408 research outputs found
North-coast of Texel: a comparison between reality and prediction
No full textFor an efficient protection of the north coast of the Dutch Waddensea island Texel, a long dam was constructed in 1995. The position of this dam is on the southern swash platform of the ebb tidal delta of the Eijerlandse Gat: the tidal inlet between the two Waddensea islands Texel and Vlieland. The long dam changed the hydro-morphological conditions in this tidal inlet. The changes in the inlet's morphology have been monitored through regular bathymetry surveys. This paper describes some of the most remarkable changes that occurred in the inlet after the construction of the long dam. The impact of the long dam on the inlet's morphology and the adjacent shoreline stability has been examined with the use of a medium-term morphodynamic model. From a comparison between the observed and predicted morphological changes it followed that the model was able to simulate the large scale morphological response of the inlet system. However, on a smaller scale there were still important discrepancies between the observations and the predictions
Wave spectra transformations
No full textIn this paper the transformations of sea waves, reproduced by a JONSWAP spectrum in a laboratory channel, have been studied both in frequency and time domain. In frequency domain the occurrence of non-linearities producing energy transfers to high and low frequencies was studied. The reported experimental results enabled us to comparate the two approaches and to define the limits within which they give the same results
Evolution of a beach with and without a submerged breakwater: experimental investigation
No full textIn the present report experimental results about the efficiency of a submerged structure are presented. The experiment, carried out with random waves, covered about 2500 hours until equilibrium profile was reached. The most significant results are the good behaviour of the tested breakwater as a sand holding structure and its slowing effect produced on the shoreline backing, whereas the final position of the shoreline was nearly the same with and whithout breakwater
Durability and Testing of Stone for use in Rubblemound structures
No full textRubblemound structures protected from wave action by a layer of quarried rock (stones) are the most common form of breakwaters. While extensive guidelines and procedures exist to select the size of stone there is very little information available on procedures to be followed to assure the quality of the in-place stone
Edge waves and resonance on elastic structures: An overview
No full textCopyright @ 2011 SAGE PublicationsOver 50 years have elapsed since the first experimental observations of dynamic edge phenomena on elastic structures, yet the topic remains a diverse and vibrant source of research activity. This article provides a focused history and overview of such phenomena with a particular emphasis on structures such as strips, rods, plates and shells. Within this context, some of the recent research highlights are discussed and the contents of this special issue of Mathematics and Mechanics of Solids on dynamical edge phenomena are introduced
Can we predict the growth of sandwaves? Hindcast of a field experiment in the Bisanseto Sea Japan
No full textTo optimise the dredging of sand waves in navigation channels, it is important to predict the regeneration of the sand waves. For this purpose, the authors combine a morphodynamic evolution model, based on the Landau equation, with data measured in a field experiment in the Bisanseto sea in Japan. A good agreement is found between the measurements and the model result. Therefore, the combination of the Landau model and a genetic algorithm, proves to be a useful tool for the maintenance of navigation channels through a sand wave fiel
Stresses in Dolosse
No full textFailures of rubble mound breakwaters armoured with complex types of unreinforced concrete armour units are often due to breakage. This happens when the stresses exceed the material strength. Sufficient parametric studies of the stresses are not yet available to produce design diagrams for structural integrity. The paper presents the results and the analyses of model tests with 200 kg and 200 g load-cell instrumented Dolosse. Static stresses and wave generated stresses were studied as well as model and scale effects. A preliminary design diagram for Dolosse is presented as well
Estimation of Peak Wave Stresses in Slender Complex Concrete Armor Units
No full textRecent methods for the structural design of concrete armor units divide the forces into static loads, impact loads, and wave or pulsating loads. Physical model technology is being developed at several laboratories to measure wave loads on model armor units. While this technology represents significant progress, structural designers require a maximum stress value to design armor units
HURRICANE INDUCED WAVE AND SURGE FORCES ON BRIDGE DECKS
No full textThe damaging effects of hurricane landfall on US coastal bridges have been studied using physical model testing. Hurricane bridge damage and failure susceptibility has become very evident, especially during hurricane seasons 2004 and 2005 in the Gulf of Mexico. The combination of storm surge and high waves caused by a hurricane can produce substantial loads on bridge decks leading to complete bridge failure. Several theoretical methods have been developed to estimate these forces but have not been tested in a laboratory setting for a typical bridge section. Experiments were done using a large-scale 3-D wave basin located at the Haynes Coastal Engineering Laboratory at Texas A&M University to provide estimates of the horizontal and vertical forces for several conditions to compare with the forces predicted with the existing models. The wave force results show no strong correlation between the actual force measured and the predicted force of existing theoretical methods. A new method is derived from the existing theoretical methods. This model shows a strong correlation with both the measured horizontal and vertical forces
Reliability Based Optimal Design of Vertical Breakwaters Modelled as a Series System Failure
No full textReliability based design of monolithic vertical breakwaters is considered. Probabilistic models of important failure modes such as sliding and rupture failure in the rubble mound and the subsoil are described. Characterisation of the relevant stochastic parameters are presented, and relevant design variables are identified and an optimal system reliability formulation is presented. An illustrative example is given
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