Showing papers on "Breakwater published in 1975"

Scrap tire shore protection structures

Abstract: Design manual for shore protection structures using old rubber tyres With the use of old car tires one may construct floating breakwaters and reef breakwaters

Floating Breakwaters-A Wave Tank Study

Abstract: As examples of the direct application of a floating breakwater, the author cities the desired protection of certain offshore operations, such as pipeline laying and tanker loading and unloading. This paper describes a laboratory study undertaken to establish which parameters affecting a breakwaters' performance are most important. Results show that wave reduction was not greatly affected by wave height. With regard to the breakwater itself, a square cross-section gives slightly better wave reduction than a triangular, circular, or trapeziodal one. Permeable and impermeable coverings give essentially the same results. Concentrating the ballast low in the profile and using two-thirds to full submergence yielded best results. As indicated by the author, probably one of the most serious and least understood problems is that of the mooring of breakwaters. The result of this study indicates that mooring line forces can be reduced by using horizontal lines and by the proper choice of attachment point.

Investigation, Design and Construction of a Harbour on King Island, Tasmania

Abstract: A small but fully equipped artificial harbour has been constructed at Grassy on the exposed south-east coast of King Island, Bass Strait. Twenty-six months after instructions were received to commence investigations and prepare designs, the port was commissioned with the commencement of a roll-on roll-off shipping service to the island in May 1972. The port is now in full use as a commercial coastal terminal. The principal feature of the project was construction of a 600 m breakwater in depths to -18 m extending from a rocky promontory to an offshore island which provides a natural roundhead. Very large quantities of limited size rock were readily available from open-cut scheelite mining operations and were utilised in a carefully phased construction sequence. By mass dumping of large quantities of rock it was possible to avoid conventional heavy construction methods requiring progressive protection of the advancing breakwater head against wave action. Consolidation of the mound by the sea was encouraged before armouring was applied with the intention of achieving a stable beach of wave breakers on an anticipated ultimate slope of approximately 1 : 10. Breakwater construction was carried out using only mining equipment, the whole being integrated with the mining operation.

Disasters of breakwaters by wave action (2)

Abstract: Some 63 breakwaters damaged by wave action have been restored between 1965 and 1972. Comparative data are presented for 63 examples in 49 harbors where some damage to the actual caissons was noted, encompassing caisson breakwaters damaged during construction to those finished at least with a concrete covering. Diagrams show the breakwaters before damage was sustained, the damage condition, and the restored cross section. Simple analyses are attempted on the total number of breakwaters damaged between 1965 and 1972 to clarify and trends in breakwater damage. (Author)

Scour at End of Breakwater with Oblique Incident Waves

Abstract: Observations of grain suspension and deep scour hole at the tip of a breakwater show that the line vortices play an important role in this scour process. For clarifying the scour mechanism, the pertinent features of the wave form along the breakwater are discussed. A review of the relevant parameters is given for relating the wave characteristics to vortex strength, and hence scour depth. To simulate the complexity of the flow field near the tip of the breakwater, it is proposed to oscillate the breakwater head in a flume with motions similar to water particle oscillations produced by waves in that location.

TFB: A transportable open ocean breakwater

Abstract: The paper describes a unique floating breakwater under joint development by California and the Navy. The transportability of the system makes it applicable for temporary protection of offshore construction projects, as well as for a number of permanent installations where conventional breakwaters are not feasible. The results of the development program are described, including the successful demonstration of a limited fetch breakwater in San Diego Bay. Plans for an ocean scale experiment during the next year are outlined. Recommendations are presented for the commercial development of the system to meet national needs-both commercial and military.