Showing papers on "Breakwater published in 1971"

Armor Stability of Overtopped Breakwater

Abstract: Model tests were performed to assist the selection of stable armor sizes for the Pilgrim Nuclear Power Station breakwaters. Tests were performed on typical breakwater trunk and head sections under breaking wave conditions. The study indicated that for each armor zone there is a particular water depth at which maximum damage to that armor zone will occur. For upper level armor this water depth was less than the maximum design water stage, indicating that maximum damage to the breakwater armor will not necessarily occur under the maximum wave heights possible. The slope of the leeside was also found to be of significance for stability of armor in upper levels. More comprehensive model investigations may show that it is possible to apply existing empirical formulas for nonovertopped breakwaters to overtopped conditions, provided that an appropriate critical still water depth is used for each armor zone, and consideration is given to the leeside slope.

Floating breakwater for attenuating seas

Abstract: A floating breakwater for attenuating seas which has two or more expanding portions so disposed as for each to be increasingly enlarged in size increasingly, in turn, from the front to the rear and disposed against the propagation of sea waves.

Field study of wave transmission through a rubble-mound breakwater

Abstract: Characteristics of sea and swell incident at a permeable rubblemound breakwater located in Monterey Harbor, California, are resolved into reflected and transmitted components. The wave characteristics are studied by analyzing synchronized wave records of three underwater sensors judiciously placed, two to seaward and one to landward of the breakwater. Power spectra and cross spectra are calculated for various characteristic sea states selected from three months of observations. Amplitude and phase are determined for the spectral wave components comprising the partial standing wave phenomena. This study was unique in that it entails experiments conducted in the field on a prototype structure in the natural environment. Transmission has been studied heretofore exclusively with scale models. The coefficients of transmission are considerably less for the prototype than predicted by a Corps of Engineers model study of the Monterey Breakwater. The differences are apparently related to more wave energy scattering and dissipation due to turbulence than predicted by the model.

Irregular Wave Action on Rubble-Mound Breakwaters

Abstract: An investigation was undertaken to compare the effect of regular and irregular waves on a rubble-mound breakwater model. During the experiments water depth, breakwater, and wave characteristics were kept constant; wave heights were varied. Experiments were conducted to determine the damage in terms of the displaced number of stones. It was concluded that the damage on a rubble-mound break-water is related to the energy of the attacking wave. Experiments revealed that relating the damage to the total energy is inaccurate. Consequently, this concept was replaced by a relationship between the damage and the effective energy, which is the part of the energy including the energy of waves higher than the design wave. Therefore, it was shown experimentally that the effective energy determines the different the different effects of regular and irregular wave action on the breakwater. It was shown that regular waves have the same effect as the irregular waves when the significant wave heights equal the heights of regular waves.

On the Function of Tsunami Breakwaters: (Report No. 2)

Abstract: (1971). On the Function of Tsunami Breakwaters: (Report No. 2) Coastal Engineering in Japan: Vol. 14, No. 1, pp. 63-72.

Stability tests on a rubble mound breakwater head in regular and irregular waves. sorvaer fishing port, norway

Abstract: Results from a two-dimensional case study carried out at RHL showed that irregular waves seemed to represent a more severe wave attack than regular waves with heights equal to the significant wave heights of the irregular wave. It was further concluded that the factors that influence the stability of a breakwater are many and complex and vary within wide ranges from project to project. The best basis for breakwater design is still model testing, preferably with irregular waves. This conclusion was also positively underlined by van Oorschot. In view of these conclusions a case study has been carried out at RHL regarding the stability of the head of the rubble mound breakwater under construction at the fishing port of Sorvaer in the northernmost county Finnmark of Norway. The sponsor of the tests was the Norwegian State Harbour Works. The study involved evaluation of the design wave height from meteorological data as well as model testing. The evaluation of the design wave height followed more or less standard procedures, the presentation of which is of less general interest. The tests involved intensive investigations of the breakwater stability in regular waves as well as in irregular waves. It is the latter tests that are considered to be of most general interest and which are reported in this paper. The following conclusions were drawn from the tests results: 1. The stability of the armour layer seems to be the same in regular and irregular waves when the significant wave heights of the irregular wavetrain correspond to the height of the regular waves. 2. The two long terms indicated a breakdown for lower waves than in the other tests. However, since only two such tests were run, no definite conclusions can be drawn on this point. 3. Regarding erosion on the foot berm this seemed in some cases to be the same in regular and irregular waves. The tests indicated that the erosion was larger with irregular waves than with regular waves when the waveheights were just above the waveheight when erosion started. At larger waveheights the erosion tended to be approximately the same for regular and irregular waves. None of the tests showed damage to the armour layer due to erosion of the foot berm.

Diffraction of wind generated waves by a breakwater gap

Abstract: Hydraulic laboratory experiments were made of the diffraction of wind generated waves by a breakwater gap. Directional spectra of the incident wave was used together with the water wave diffraction theory of Penny and Price for a breakwater gap, to predict the energy spectral density and the measured values demonstrated the limits of using the above techniques. It is likely that this is due to the inadequacy of the diffraction theory of Penny and Price for a breakwater gap for certain ranges of B/L. The report contains listings of six FORTRAN computer programs used to support the research. (Author)

A discussion of the results of some laboratory tests on breakwater armour units

Abstract: During 1969-70 some laboratory tests were completed for the Department of Public Works at Laval University, Quebec City. The aim of the program was to compare the efficiency of Dolos, Tetrapod and quarry stone armour units. A model breakwater was constructed to a linear scale of 1:16 and tests were completed with regular and irregular waves. The results of these tests are discussed and comments are made on the implications of graphs showing incident wave height versus damage curves in standard design procedures for rubble mound breakwaters, particularly in depths of less than 40 feet or so. A review of the literature describing similar tests suggests that there is a need for agreement on the definition of damage and on some uniformity of data presentation. The effect of storm duration, the stability of units on the breakwater facing and the need for control during placing of the units is discussed.