that the horizontal force of concave type internal solitary wave on vertical cylinder in the upper-layer fluid has the same direction as the wave propagating, while it has an opposite direction in the lower-layer. The horizontal force is not evenly distributed in the lower fluid. And the force at different depths increases along with wave height. Internal solitary wave can produce an impact load on the entire pile. The horizontal force of internal periodic waves on the vertical cylinders is periodically changed at the frequency of waves. The direction of the force is opposite in the upper and lower layers, and the value is close. In the upper layer except the depth close to the interface, the force is evenly distributed; but it tends to decrease with the deeper depth in the lower layer. A periodic shear load can be produced on the entire pile by internal periodic waves, and it may cause fatigue damage to structures.     

斜向波对直立式防波堤堤头作用的试验研究

直立式防波堤堤头在斜向波浪作用下波浪力的计算在现行的技术规范中尚属空白。通过物理模型试验给出了堤头结构设计所需的波压分布图，指出了波浪入射方向和地形对堤头所受波浪力的贡献有时可以超过波高和波周期，根据现行规范按波浪正向入射计算堤头所受的波浪力偏于安全。     

带横隔板局部开孔沉箱在斜向波作用下的受力研究

基于线性势流假定,对斜向波作用下带横隔板局部开孔沉箱防波堤的水平波浪力进行了理论研究。给出了开孔沉箱法向水平力和横隔板受力的理论计算方法,在极限情况下波浪力的计算结果与文献中的已有结果一致。利用数值算例分析了开孔沉箱总水平力的主要影响因素。开孔沉箱法向总水平力的减小主要集中于结构上半部分波浪影响范围以内。增加单个开孔沉箱的长度有利于减小结构所受总水平波浪力。当波浪入射角或沉箱前开孔墙孔隙影响系数幅值较大时,开孔沉箱横隔板上总水平力的最大值要超过相应的沉箱法向总水平力,此时要注意横隔板的强度问题。     

Experimental Study on the Effects of A Breakwater on Wave Field Characteristics

Studies on the possible effects of a detached breakwater on the characteristics of the wavefield are carried out experimentally.A serpentine wave generator is used to generate both uni- andmulti-directional waves.Characteristics of the wave fields analyzed here include the wave fielddirectionality,and the probability distributions of surface elevations and of the wave heights.Owing to thepresence of the breakwater,waves outside the harbour are found to be reflected with,however,concen-trated energy within the harbour entrance.In general,wave heights can be approximated with a Rayleighdistribution,with occasional deviations from the theory.This occurs more frequently for waves with high-er peak frequency values than for those with lower values both for uni-and multi-directional waves.Sur-face elevations can be approximated with the Gaussian model.although the Edgeworth's form of the typeA Gram-Charlier series expansions would yield better fits.Wave directionality is found to have nodiscernible effects on     

斜坡堤胸墙波压力的试验与分析

通过断面物理模型试验,获得了斜坡堤堤顶胸墙在肩宽B不同工况组合下,承受水平波浪力、底部浮托力的大量数据。对这些数据进行了分析,得出了斜坡堤堤顶胸墙波压力随肩宽B的变化规律。     

Experimental Study of Wave Pressure on a Breakwater Pier

Test studies on the wave pressure on a breakwater pier show that the influence of transmissivewave pressure on the outside wall of the breakwater pier is considerable,when the width of the pier is notvery large.The variations of transmissive wave pressure on the breakwater pier with different widths arecompared and the relationship is obtained between relative transmitting distance b/L and wave pressurereduction factor K,which may be used in the design of similar breakwater piers.     

A Finite Element Solution of Wave Forces on Submerged Horizontal Circular Cylinders

In this paper, a numerical model is established for estimating the wave forces on a submerged horizontal circular cylinder. For predicting the wave motion, a set of two-dimensional Navier-Stokes equations is solved numerically with a finite element method. In order to track the moving non-linear wave surface boundary, the Navier-Stokes equations are discretized in a moving mesh system. After each computational time step, the mesh is modified according to the changed wave surface boundary. In order to stabilize the numerical procedure, a three-step finite element method is applied in the time integration. The water sloshing in a tank and wave propagation over a submerged bar are simulated for the first time to validate the present model. The computational results agree well with the analytical solution and the experimental data.Finally, the model is applied to the simulation of interaction between waves and a submerged horizontal circular cylinder.The effects of the KC number and the cylinder depth on the wave forces are studied.     

Experimental Investigation of Irregular Wave Uplift Force on Deck of Exposed High-Pile Jetties

A laboratory setup was developed to investigate irregular wave uplift loads on exposed high-pile jetties.It is shown that the dimensionless uplift load increases to the maximum with an increasing relative clearance and then decreases.The relative clearance corresponding to the peak force is linked to a range from 0.4 to 0.8.When the relative clearance exceeds a certain value,the wave can not reach the underside of the deck and the force becomes zero.Distinct trends of dimensionless force with a relative width of deck show that the force tends to decrease as the relative deck width increases,and then the decrease slows down after the relative deck width increases or decreases to a certain value.The pressure distribution length associated with the maximum uplift force is equivalent to the wave contact width x.When x is larger than the width of deck B,it is taken as B.The statistical distribution of loads obeys the Weibull distribution.The results from the analyses of the real data suggest a new dimensionless prediction model on wave-in-deck uplift loads and the conversion ratio between wave loads at different exceedance probabilities.A comparison is made between the new prediction model and the existing widely used three prediction models.These results are used as useful references for structural design of the jetty.