Showing papers on "Breakwater published in 1979"

Design criteria for floating tire breakwaters

Abstract: Wave-transmission and peak-mooring force design curves were generated for the Goodyear and Wave-Guard floating tire breakwaters from measurements on ⅛-scale and ¼-scale models using regular and irregular waves, and found to be in good agreement with available full-scale data. These curves may be used to determine the breakwater size needed to attenuate a given regular design wave to an acceptable level, and also to determine the maximum mooring load associated with this. A simple semi-empirical energy-dissipation model was developed and found to simulate measured wave-transmission characteristics with sufficient precision to be useful in many engineering applications; e.g., the ratio of transmitted to incident wave height is stated as an exponential function of wave steepness, ratio of wavelength to breakwater-beam-size, breakwater porosity, and a drag coefficient. An empirical relationship for the peak mooring force was obtained.

Performance Analysis of Tethered Float Breakwater

Abstract: Describes laboratory experiments at one-half scale using simulated random seas and field tests at full scale of an installation of a dynamic floating breakwater system in a limited fetch situation. An analytical model is described which successfully predicted the performance of a tethered float breakwater configuration, given the incident wave spectrum. The methodology for selecting the arbitrary resistance coefficients in the predictive model is considered. Predicted and measured performance data for a total of 60 laboratory and field experiments are displayed, covering a very broad range of wave climates.

Diffraction of Waves by Shore-Connected Breakwater

Abstract: The diffraction diagrams commonly used by coastal engineers to determine the shelter afforded by a shore-connected breakwater are generally based upon Sommerfeld’s exact solution, with only limited experimental data to define the range of applicability. In order to establish this range more precisely, wave-height distributions in the shadow-zone of an impermeable shore-connected breakwater, 30-ft (9-m) in length, were measured in a large hydraulic-model basin and compared to Sommerfeld’s solution. The influence of a wave-splitter plate and energy dissipation on the structure were studied in experiments with the wave generator running continuously and also intermittently (stop-start). Detailed diffraction profiles were obtained both near the structure and at great distances, as far as 22 wavelengths from the breakwater. Long-crested regular waves were generated and found to be significantly non-uniform in height along the 65-ft (19.5-m) crest line under all conditions.

Tsunami atlas for the coasts of the United States

Abstract: Coastal power plant siting and safety analysis requires consideration of wave action and extreme water levels, both high and low. The run-up of large amplitude long waves, such as tsunamis, may pose a hazard to a coastal facility through direct dynamic effects on plant structures, through destruction of protective breakwaters and beaches, and the like. Extreme low water levels are of concern in design of coolant intake structures. The importance of tsunamis in these analyses, especially long Pacific coasts, makes specification of potential tsunami histories necessary. The present report addresses this problem. A large hypothetical earthquake is defined by appeal to history and tectonic theory. This canonical source serves as input to a numerical hydrodynamic model which computes the resulting wave history anywhere within the ocean basin. This procedure is repeated for a number of potential source locations, chosen according to degree and type of seismic activity. In this way, hypothetical coastal histories of great tsunamis emanating from any potential source area are simulated. The results of this study are offshore incident wave systems and do not include the complex, site-dependent, nearshore transformation. Users must account for such local effects in any specific application.

A new look at beach erosion control

Abstract: Many methods used previously to reduce or prevent erosion have not worked effectively. It isnow necessary, due to rising costs of construction, to examine old methods and see if Nature hasindicated some direction in which to go. Limitations of groins, seawalls and beach reclamation aredescribed. The most effective natural method of controlling beach erosion by the formation of anoffshore bar is described. The need for normal return of this material to the beach is met by the zetashaped bays sculptured between headlands by persistent swell waves. Man can copy Nature byinstalling offshore breakwaters in order to form stable bays along an eroding coast. The indentationof these is limited and is predictable from the obliquity of the waves or the angle between the down-coast shoreline and the headland alignment. This method has been used successfully in Singaporein spite of the extreme obliquity of the incident swell.

Development of the Ihi Floating Breakwater

Abstract: With the advent of the era of 200-mile economic sea zones, the efficient utilization of coastal waters has increasingly been required. Accordingly, many various facilities for cultivating marine products as well as port and harbor facilities, which used to be installed usually in shallow water of a bay, are obliged to be hereafter installed facing the open sea exposed to severe natural conditions. Under these circumstances, the development of the wave protection device to protect those facilities from high waves surging from the offing has come to be a pressing necessity. To meet the above requirements, IHI has recently developed the floating breakwater through various tank tests and bench tests of mooring parts. The designing techniques of this facilities have been developed based on accumulated field data, laboratory test data and theoretical analysis. Several field tests were conducted on the full-scale floating breakwater; as a result, the IHI floating breakwater proved to have excellent high ...

Determination of mooring load and transmitted wave height for a floating tire breakwater / by Michael L. Giles and James W. Eckert.

Abstract: Abstract : Floating tire breakwaters (FTB) are being used to protect and improve small-craft harbors, and as the need for additioal mooring space increases, FTB's are often being placed in locations exposed to larger waves. Other uses for FTB's include protection of construction operations, protection of dredges, and beach stabilization. Methods for predicting the transmitted wave height, as well as for determining the anchor loading for the Goodyear module FTB, are presented. These methods are based on laboratory tests that used full-scale monochromatic wave conditions typical of partially sheltered bodies of water. Wave transmission is given as a function of the ratio of the breakwater width to incident wavelength. The mooring load is also given as a function of incident wave height. Design curves and procedures are presented for determining the breakwater width required to obtain a desired degree of wave attenuation, and for determining the mooring loads for each anchor line. Various anchor types are discussed to aid in the design of an anchor system. (Author)

Development of table bay harbour

Abstract: This paper describes the physical model study of wave penetration and an investigation of harbor resonance in the existing and proposed lay-outs using a mathematical model. The results of the initial feasibility studies have suggested the use of an offshore breakwater to provide the necessary protection and navigability of two additional outer basins.