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Saturday, July 18, 2020 | History

4 edition of Breakwaters protected with dolosse found in the catalog.

Breakwaters protected with dolosse

J. A. Zwamborn

Breakwaters protected with dolosse

by J. A. Zwamborn

  • 228 Want to read
  • 40 Currently reading

Published by Coastal Engineering and Hydraulics Division, National Research Institute for Oceanology, Council for Scientific and Industrial Research in Stellenbosch, South Africa .
Written in English

    Subjects:
  • Breakwaters -- Design and construction.,
  • Waves.

  • Edition Notes

    Bibliography: leaves [12]-[13]

    Other titlesDolosse.
    Statementby J.A. Zwamborn.
    SeriesCSIR report., 7920
    Classifications
    LC ClassificationsTC333 .Z8 1979
    The Physical Object
    Pagination11, [2] leaves ;
    Number of Pages11
    ID Numbers
    Open LibraryOL4171499M
    ISBN 100798815590
    LC Control Number80154458
    OCLC/WorldCa9827119

    Contact us today to learn more about breakwaters and shoreline protection. Tetrapod. Tetrapod in coastal marine applications, is an interlocking four-legged armour unit designed to protect breakwaters and shorelines. The shape helps dissipate the force of the waves by causing the waves to go around the unit. The Tetrapod is placed randomly and. structures (Markle and Davidson, in preparation) protected with concrete armor units and experimental tests of dolos-armored, breakwater trunk sections (IV-on-l.5H slopes) subjected to both breaking and nonbreaking waves should be initiated on breakwaters with broken dolosse. The purpose of the,*.

    A breakwater is a man-made wall that breaks up big waves, reducing damage to the shoreline and nearby marina. The objects' shape works to break up waves under the water, said Gina Lathan of. A total of nine breakwaters along Lake Erie became official Superstorm Sandy projects for the U.S. Army Corps of Engineers, Buffalo District. Underneath the dolosse was placed approximately.

      Breakwaters reduce the intensity of wave action in inshore waters and thereby provide safe harbourage. Breakwaters may also be small structures designed to protect a gently sloping beach to reduce coastal erosion; they are placed – feet (30–90 m) offshore in relatively shallow water.. An anchorage is only safe if ships anchored there are protected from the force of powerful waves by Missing: dolosse. The breakwaters are rubble mound constructions with dolosse serving as armour protection. The main (eastern) breakwater is the longest in South Africa. The breakwaters and dolosse were constructed and placed from September to February The crest of the breakwaters at the Port of Ngqura has been formed by 26, ton dolosse.


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Breakwaters protected with dolosse by J. A. Zwamborn Download PDF EPUB FB2

A more robust design for the repair was implemented using precast, ton geometric concrete blocks known as dolosse."A total of 3, linear feet of breakwater will be repaired using dolosse. Effect of Broken Dolosse on Breakwater Stability Trends in Stability of Dynamically Stable Breakwaters.

Coastal Engineering December Breakwater Stability – Breaking Wave Data ASCE Subject Headings: Breakwaters, Coastal protection structures, Coastal environment Conference Information. A dolos is a reinforced concrete block in a complex geometric shape weighing up to 80 tonnes, used in great numbers as a form of coastal management to build revetments for protection against the erosive force of waves from a body of water.

The dolos was invented inand was first deployed in on the breakwater of East London, a South African port city.

Thus 18 dolosse on the south jetty and 22 dolosse on the north jetty will be monitored* At least one permanent survey point will be established on each of the selected dolosse. By using existing horizontal and vertical control established for project construction, the x, y, and z coordinates of each selected survey point will be determined.

While ports are gateways to the country’s transport networks, breakwaters protect port entrance channels, into and out of the ports (Figure 1). The entrances to most of the ports in South Africa are protected by rubble mound breakwaters which have dolos armouring.

To put the size of the Cleveland East dolosse breakwater project into perspective, the required repairs involved the placement of o dolosse, each weighing tons.

Underneath the dolosse was placed approximat tons of bedding stone, each weighing two to five hundred pounds tons of underlayer stone, each weighing. Offshore breakwaters are walls built parallel to the shoreline but at some distance offshore, typically a few tens of meters seaward of the normal surf zone.

These structures dampen the wave energy on the ‘protected’ shoreline behind the breakwater, interrupting the longshore current and causing sand to be deposited and a beach to g: dolosse.

In Kahuluie, Hawaii, the breakwater which was built with heavy armour stone had to be rebuilt using Tetrapods after it was badly damaged.

When the Tetrapods were destroyed by storms it was then rebuilt with Tribar armour units and, when these were washed away the present structure was protected by Dolosse (Harlow, ). Rubble mound breakwaters are often constructed in layers, to ensure the integration of the strengths of different materials.

For instance, layers made by fine sediments may be used to reduce the permeability of the structure, but then they should be protected by wave action with a. Breakwaters reduce the intensity of wave action in inshore waters and thereby provide safe harbourage. Breakwaters may also be small structures designed to protect a gently sloping beach to reduce coastal erosion; they are placed – feet (30–90 m) offshore in relatively shallow water.

An anchorage is only safe if ships anchored there are protected from the force of powerful waves by Missing: dolosse. The paper deals with two-dimensional tests on a scale model of a dolos breakwater. It is related with the construction of a large harbour at Sines for tankers with up to 1 million dwt, ore ships with up todwt, general cargo, etc.

DOLOS USE They are used to protect harbor walls, breakwaters, and shore earthworks. They are also used to bind sea-sand to prevent erosion.

In the order of 10 dolosse are required for a kilometer of coastline. They work by dissipating, rather than blocking, the energy of waves. Dolosse are in use across the world, either in their original shape or in variations but following similar principals.

They can be found reinforcing the breakwaters of ports. Results showing significant fatigue from impact tests with Dolosse made of unreinforced and steel fibre reinforced flyash concrete are presented.

Moreover universal graphs for fatigue in armour units made of conventional unreinforced concrete exposed to impact load and pulsating load are presented.

The eight harbours, where the breakwaters are regularly monitored, are spread out along the east and south coast of South Africa, from Richards Bay in the north-east to Cape Town and Saldanha Bay in the south-west. All but one of these ports are protected by rubble mound breakwaters, which are covered with Dolos armour units.

The Dolos, a new type of armour unit which closely resembles a normal ship's anchor, was developed and tried out under field conditions on the main breakwater of East London harbour. Since these full-scale Dolosse proved very successful, tests were made in a wave channel to compare the stability of Dolosse with other known types of armour blocks.

MR T. S0RENSEN and MR 0. JENSEN In connection with the question about whether breakwaters subjected to model tests fail as often as breakwaters designed without model tests, the case of Torshavn Harbour is interesting.

In this case a direct comparison of the model and the prototype was possible and a close agreement was found. Emerged breakwaters cannot be constructed in the form of long continuous structures without gaps (Pinto and Neves, ).

The gaps between the barriers are necessary in the emergent breakwaters for continuous water exchange between the protected area and shoreside, but often produce rip currents, bed irregularities and tombolos (Pilarczyk, ). Coastal Eng., 8: A new empirical stability criterion for dolos-armoured, rubble-mound breakwaters is proposed.

This criterion is based on an analysis of the energy level at which dolos armour units fracture and break in a breakwater environment. The input information has been obtained from ten different prototype breakwaters. Recently, structural measurements in dolosse and field surveys of concrete-armored breakwaters have provided new insight into armor unit response.

The research reinforces previous conclusions that most breakage occurs due to impacts between moving units and that the central sections of dolosse and tribar are too slender to resist these impact. Extensive use was made of dolosse (branching concrete blocks weighing up to 30 tons) to construct the two breakwaters ( meters long in total) protecting the harbour entrance.

The dolos is a South African invention in which interlocking blocks of concrete .Stability equations for high-crested berm breakwaters Stability equations for low-crested, emerged breakwaters and groins Stability equations for submerged breakwaters Stability equations for toe protection of breakwaters Stability equations for rear side of breakwaters.

“Dolosse are used on the Humboldt, California jetties; the Manasquan Inlet, New Jersey jetties, and on several Hawaiian breakwaters – to name just a few. The dolosse invention is anchored by the historic casting of the biggest dolosse on the African continent for the deepwater Port of Ngqura outside Port Elizabeth.