Showing papers on "Breakwater published in 1970"
TL;DR: In this article, an experimental study of the piling-up phenomenon behind low and submerged breakwaters is presented, where the authors found that the relative height of piling up is a function of the relative depth of submergence, or of the depth of protrusion of the breakwaters.
Abstract: An experimental study of the phenomenon of piling-up behind low and submerged breakwater is presented. Piling-up occurs in completely enclosed areas or behind two-dimensional breakwaters as a result of overtopping of the breakwater. The water that spills into the protected area is accumulated there until the mean water level inside the protected area is higher than the man sea level outside. This difference in elevation, or height of piling-up, reaches eventually a value sufficient to cause a mean outflow of water through and above the breakwater equal to the mean inflow by water overtopping the structure and spilling into protected area. For a given breakwater and mean sea level, the height of piling-up was found to be an increasing function of the height of the waves in the deep sea. Expressing values relative to this wave height, the relative height of piling-up was found to be a function of the relative depth of submergence, or of the relative height of protrusion of the breakwaters. The maximum value of piling-up for the structures tested was found to be of the order of 60% of the wave height. Values of this magnitude were found for low breakwaters with crest elevations above mean sea level of between 50% and 90% of the wave height.
47 citations
12 citations
TL;DR: In this paper, the function of Tsunami breakwaters is discussed. But this paper is limited to the case of tsunami breakwaters and is not suitable for other types of breakwaters.
Abstract: (1970). On the Function of Tsunami Breakwaters. Coastal Engineering in Japan: Vol. 13, No. 1, pp. 103-112.
10 citations
TL;DR: In this article, the effect of Tsunami-breakwater breakwater on coastal engineering in Japan is discussed. But they focus on the effects of breakwaters on the sea surface.
Abstract: (1970). On the Effect of Tsunami-Breakwater. Coastal Engineering in Japan: Vol. 13, No. 1, pp. 89-102.
10 citations
TL;DR: In this article, the authors used a shallow water wave computation model coupled with a simple procedure aimed at evaluating bed load transport potential to provide a measure of the stability of a given bottom configuration, while unable to produce a simulation of the actual bottom evolution.
Abstract: Beach replenishment in the presence of a submerged barrier has become a popular strategy in some countries, both as a coastal protection system and as a means to protect or increase recreational beach activities. Whether the submerged barrier is meant as a proper breakwater system which reduces the wave energy or only as a way to retain the fill, its effects on both the wave hydrodynamic regime and the sediment transport are extremely important and complex. Research in this field has been very active in the last few years, but no definitive solution has yet been found to correctly design perched beaches; the recent advances in the numerical simulation of cross shore transport processes, however, have improved the possibility of understanding the behaviour of these structures. The paper reports on the results obtained by making use of a shallow water wave computation model coupled with a simple procedure aimed at evaluating bed load transport potential; this approach, while unable to produce a simulation of the actual bottom evolution, provides a measure of the stability of a given bottom configuration.
8 citations
TL;DR: In this article, an L-shaped chamber is proposed for minimizing the energy content of wind waves reflected from a floating bridge, where a linearized differential equation describing the hydraulics of the system has the form of a forced, damped oscillator; here, the term analogous to the natural frequency contains the key dimensions of the breakwater and an added mass.
Abstract: One method proposed for minimizing the energy content of wind waves reflected from a floating bridge incorporates an L-shaped chamber as a structural part of the bridge. The basic chamber has a vertical leg perforated with circular holes, the bottom is solid. A linearized differential equation describing the hydraulics of the system has the form of a forced, damped oscillator; here, the term analogous to the natural frequency contains the key dimensions of the breakwater and an “added mass” term. Solutions show the quantitative dependence of reflection coefficient upon the ratio of wave frequency to system (natural) frequency, wave camber, wall porosity, and chamber dimensions. The breakwater is most efficient (reflection coefficient as low as 0.2) when the frequency of the incident wave is near the system frequency, which provides a design link between incident wave and optimum breakwater dimensions. A prototype design example is included.
8 citations
TL;DR: In this paper, some general properties on the change of the topography of sea-bed caused by the construction of breakwaters are discussed on the basis of the hydraulic sounding maps of several ports and the results of model tests.
Abstract: In Japan, many breakwaters or jetties have been constructed in the sandy beach from the past decade for new ports to cope with the development of industry It is needless to say that the construction and prolongation of breakwaters or jetties cause the change of bottom topography in their vicinity, but many points remain indistinct on this change of bottom-topography In this paper, some general properties on the change of the topography of sea-bed caused by the construction of breakwaters are discussed on the basis of the hydraulic sounding maps of several ports and the results of model tests The terminology used in this paper is given in Figure 1.
7 citations
TL;DR: The concept of multiple use of reservoirs is resulting in the construction of marinas for recreational boating requiring breakwaters that can function for a large range of water levels as mentioned in this paper, a typical set of design criteria is an average water depth of 20 to 25 feet, wave lengths from S to 60 feet (wave periods of from 1 to 4 seconds) and wave heights from J to 5 feet Calculations based on Bulson's results showed a pneumatic breakwater to be too expensive.
7 citations
01 Jan 1970
TL;DR: The basic component of this breakwater consists of used truck tires some of which are filled with flotation material such as polystyrene, polyurethane, plastic bottles, inner tubes, or other material which will provide flotation.
Abstract: The basic component of this breakwater consists of used truck tires some of which are filled with flotation material such as polystyrene, polyurethane, plastic bottles, inner tubes, or other material which will provide flotation. The construction consists of a top horizontal diaphragm of truck tires bolted to a center sandwich of vertical tires arranged in a triangular pattern. The breakwater should be constructed so that the width is approximately the length of the wave to be attenuated.
6 citations
TL;DR: In this paper, the performance of a traditional rectangular caisson floating breakwater with a horizontal top has been improved by using a design with a sloping top and two rows of energy-dissipating porous sheets installed underneath the caisson.
Abstract: This paper examines concrete caisson floating breakwaters designed by Bourgon Lafleur Inc., St. Polycarpe, Quebec. The performance of a traditional rectangular caisson floating breakwater with a horizontal top has been improved by using a design with a sloping top and two rows of energy-dissipating porous sheets installed underneath the caisson.
TL;DR: In this article, the use of asphalt in breakwater construction has proved feasible and several cross-sections based on this concept were sub-ected to model tests to compare their behaviour under wave-attack with that of conventional crosssections.
29 Jan 1970
TL;DR: In this article, experimental data are given to aid in the design of a rubble-mound breakwater and the use of armor damage functions is supported rather than use of the wave height for the no damage condition.
Abstract: In this paper experimental data are given to aid in the design of a rubble-mound breakwater The use of armor damage functions is supported rather than the use of the wave height for the no damage condition Damage curves defined experimentally are proposed, for both rocks and tetrapods, for different wave storm durations and for different placing tech niques A determinant influence of storm duration is found for advanced damage of the armor layers The experiments with different placing techniques showed that stability coefficients based upon the no damage criteria, do not give a reliable picture of the ultimace strength of a rubble-mound breakwater.
01 Jan 1970
TL;DR: In this paper, an L-shaped chamber is proposed for minimizing the energy content of wind waves reflected from a floating bridge, where a linearized differential equation describing the hydraulics of the system has the form of a forced, damped oscillator; here, the term analogous to the natural frequency contains the key dimensions of the breakwater and an added mass.
Abstract: One method proposed for minimizing the energy content of wind waves reflected from a floating bridge incorporates an L-shaped chamber as a structural part of the bridge. The basic chamber has a vertical leg perforated with circular holes, the bottom is solid. A linearized differential equation describing the hydraulics of the system has the form of a forced, damped oscillator; here, the term analogous to the natural frequency contains the key dimensions of the breakwater and an “added mass” term. Solutions show the quantitative dependence of reflection coefficient upon the ratio of wave frequency to system (natural) frequency, wave camber, wall porosity, and chamber dimensions. The breakwater is most efficient (reflection coefficient as low as 0.2) when the frequency of the incident wave is near the system frequency, which provides a design link between incident wave and optimum breakwater dimensions. A prototype design example is included.
29 Jan 1970
TL;DR: In this paper, a digital computer model for diffraction of wind waves behind a breakwater is developed, which combines the hydrodynamic theories and the concept of directional spectra and is designed so that it may be used not only for the study of the wind wave diffraction problem behind breakwaters but also for the investigation of experimental (or field) data analysis procedures of other kinds.
Abstract: A digital computer model for diffraction of wind waves behind a breakwater is developed The model combines the hydrodynamic theories and the concept of directional spectra It is designed so that it may be used not only for the study of the wind wave diffraction problem behind breakwaters but also for the investigation of experimental (or field) data analysis procedures of other kinds An extensive study of optimum data length, lag number and gage spacings m wave gage arrays is presented.
TL;DR: In this paper, the minimum required widths of a concrete vertical wall breakwater with respect to the stability criteria of overturning, sliding and settling are presented in the case where the breakwater is built on a foundation and located in the conditions for nonovertopping and overtopping by incident waves.
Abstract: The calculation of the minimum required widths of a concrete vertical wall breakwater with respect to the stability criteria of overturning, sliding and settling is presented in the paper. It is assumed that the vertical wall breakwater is built on a foundation and located in the conditions for non-overtopping and overtopping by incident waves. In the analysis of wave forces on the vertical wall breakwater a distinction is made between the action of nonbreaking, breaking and broken waves. The disturbing nonbreaking wave forces are calculated using Sainflou's and Molitor's methods. The breaking wave forces are calculated according to the method developed by Minikin, and the broken wave forces according to the method proposed by the CERC (Coastal Engineering Research Center). Using the derived expressions and appropriate values of the safety factor for overturning and sliding, and allowable normal stress of the foundation for settling, and applying the assumed environmental conditions, it is possible to determine directly the minimum required width of a vertical wall breakwater. A numerical example in which the minimum required widths of a vertical wall breakwater in different wave load conditions are calculated according to the analyzed stability criteria is also given in the paper.