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Model testing of rubble mound breakwater toe units on steep rocky sea beds
Thesis (MEng)--Stellenbosch University, 2024.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2024
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| _version_ | 1867613851428585472 |
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| access_status_str | Open Access |
| author | Brits, Jeandre Adriaan |
| author2 | Theron, Andre Karl |
| author_browse | Brits, Jeandre Adriaan Theron, Andre Karl |
| author_facet | Theron, Andre Karl Brits, Jeandre Adriaan |
| author_sort | Brits, Jeandre Adriaan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/130578 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:42:41.823Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/130578 Model testing of rubble mound breakwater toe units on steep rocky sea beds Brits, Jeandre Adriaan Theron, Andre Karl Wehlitz, Carl-Peter Friedrich von Moltke Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Rubble mound breakwaters Piling (Civil engineering) Construction projects Dolomite Engineering models Thesis (MEng)--Stellenbosch University, 2024. ENGLISH ABSTRACT: This thesis documents the design and two-dimensional physical model testing at a scale of 1:32, of a new rubble mound breakwater toe structure concept. The purpose of the new concept is to provide a more efficient and economical solution to construct rubble mound breakwater type structures on steep rocky coastlines. Literature from past studies and construction projects of rubble mound structures on rocky coasts was studied. The concepts from these tests and projects inspired the newly developed concept design. The literature study concluded that piles was the best current solution for the toe structures on steep rocky coasts. The new concept implements the use of piles, but in a more efficient manner. Piles are drilled into the seabed at set intervals to provide anchorage to the toe structure. The functioning of the toe units enables the interval between the piles to be significantly longer, than with other methods of using piles for breakwater toes. A longer interval reduces the number of piles required to be installed in a project, which may lead to cost savings, as piling is very expensive. The practical implementation would be to drill the piles into the seabed and slide specially designed anchor units over the piles. The toe units tested in this study would then be placed to fill the space between the anchor units. The proposed toe design developed consists of chevron shaped concrete units packed in an arch shape between 2 specially designed concrete units, fixed to the rocky seabed with piles. A 1 in 7 gradient concrete slope was constructed at the rear of the flume on which the breakwater was tested. The flume in this part was divided into three, 1.33 m wide sections so that breakwaters with Cube, Dolos and rock armour could be tested simultaneously. The breakwater armour was constructed at a slope of 1:1.5. The different types of armour gave insight into how the properties and behaviour of the armour layer influences the toe structure. The aim of the tests was to determine if the concept is feasible to be developed further or not. The test results indicated that the toe system has potential to become an efficient solution to construct rubble mound breakwaters on steep rocky coasts. The toe system in the model tests provided sufficient support to the cube and rock breakwaters up to wave heights that damaged the armour layers substantially. The rock armoured breakwater provided the most support to the toe structure and therefore performed the best during the testing. The cube armour layer failed before its toe became unstable. The toe started failing shortly after the cube armour layer began sustaining significant damage. The Dolos armour was very stable due to its high interlocking properties. The toe failed before damage to the Dolos layer was noted. The toe structure at the Dolos breakwater failed in the test after the Cube breakwater failed. The rock breakwater toe remained stable significantly longer. The influence of the downward force exerted by the armour layer onto the toe structure is therefore deemed critical in the design of breakwaters with this toe structure. The downward force is essential in preventing the upward buckling of the toe, which is the main failure mechanism of the designed toe structure. The physical model tests done in this study provided insight into the behaviour of the toe structure under the selected wave loads. Guidelines to improve the design are given, based on the test observations. Guidelines determined during this study are that the contact surface between the units are an important design factor (Area of V-part), similar to how the stability of Seabee units only depend on contact surface area. The packing design in an arch shape is also of outmost importance. The future development and further model testing of the toe concept are recommended based on the test results obtained. Design and test setup improvements should be implemented to confirm the feasibility of the breakwater toe concept. AFRIKAANSE OPSOMMING: Hierdie tesis doen verslag oor die ontwerp en twee-dimensionele fiesiese model toetse teen skaal 1:32, van ‘n nuwe toon struktuur konsep, vir ruklip breekwaters. Die doel van die nuwe konsep is om ‘n meer effektiewe en ekonomiese oplossing te ontwikkel om puinwal breekwaters op steil rots-kuslyne te kan bou. Literatuur van studies en konstruksie projekte wat oor ruklip breekwaters op rotskuslyne handel, was gebruik om die toon struktuur konsep sowel as die model toetse te ontwerp. Die literatuur studie het tot die gevolgtrekking gekom dat die gebruik van heipale huidiglik die beste opsie is vir ‘n breekwater toon op steil rotskuslyne. Die nuwe toon konsep maak gebruik van heipale, maar in ‘n baie meer effektiewe wyse. Die funksie van die toon eenhede is om ‘n aansienlik groter spasiëring van die heipale te gebriuk, in vergelyking met die huidige toonkonstruksie metodes. Dit beteken dat minder heipale benodig word vir ‘n breakwater projek en kan lei tot kostebesparings aangesien heipale baie duur is. Die praktiese toepasing sal behels dat die nodige heipale in die seebodem ingeboor word en spesiaal ontwerpte anker eenhede oor die heipale geplaas word. Die tooneenhede wat in die studie getoets was word dan gebruik om die spasie tussen die heipale te oorbrug. Die voorgestelde toon ontwerp wat in die studie ontwikkel is, bestaan uit chevron patroon beton eenhede wat in ‘n boog vorm gepak word, tussen 2 spesiaal ontwerpte beton eenhede wat met heipale aan die rots seebodem geanker is. ‘n 1 in 7 gradient beton vloer was aan die vêr kant van die kanaal gebou, waarop die breekwaters getoets was. Die kanaal by die vloer was in 3 dele van 1.33 m breed gedeel, sodat breekwaters met kubus, Dolos en rots bewapening gelyktydig getoets kon word. Die breekwaters was met ‘n helling van 1:1.5 gebou. Die verskillende bewapenings eenhede wat getoets was, het insig verskaf aan hoe die eienskappe en reaksie van die bewapeningslaag die toon struktuur beinvloed. Die doel van die model toetse was om te bepaal of die toonkonsep die potensiaal het om verder ontwikkel te word as ‘n lewensvatbare oplossing om puinwal strukture op steil rotskuslyne te bou. Die toetsresultate toon aan dat die kosep potensiaal het om ‘n effektiewe oplossing te word. Die toonstruktuur in die modeltoetse het stabiel gebly en die nodige ondersteuning aan die kubus en rots breekwaters gebied, tot op golfhoogtes waar die bewapeningslaag alreeds aansienlike skade getoon het. Die rots bewapende breekwater het die meeste potentiaal saam met die toon struktuur getoon en die beste resultate gewys. Die kubus bewapening het gefaal voor die toonstrutuur onder dit onstabiliteit getoon het. Die toon het onstabiel begin raak kort nadat aansienlike skade aan die kubus bewapeningslaag plaas gevind het. Die Dolos bewapeningslaag was baie stabiel weens die goeie ineensluitende eienskappe van die eenhede. Die toonstruktuur by die Dolos breekwater het gefaal in die toets nadat die kubus breekwater gefaal het. Die toon het gefaal voordat skade aan die Doloslaag sigbaar was. Die rots breekwater het relatief stabiel gebly vir baie langer as die ander breekwaters. Die invloed van die druk wat die bewapeningslaag op die toon uitoefen was gevind om ‘n kritiese ontwerpskriteria te wees vir die stabiliteit van die toonstruktuur konsep wat getoets was. Die afwaardse druk wat die bewapeningseenhede Op die toonstruktuur uitoefen is nodig om die moontlikheid van opwaardse swigting van die toonstruktuur te verminder. Die opwaartse swigting is givind om die hoof faalmeganisme van die toonstruktuur konsep te wees. Die fisiese modeltoetse wat in die studie gedoen is het waardevolle inligting verskaf oor die reaksie van die toonstruktuur onder golfladings. Riglyne vir die verbetering van die ontwerp, gebaseer op die modeltoetse word gegee. Die riglyne wat deur die studie opgemerk is behels dat die plasingsontwerp van die toonstruktuur van uiterse belang is. Die ander belangrike ontwerpsaspek is die kontakoppervlak tussen die eenhede (Area van V-deel), soortgelyk aan hoe die stabiliteit van Seebee eenhede slegs van hul kontakoppervlakte afhanklik is. Die toekomstige ontwikkeling en verdere model toetse van die voorgestelde konsep word aanbeveel, gebaseer op die resultate van die toetse hierin bespreek. Die voorgestelde ontwerp, en toets verbeteringe moet geïmplementeer word om dan die uiteindelike lewensvatbaarheid van die toonstruktuur te bevestig. Masters 2024-01-18T12:23:01Z 2024-04-26T22:42:47Z 2024-01-18T12:23:01Z 2024-04-26T22:42:47Z 2024-01 Thesis https://scholar.sun.ac.za/handle/10019.1/130578 en_ZA en_ZA Stellenbosch University xvii, 146 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Rubble mound breakwaters Piling (Civil engineering) Construction projects Dolomite Engineering models Brits, Jeandre Adriaan Model testing of rubble mound breakwater toe units on steep rocky sea beds |
| title | Model testing of rubble mound breakwater toe units on steep rocky sea beds |
| title_full | Model testing of rubble mound breakwater toe units on steep rocky sea beds |
| title_fullStr | Model testing of rubble mound breakwater toe units on steep rocky sea beds |
| title_full_unstemmed | Model testing of rubble mound breakwater toe units on steep rocky sea beds |
| title_short | Model testing of rubble mound breakwater toe units on steep rocky sea beds |
| title_sort | model testing of rubble mound breakwater toe units on steep rocky sea beds |
| topic | Rubble mound breakwaters Piling (Civil engineering) Construction projects Dolomite Engineering models |
| url | https://scholar.sun.ac.za/handle/10019.1/130578 |
| work_keys_str_mv | AT britsjeandreadriaan modeltestingofrubblemoundbreakwatertoeunitsonsteeprockyseabeds |