Showing papers on "Breakwater published in 1987"
TL;DR: The construction of detached breakwaters is one of the main countermeasures against beach erosion in Japan and the number of breakwaters has been rapidly increasing, with about 2500 constructed as of 2010.
Abstract: Construction of detached breakwaters is one of the main countermeasures against beach erosion in Japan. The number of breakwaters has been rapidly increasing, with about 2500 constructed as...
34 citations
01 Jan 1987
TL;DR: In this article, the stability of a berm type breakwater was tested in a 3D model at The Hydraulics laboratory, Department of Civil Engineering, University of Aalborg.
Abstract: The stability of a berm type breakwater (sacrificial breakwater) was tested in a 3-dimensional model at The Hydraulics laboratory, Department of Civil Engineering, University of Aalborg. The object was to study the stability/erosion of the breakwater head and the trunk, the latter exposed to both head-on and oblique irregular waves. To avoid too many parameters a simple breakwater geometry and only one class of stones were used. The roundhead erosion and the erosion of the trunk in oblique waves have a very strong non-linear dependency on the sea state. Below a certain sea state threshold value the erosion rates are very small, but excess of this value causes a drastic increase in the erosion. Consequently identification and consideration of this threshold value are of great importance in the design process.
10 citations
01 Jan 1987
TL;DR: In this paper, the authors proposed a take down policy to remove access to the work immediately and investigate the claim that this document breaches copyright, and they provided details of the claim.
Abstract: ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research. ? You may not further distribute the material or use it for any profit-making activity or commercial gain ? You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access to the work immediately and investigate your claim.
9 citations
01 Jan 1987
TL;DR: In this article, the stability of a berm type breakwater was tested in a 3D model at The Hydraulics laboratory, Department of Civil Engineering, University of Aalborg.
Abstract: The stability of a berm type breakwater (sacrificial breakwater) was tested in a 3-dimensional model at The Hydraulics laboratory, Department of Civil Engineering, University of Aalborg. The object was to study the stability/erosion of the breakwater head and the trunk, the latter exposed to both head-on and oblique irregular waves. To avoid too many parameters a simple breakwater geometry and only one class of stones were used. The roundhead erosion and the erosion of the trunk in oblique waves have a very strong non-linear dependency on the sea state. Below a certain sea state threshold value the erosion rates are very small, but excess of this value causes a drastic increase in the erosion. Consequently identification and consideration of this threshold value are of great importance in the design process.
6 citations
TL;DR: In this article, a systematic procedure is proposed for estimating the economic losses with and without breakwater protection along with the first and maintenance costs for a set of alternatives with varying functional performance and structural integrity design criteria.
Abstract: The cost-effective optimization of rubble-mound breakwater cross sections requires a summation of all the life cycle costs for each alternative design, including construction costs, maintenance costs and associated economic losses due to wave attack. A systematic procedure is proposed for estimating the economic losses with and without breakwater protection along with the first and maintenance costs for a set of alternatives with varying functional performance and structural integrity design criteria.
6 citations
01 Feb 1987
TL;DR: In this paper, a comprehensive report providing an overview of geotechnical engineering aspects for coastal engineers to use in planning and design of coastal projects is presented, emphasizing the bearing capacity and settlement analysis, and retaining structures used to protect natural slopes.
Abstract: : This is comprehensive report providing an overview of geotechnical engineering aspects for coastal engineers to use in planning and design of coastal projects. The fundamentals of geotechnical engineering, including coastal area soil classification and engineering properties of soil analyses, are discussed first. Then, important geotechnical considerations in coastal site selection, methodologies of subsurface exploration and soil testing techniques, in the field and laboratory, are discussed in the initial chapters. The second half of this report focuses on specific types of coastal structures and the geotechnical aspects of each. Shallow foundations for gravity structures, emphasizing the bearing capacity and settlement analysis, and retaining structures, very common in the coastal area, are discussed. Particular emphasis is given to wave effects on bulkheads structures used to protect natural slopes. The final two chapters deal with slope stability relative to embankments or other man-made slopes such as breakwaters, jetties, and bulkenads as well as natural slopes. The contribution of slope instability to bluff erosion and geotechnical design procedures for planning correctives structures are also discussed. Keywords: Coastal engineering; Coasts; Geotechnical engineering.
6 citations
01 Jan 1987
TL;DR: In this paper, a system of beaches and offshore breakwaters was designed to protect eroding bluffs along the shoreline of the City of Lake Forest from eroding cliff faces.
Abstract: A system of beaches and offshore breakwaters was designed to protect eroding bluffs along the shoreline of the City of Lake Forest. The beach system consists of sand fill contained by a series of offshore breakwaters with shore-connected structures at either end. Individual beach units are separated by groins which extend shoreward from the offshore breakwaters. A three dimensional hydraulic model study was completed at a geometric scale of 1:20 to design the beach system. The effects of incident wave direction and water level on beach response and stability were assessed. Stable beach plans and profiles were developed under the model storm conditions. Construction of the offshore breakwaters began in the spring of 1986, with sand fill being placed in the fall of 1986.
01 Mar 1987
TL;DR: In this paper, a numerical study of the wave response of the proposed small boat harbor to be located on the west coast of Guam, near Agat, is described, where the HARBS finite element wave model is used to determine the wave responses of the base plan (Plan 1) and the following four alternative plans.
Abstract: : A numerical study of the wave response of the proposed small-boat harbor to be located on the west coast of Guam, near Agat, is described. The base plan considered consists of a basin dredged in the coral reef at the site, connected at its south end to the ocean by a 900-ft channel. Protective structures include revetments along the shore, a 190-ft stub breakwater and revetment at the south end of the harbor, and an 885-ft detached breakwater seaward of the harbor basin. The HARBS finite element wave model is used to determine the wave response of the base plan (Plan 1) and the following four alternative plans. The study found that Plan 4 (extended breakwater) best meets the requirements of the project. It is determined that this plan will keep the wave height in most of the harbor interior at 1 ft or lower 90 percent of the time. Plan 4 also gives the best wave protection for high water levels (as in storm surges). The plan provides the best overall wave protection for the smallest increase in construction cost over Plan 1.
01 Jan 1987
TL;DR: In this article, a short-crested wave system is used for bed scour, which can result in subsidence of caissons or rubble-rock placed in front for protection.
Abstract: Waves arriving obliquely to breakwaters establish a short-crested wave system which is very conducive to bed scour. This has been exhibited in models and also in prototype situations in Japan. The resulting troughs formed close to structures can result in subsidence of caissons or rubble-rock placed in front for protection.
TL;DR: The mathematical equations which relate the overturning and sliding safety factors of a breakwater and the allowable normal stress of the breakwater foundation to the dimensional ratio of the structure which is under the action of waves, as well as the minimum required breakwater widths to the other variables are determined as discussed by the authors.
01 Sep 1987
TL;DR: In this paper, the authors provide design guidance for sizing toe berm armor on breakwater and jetty trunks exposed to depth limited breaking waves whose crests approach at or near parallel to the structure.
Abstract: This memorandum provides design guidance for sizing toe berm armor on breakwater and jetty trunks exposed to depth limited breaking waves whose crests approach at or near parallel to the structure
01 Mar 1987
TL;DR: In this paper, a 1:52-scale 3D hydraulic model was used to investigate the design of a boat launching facility at Laupahoehoe Point, Hawaii, with respect to wave action.
Abstract: Abstract : A 1:52-scale three-dimensional (3-D) hydraulic model was used to investigate the design of a proposed boat-launching facility at Laupahoehoe Point, Hawaii, with respect to wave action. The model reproduced Laupahoehoe Point, approximately 3,000 ft of the Hawaiian shoreline, and sufficient offshore area in the Pacific Ocean to permit generation of the required test waves. Improvement plans included a rubble-mound breakwater armored with dolosse and stone, a wave absorber, a natural entrance channel, a turning basin, and a boat-launching ramp. A 20-ft-long electrohydraulic wave generator and an automated data acquisition and control system were utilized in model operation. Test results for the 3-D wave action model indicated that for base test conditions, rough and turbulent wave conditions existed in the vicinity of the proposed boat-launching facility not only during periods of severe wave attack but also for conditions when incident waves were 4- to 6-feet. Keywords: Navigation, Hawaii, Laupahoehoe Point, Safety measures, Models, Launches, Protection.
Journal Article•
TL;DR: A new rubble-mound breakwater design is proposed in this article, which is based on the properties and availabilities of local stone, instead of relying on Hudson's formula for the armor layer design.
Abstract: A new rubble-mound breakwater design is a departure from the conventional approach detailed in the U.S. Army Corps of Engineers Shore Protection Manual. The new concept, called the berm breakwater, is based on the properties and availabilities of local stone. Instead of relying on Hudson’s formula for the armor layer design, with the berm approach, armor layer thickness is determined by the available stone size. If smaller stones are used, the layer is thicker. In addition, a natural nesting and consolidation process takes place as the breakwater is exposed to wave action. The method saves money by incorporating indigenous material and construction is much easier because stones may simply be dumped at the site. Precise placement underwater is not necessary. Several successful case histories are described. In all cases, the method costs less than a conventional breakwater, or was built where a conventional breakwater would have required armor units weighing 40 tons or more, creating insurmountable logistic and economic obstacles. One failure is also described. Current international research on the technique is also covered.
01 Jan 1987
TL;DR: In this article, a discrete spectrum model developed by Dr. T. D. Resio was used to estimate waves from recorded hurricanes and was followed by extensive mathematical and physical model tests.
Abstract: The breakwaters protecting Port of Haina in the Dominican Republic have been repeatedly damaged by hurricane storm waves. Attempt to repair the destroyed portions have been largely unsuccessful. A discrete spectrum model developed by Dr. D. T. Resio was used to estimate waves from recorded hurricanes and was followed by extensive mathematical and physical model tests. The preferred solution involves reorientation of the breakwater head, placement of 80 and 26 metric ton concrete cubes on the head and exposed sections, and rehabilitation of the breakwaters by reuse of displaced five-, ten-, and fifteen-ton concrete blocks.
01 Jan 1987
TL;DR: In this article, the authors provide design guidance for sizing toe berm armor stone on breakwater and jetty trunks exposed to depth limited breaking waves whose crests approach at or near parallel to the structure.
Abstract: This technical note is to provide design guidance for sizing toe berm armor stone on breakwater and jetty trunks exposed to depth limited breaking waves whose crests approach at or near parallel to the structure.
TL;DR: In this paper, a pneumatic breakwater has been adopted to protect the racing field from the wind waves because it has an advantage of no interruption of common boat navigations through the river channel.
Abstract: At the Edogawa moterboat racing stadium located at a tidal river channel in Tokyo, moterboat races have sometimes become difficult to open by wind waves during spring gales. A pneumatic breakwater has been planned to be adopted to protect the racing field from the wind waves because it has an advantage of no interruption of common boat navigations through the river channel. However, the breakwater performance of wave damping in the water field where the tidal current exists in addition to the river current is not clear yet.The present study shows the results of the field test and discusses the applicability of the pneumatic breakwater to tidal rivers. It is found from the data analysis that the pneumatic breakwater in the field with the tidal current maintains almost same performance of wave damping as that without the current.