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Domestic water demand for consumers with rainwater harvesting systemsO Brien, Olivia 04 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The focus of the study is to theoretically assess tank-water demand and employ methods to establish the actual tank-water demand at selected houses in a case study area. This study also examines the influence of domestic rainwater harvesting systems when used in combination with a municipal water distribution system. The case study comprises of 410 low cost housing units in the Western Cape. The system demand patterns of low cost housing units are uncharacteristic, when compared with suburban system demand patterns, and cannot be defined by traditional models. Similarly, the use of rainwater harvesting systems in these areas follows an unconventional routine that is yet to be defined.
A stochastic end-use model for water demand is developed which produces temporal profiles for water supplied from both sources, namely the water distribution system and the rainwater harvesting system. The model approximates a daily system and tank-water demand pattern for a single domestic household, using @RISK software. The demand estimation methodology is clarified through application on a particular case study site where harvested rainwater is frequently utilized. Estimates of the parameter values are based on consumer surveys and previous studies on the case study area, where the household size was defined in the form of a probability distribution. The results confirm the atypical system demand patterns in low cost housing units units. Although two clear peaks exist in the morning and in the evening, a relatively constant average flow is present throughout the day. A sensitivity analysis of all the model parameters verified that the household size has the most substantial influence on the tank-water demand pattern. The system and tank-water demand patterns were compared to published average daily water demand guidelines, which confirmed that increased water savings could be achieved when the rainwater source is accessible inside the household with minimal effort.
The stochastic demand profiles derived as part of this research agree with the metered system demand in the same area. The results of this study could be incorporated into the future development of national standards. / AFRIKAANSE OPSOMMING: Die fokus van die studie is om die tenkwater-aanvraag teoreties te ontleed en metodes in werking te stel om die werklike tenkwater-aanvraag vas te stel by geselekteerde huise in ‘n gevallestudie area. Hierdie studie ondersoek ook die invloed van plaaslike reënwater-herwinningstelsels wanneer dit gebruik word in kombinasie met ‘n munisipale waterverspreidingstelsel. Die gevallestudie bestaan uit 410 laekoste behuisingseenhede in die Wes-Kaap. Die stelsel-aanvraagpatrone van laekoste behuisingseenhede is verskillend wanneer dit met voorstedelike stelsel-aanvraagpatrone vergelyk word en kan nie gedefinieer word deur tradisionele modelle nie. Soortgelyk volg die gebruik van reënwater-herwinningstelsels in hierdie areas ‘n onkonvensionele roetine.
‘n Stogastiese eindgebruikmodel vir water-aanvraag is ontwikkel, wat tydelike profiele genereer vir water wat van beide bronne verskaf word, naamlik die waterverspreidingstelsel en die reënwater-herwinningstelsel. Die model bepaal by benadering ‘n daaglikse stelsel- en tenkwater-aanvraagpatroon vir ‘n enkele plaaslike huishouding, deur @RISK sagteware. Die aanvraag-beramingstegnieke word verduidelik deur toepassing op ‘n spesifieke gevallestudie, waar herwinde reënwater gereeld gebruik word. Die parameter waardeberamings is gebaseer op verbruikers-opnames en vorige studies oor die gevallestudie-gebied, waar die grootte van die huishoudings bepaal was in die vorm van 'n waarskynlikheidsverspreiding. Die resultate bevestig die atipiese stesel aanvraagpatrone in laekoste behuisingseenhede eenhede. Alhoewel twee duidelike pieke in die oggend en die aand voorkom, is ‘n relatiewe konstante vloei dwarsdeur die dag teenwoordig. ‘n Sensitiwiteitsanalise van al die modelparameters bevestig dat die grootte van die huishouding die grootste beduidende invloed op tenkwater- aanvraagpatrone het. Die stelsel- en tenkwater-aanvraagpatrone was vergelyk met gepubliseerde gemiddelde daaglikse water-aanvraag riglyne wat bevestig dat meer waterbesparings bereik kan word waar die reënwaterbron binne die huishouding beskikbaar is met minimale moeite.
Die stogastiese aanvraagprofiele, wat as deel van hierdie navorsing afgelei was, stem saam met die gemeterde stelsel-aanvraagpatroon van dieselfde area. Die resultate van hierdie studie kan in die toekomstige ontwikkeling van nasionale standaarde opgeneem word.
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Development of a multi-criteria assessment tool to choose between housing systems for the low cost housing marketTheart, Petrus Johannes 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: It is well known that South Africa has a major housing backlog and that the population is
growing every year. Consequently, more people are left homeless, without the finances to
acquire a minimum standard house. The official backlog in 2012 was defined as 2.1 million
units, of which 1.1 million households lived in informal settlements in South Africa.
The purpose of this study is to develop a multi-criteria assessment tool that will help a
developer to choose between housing systems that can be used in low cost housing
developments. Essentially, the tool will aid a developer to allocate funding more appropriately
and effectively to develop sustainable communities.
The research followed a procedure of identifying challenges experienced in the low cost
housing industry, identifying the important factors to consider when assessing low cost
housing systems and finally selecting a multi-criteria decision-making model to select a
system. The important factors that need to be considered for this study were gathered from
literature and industry experience through using the interviewing technique for data
collection. The factors identified will be assessed using the multi-criteria decision-making
model, called the Evidential Reasoning Approach.
This study focuses on housing systems as a whole. Specific attention is given to walling
systems, but not to other elements such as the foundations and roofs. The primary factors
identified are cost, time, quality, environmental performance, density, alteration capability,
resource availability and additional features. These factors were then used to develop a userfriendly
assessment tool for choosing between housing systems for the low cost housing
market. In conclusion this assessment tool will be available to public and private role players who
intend to develop a low cost housing settlement. However, this assessment tool has some
imperfections. These are discussed at the end of this study and show how they influence this
model. / AFRIKAANSE OPSOMMING: Dit is algemeen bekend dat Suid-Afrika „n groot behuisings agterstand het en dat die
bevolking jaarlikse groei. Die amptelike behuisings agterstand in 2012 was gedefinieer as 2.1
miljoen eenhede, waarvan meer as 1.1 miljoen van hierdie huishoudings in informele
nedersettings in Suid-Afrika geleë is.
Die doel van hierdie studie is dus om „n mulit-kriteria assesserings instrument te ontwikkel
wat „n ontwikkelaar sal help om tussen behuisings sisteme te kies, wat vir lae koste behuising
ontwikkelings gebruik kan word. Gevolglik , sal hierdie instrument „n ontwikkelaar help om
befondsing meer toepaslik toe te ken en om doeltreffende en volhoubare gemeenskappe te
ontwikkel.
Die navorsings prosedure het begin deur uidagings in die lae koste behuising bedryf te
identifiseer, asook die belangrike faktore wat oorweeg moet word as behuisings stelsels
beoordeel moet word. „n Multi-kriteria besluitnemings model is gekies wat toepaslik is op
hierdie studie. Die belangrike faktore wat in ag geneem moet word, is geïdentifiseer deur
literatuur, en industrie ondervinding, deur gebruik te maak van onderhoude om data in te
samel. Die kriteria wat geïdentifiseer is sal beoordeel word met behulp van die multi-kriteria
besluitnemings model, naamlik Evidential Reasoning Approach.
Die kriteria wat gebuik is in hierdie studie het gefokus op die behuisings stelsel as ʼn geheel.
Alhoewel spesifieke aandag gegee is aan die mure van die stelsels was ander elemente, soos
die dakke en fondamente nie bespreek nie. Die primêre faktore wat geïdentifiseer is, is koste,
tyd, kwaliteit, omgewings werkverrigting, digtheid, aanbouings vermoë, beskikbaarheid van
hulpbronne en bykomende funksies. Hierdie faktore word gebruik om „n keuse te maak tussen
behuisings stelsels vir die gebruik vin die lae koste behuising mark. Die faktore word
voorgestel as „n gebruikers vriendelike assesserings instrument. Ten slotte behoort hierdie assesserings intrument beskikbaar te wees aan oopenbare en private
belangstellendes wat beoog om „n lae kost behuising nedersetting te ontwikkel. Hierdie
assesserings instrument het wel „n paar tekortkomming, wat aan die enide van die studie
bespreek word, asook hoe hierdie terkortkomming die model kan beïnvloed.
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An investigation into the time and cost factors for a decision between in-situ and hybrid concrete constructionPiek, Philippus Jacobus 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The construction industry is a competitive market and contractors need to keep up-to-date with new
construction methods and technologies. Project teams in South Africa are required to make decisions
during the early stages of construction projects. These decisions often need to be made in a short time
period, and include the decision between various construction methods, such as the decision between
in-situ concrete construction and hybrid concrete construction.
Hybrid concrete construction is a combination of pre-fabricated concrete and cast in-situ concrete to
obtain the supreme benefits of their different construction qualities. This method of construction is
ultimately used to achieve faster, and occasionally, more cost effective construction. Hybrid concrete
construction, today, is a well-known term in the construction industry and is widely used in the UK
and other developed countries. However, the use thereof is limited in South Africa, and in-situ
concrete construction remains the conventional method of construction. Possible reasons for the
limited use of hybrid concrete construction are investigated in this study. With the intent of improving
the construction industry of South Africa, guidelines are provided to assist project teams in a decision
between in-situ concrete construction and hybrid concrete construction.
The decision between construction methods is based on many factors, such as project time, cost,
quality, safety, environmental performance, socio-economic aspects (labour) and client satisfaction.
Project time and cost are, however, the most important of these factors. It is stated that the structure of
a building represents typically only 10 % of the construction cost, however, the choice of construction
method and material can have significant effects on the cost of other elements throughout the life cycle
of construction projects. It is therefore important to measure the whole life cycle cost when deciding
between construction methods, such as in-situ concrete construction and hybrid concrete construction.
The aim of this study is to identify and investigate the factors that influence project time and cost,
throughout the life cycle of construction projects, and to provide a framework that can assist project
teams in their decision between in-situ concrete construction and hybrid concrete construction in
South Africa. The decision between these two construction methods is influenced by a vast number of
variables that may be difficult to quantify. The framework therefore consists of qualitative information
that can assist project teams in their decision.
The framework provided in this study includes the factors that have an influence on the time and cost
for a decision between in-situ concrete construction and hybrid concrete construction. These factors
are identified for the three primary phases in the life cycle of construction projects. These phases are
the design phase, the construction phase and the maintenance phase. / AFRIKAANSE OPSOMMING: Die konstruksiebedryf is 'n kompiterende mark en kontrakteurs moet op datum bly met nuwe
konstruksie metodes en tegnologieë. In Suid-Afrika word daar van projek spanne vereis om vinnige
besluite gedurende vroeë stadiums van 'n projek te neem. Hierdie besluite moet dikwels in 'n kort
tydperk geneem word, en sluit die besluit tussen verskillende konstruksie metodes in, byvoorbeeld die
besluit tussen in-situ en hibriede beton konstruksie.
Hibriede beton konstruksie (HBK) is 'n kombinasie van in-situ en voorafvervaardigde beton elemente.
HBK word in die algemeen gebruik om te baat uit 'n vinniger konstruksie tydperk, en kan soms ook ‘n
meer koste-effektiewe metode van konstruksie wees. HBK word gesien as 'n bekende term in die
konstruksiebedryf en word veral toegepas in ontwikkelde lande soos die VSA, Japan en Engeland. Die
toepassing daarvan in Suid-Afrika is egter beperk. In Suid-Afrika word in-situ beton konstruksie nog
steeds die meeste gebruik en staan dus bekend as die mees algemene metode van konstruksie. Hierdie
studie ondersoek moontlike redes vir die beperkte gebruik van HBK in Suid-Afrika. Met die oog op 'n
verbeterde konstruksiebedryf in Suid-Afrika, word rigylyne voorsien, wat projek spanne kan gebruik
vir 'n besluit tussen in-situ en hibriede beton konstruksie.
Daar is verskeie faktore wat 'n rol speel in die besluit tussen twee konstruksie metodes. Hierdie faktore
sluit in, die tyd, koste, kwaliteit, veilighed, omgewings impak, sosio-ekonomiese aspekte (soos arbeid)
en kliënt tevredenheid, van 'n projek. Tyd en koste is egter die belangrikste van hierdie faktore. Die
metode waarvolgens 'n struktuur gebou word kan 'n beduidende uitwerking op die koste van ander
elemente in die lewensiklus van 'n konstruksie projek hê. Dit is gevolglik belangrik om die hele
lewensiklus koste in ag te neem wanneer daar besluit moet word tussen verskeie konstruksie metodes,
soos in-situ en hibriede beton konstruksie.
Die doel van hierdie studie is gevolglik om die faktore wat 'n invloed het op die tyd en lewensiklus
koste van konstruksie projekte te identifiesieer. Hierdie faktore word dan gebruik om 'n raamwerk
voor te stel. Projek spanne kan hierdie raamwerk gebruik as 'n riglyn om te besluit tussen in-situ en
hibriede beton konstruksie. Die besluit tussen hierdie twee konstruksie metodes is afhanklik van 'n
groot aantal veranderlikes, wat moeilik is om te kwantifiseer. Die raamwerk bestaan dus uit
kwalitatiewe inligting wat projek spanne kan gebruik om 'n ingeligte besluit te neem oor in-situ en
hibriede beton konstruksie.
Die raamwerk wat in hierdie studie voorgestel word sluit dus die faktore in wat 'n invloed het op die
tyd en koste vir 'n besluit tussen in-situ en hibriede beton konstruksie. Hierdie faktore is geïdentifiseer
vir die drie primêre fases in die lewensiklus van 'n konstruksie projek. Hierdie fases is die ontwerp
fase, die konstruksie fase en die onderhoud fase.
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Evaluation of adhesion properties in bitumen-aggregate systems for winter surfacing seals using the bitumen bond strength testTwagirimana, Emmanuel 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Flexible pavement designers have a choice of two wearing course: either asphalt concrete or surfacing seals. The latter have been widely used by several countries as their preferred wearing course over other methods, especially countries with a limited number of average inhabitants per square kilometre. Moreover, the surfacing seals were identified as an efficient cost effective road preventive maintenance technique. Surfacing seals in New Zealand, South Africa and Australia cover about 65%, 80% and 90% of their surfaced road networks respectively. The preference of surfacing seals is due to their competitive initial cost and ease of construction.
In South Africa, the life expectancy of surfacing seals varies between 8 and 12 years with an average of 10 years. This has not been the case in a number of surfacing seals constructed in winter, especially when the night recorded temperature is below 10oC. The dominant failure mechanism is ravelling (chip loss) soon after construction due to traffic loading. This chip loss is linked to the poor adhesion bond development rate in the bitumen-aggregate system during winter adverse conditions. In order to address the issue of premature chip loss the need for the development of a robust adhesion test method was identified. For that purpose, recently, researchers in the bitumen industry developed the Bitumen Bond Strength test method. This method was used in this study.
This study intends to contribute to the understanding of binder-aggregate adhesion bond development for winter surfacing seals using the BBS test. Binder type, precoat type and conditioning, aggregate type and curing time are amongst the factors influencing winter seals adhesion bond performance. An experimental matrix involving three types of binder, two types of aggregate, four different precoating fluids, two precoat conditionings and two binder-curing times were then developed and investigated. Winter weather parameters affecting adhesion properties were also taken into consideration during the course of the investigation. Throughout the test, the procedure described in AASHTO TP 91-11 was followed. However, in order to enhance the control of the binder application temperature, a new method for hot applied binder sample preparation was developed as part of this study. The findings show that there is a significant difference between adhesion properties of the hot applied binders (70/100 and S-E1) and the emulsion (SC-E1). In most of the cases, the hot applied binders performed better than the emulsion. The failure mode observed was found to be linked to the condition of the precoating. The influence of the precoat type and conditioning, and effect of binder curing time were significantly highlighted. The use of a dry precoat benefited the adhesion bond strength up to around 50% relatively to the corresponding non-precoated combination. However, a decrement in the bond strength due to precoating of up to 28.7% was also observed.
A statistical analysis using ANOVA did not illustrate any statistical significant effect of the aggregate type. The interaction effects analysis using ANOVA revealed the aggregate type interacting with precoat type to be the most influential interaction at level two. The precoat conditioning implication to the adhesion development rate, which influences the time for opening to traffic after construction, was illustrated. Insightful aspects on the compatibility between the binder type and precoat type and conditioning during the aggregate precoating practices and on the time for opening to traffic are highlighted. Finally, the repeatability analysis proved the BBS test to be a repeatable testing method with caution. Recommendations for further studies that could support the conclusions drawn in this study were provided. / AFRIKAANSE OPSOMMING: Buigbare plaveiselontwerpers het 'n keuse van twee deklae: óf Asfalt of oppervlak seëls. Laasgenoemde word algemeen gebruik deur verskeie lande as hul voorkeur deklaag, veral die lande met beperkte aantal gemiddelde inwoners per vierkante kilometer. Verder, is die seëls geïdentifiseer as 'n doeltreffende koste-effektiewe deklaag tegniek. Oppervlakseëls in Nieu-Seeland, Suid-Afrika en Australië dek ongeveer 65%, 80% en 90% van hul padnetwerke onderskeidelik. Die seëls se voorkeur is te danke aan hul mededingende aanvanklike koste en eenvoudige vorm van die konstruksie.
In Suid-Afrika wissel die seël se lewensverwagting tussen 8 en 12 jaar met 'n gemiddeld van 10 jaar. Dit is egter nie die geval van 'n aantal seëls wat in die winter gebou word nie, veral wanneer die aangetekende nagtemperatuur onder 10o C daal nie. Die dominante swigtingsmeganisme is stroping (klipverlies) kort na konstruksie. Hierdie klipverlies is gekoppel aan die power kleef-ontwikkeling van bitumen gedurende die winter. Ten einde die probleem van voortydige klipverlies aan te spreek het die behoefte vir die ontwikkeling van 'n robuuste toetsmetode ontstaan. Om hierdie rede het navorsers onlangs in die bitumenbedryf die “BBS toetsmetode” ontwikkel en is dié toetsmetode in hierdie studie gebruik.
Hierdie studie beoog om by te dra tot die begrip van bindmiddel-klip kleefontwikkeling vir die winter seëls dmv die BBS toets. Die faktore, insluitend maar nie beperk tot bindmiddeltipe, voorafdekking (“PRECOAT”) -tipe en kondisionering, aggregaattipe en kuurtyd beïnvloed winter seëls se kleefeienskappe. 'n Eksperimentele matriks met drie tipes bindmiddels, twee tipes aggregate, vier verskillende voorafdekking-vloeistowwe, twee voorafdekking kondisionering en twee bindmiddel kuurtye is toe ontwikkel en ondersoek. Winter weer parameters wat kleefeienskappe beïnvloed is ook in ag geneem tydens die verloop van die ondersoek. Regdeur die studie is die prosedure AASHTO TP 91-11 gevolg, maar ten einde die beheer van die bindmiddel spuittemperatuur te verbeter, is ‘n nuwe metode vir warmspuit-bindmonsters voorbereiding ontwikkel as deel van hierdie studie. Die bevindinge toon dat daar 'n beduidende verskil tussen die kleefeienskappe van die warm aangewende bindmiddels (70/100 en S-E1) en die emulsie (SC-E1) is. In die meeste van die gevalle het die warmspuit-bindmiddels beter as emulsie gevaar. Daar is gevind dat die swigtingsmeganisme verbind word met die toestand van die voorafdekking. Die invloed van voorafdekkingtipe, kondisionering, en die effek van bindmiddelkuurtyd is duidelik uitgelig. Die gebruik van droë voorafdekking het die kleefkrag tot sowat 50% verhoog relatief tot die ooreenstemmende onbedekte klipkombinasie. Daar is egter ook ‘n verlaging van die kleefkrag weens voorafdekking gevind van tot so hoog soos 28,7 persent.
Die statistiese ontleding met behulp van ANOVA het geen statisties beduidende effek van die verksillende aggregaattipe te vore gebring nie. Die interaksie-effek analise, met behulp van ANOVA, het wel die interaksie met voorafdekkingtipe met aggregaat die mees invloedryke bevestig. Die voorafdekking kondisioneering het ver rykende kleefkrag implikasies bloot gelê, wat die tyd vir die opening van die verkeer na konstruksie beïnvloed. Insigwekkende aspekte oor die versoenbaarheid tussen die bindmiddeltipe, voorafdekkingtipe, kondisionering, voorafdekkingpraktyk en tyd tot opening vir verkeer word uitgelig. Ten slotte, die herhaalbaarheidsanalise het die BBS toets as 'n herhaalbare toetsmetode met omsigtigheid bewys. Daar is aanbevelings tot verdere studies, wat uit die gevolgtrekking gekom het, gemaak.
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A feasible design concept for the deep water breakwater of the proposed new Durban Dig-Out PortWust, Isak 12 1900 (has links)
Thesis (MEng)–Stellenbosch University, 2014. / ENGLISH ABSTRACT: The Port of Durban is forecasted to reach its capacity in terms of container handling soon,
which necessitates the investigation of an alternative port in the vicinity. The old Durban
Airport site has been identified as a potential location to develop a new deep water
container harbour. This is driven by a demand for deep water berth capacity as a result of
shipping liners preferring the benefits of scale in their operations, leading to the use of
larger ships with deeper drafts. To protect the new port from wave energy penetrating
inside the basin as well as from sedimentation from the adjacent beaches, the design and
construction of breakwaters are required.
The proposed main breakwater for this dig-out port is expected to extend 1 200m into
the sea, up to depths of 30m at the seaward roundhead. The deeper parts of the
breakwater face wave onslaught in a different manner than a conventional breakwater in
shallower waters. At these larger depths, the breakwater has to dissipate the energy of
non-breaking waves.
In this thesis, the wave climate nearshore, adjacent to the proposed breakwater is studied
and extreme wave events are simulated with a SWAN numerical model. The results for a
range of wave conditions, corresponding to selected events up to a return period of one in
100 years, are presented.
A study of deep water breakwaters was undertaken to investigate other examples of
similar structures. This indicated a clear distinction between vertical wall type
breakwaters and the more traditional rubble-mound type breakwaters. For this thesis, a
rubble-mound breakwater was chosen as the breakwater type for testing under
conditions of the Durban Dig-Out Port (DDOP). Focussing on a deep water trunk section
of the proposed main breakwater, a concept cross-section was designed using
deterministic design methods. The formulae incorporated in this method did however not
take into account the packing density of the armour layer and only assumed the
recommended values.
The hypothesis is thus put forward that the breakwater will still be hydraulically stable
for packing densities below the recommended values. This would decrease material
consumption and save on cost over the entire breakwater. A physical model was designed
to experiment with different armour layer configurations of single- and double layer
Cubipod arrangements. The unit was chosen for its massive shape and structural integrity
even during impact. A physical model study was performed at the facilities of the CSIR in Stellenbosch. It
entailed setting up a fixed-bed two-dimensional physical model in a glass wave flume.
Measuring wave heights, wave reflection, overtopping, wave transmission and armour
damage, the hydraulic stability and operational performance were analysed for several
tests. Based on the results of the first few test series, alterations were made to the
breakwater geometry and armouring.
The results confirmed the hypothesis that lower packing densities were still hydraulically
stable under 1 in 100 year return period wave conditions without inhibiting operational
performance. A final cross-section is presented as concept design for the deep section of
the proposed DDOP main breakwater. / AFRIKAANSE OPSOMMING: Volgens vooruitsigte gaan Durban hawe binnekort sy kapasiteit bereik wat die hantering
van skeepshouers betref. Hierdie verwikkeling noodsaak die ondersoek na ‘n
alternatiewe hawe in die nabye omgewing. Die voormalige Durban lughawe is intussen
geïdentifiseer as ‘n potensiële perseel waar ‘n diep water houervrag hawe ontwikkel kan
word. Dit word gedryf deur die aanvraag na diep water kaai kapasiteit as gevolg van skip
operateurs wat skaalvoordele verkies, sodat groter skepe met diep rompe meer populêr
word. Die ontwerp en konstruksie van breekwaters word dus benodig, om te verhoed dat
beide golwe, sowel as sediment van aangrensende strande, die hawe binnedring.
Die voorgestelde hoof breekwater vir hierdie hawe sal na verwagting tot 1200m in die
see in strek, waar dit tot 30m diep is naby die seewaartse hoof van dié breekwater. Die
dieper gedeeltes van só ‘n breekwater sal blootgestel word aan ‘n ander soort golf aanslag
as ‘n soortgelyke konvensionele breekwater in vlakker water. In hierdie waterdiepte is
die breekwater verantwoordelik vir die energie verbreking van ongebreekte golwe.
In hierdie tesis word die golfklimaat langs die kus, naby aan die voorgestelde breekwater
bestudeer. Die uiterste golf gebeurtenisse word gesimuleer met ‘n SWAN numeriese
model. Die resultate van ‘n reeks golf kondisies, ooreenstemmend met bepaalde
gebeurtenissemet herhaal periodes van tot 100 jaar, word aangebied.
‘n Studie van diep water breekwaters is onderneem om voorbeelde van soortgelyke
strukture te ondersoek. Die studie toon ‘n definitiewe onderskeid tussen vertikale muur
breekwaters en die meer tradisionele “rubble-mound” breekwater tipes. Vir hierdie tesis
is die “rubble-mound” breekwater tipe gekies vir toetsing, onderhewig aan die kondisies
van die “Durban Dig-Out Port” (DDOP). ‘n Konsep deursnit is ontwerp vir ‘n diep water
romp gedeelte van die voorgestelde hoof breekwater, deur van deterministiese metodes
gebruik te maak. Die formules soos vervat in hierdie proses maak egter nie voorsiening
vir die pakdigtheid van die bewapeningslaag nie, maar aanvaar slegs die voorgestelde
waardes.
Die hipotese word dus aangevoer dat die breekwater steeds hidrolies stabiel sal wees vir
pakdigthede wat laer as die voorgestelde waardes is. Dit sal die verbruik van materiale
verlaag en lei tot koste besparings vir die breekwater. ‘n Fisiese model is ontwerp om te
eksperimenteer met verskillende opstellings van die bewapeningslaag. Dit sluit enkel- en
dubbel laag bewapening met Cubipod eenhede in. Hierdie eenheid is gekies vir sy
massiewe vorm en strukturele integriteit, selfs tydens impak. ‘n Fisiese model studie is uitgevoer by die fasiliteite van die WNNR in Stellenbosch. Dit
het die opstel van ‘n vaste-bodem, twee-dimensionele fisiese model in ‘n glas golftenk
(“wave flume”) behels. Hidroliese stabiliteit en operasionele werksverrigting is
geanaliseer deur golf hoogtes, -weerkaatsing, -oorslag, -deurlating, en skade aan die
bewapening te meet vir verskeie toetse. Gebasseer op die resultate van die eerste paar
toetsreekse, is veranderinge gemaak aan die breekwater se geometrie en bewapening.
Die resultate het die hipotese bevestig dat laer pakdigthede steeds hidrolies stabiel is
tydens golf kondisies met ‘n 1 in 100 jaar herhaal periode, sonder om die werksverrigting
van die breekwater te belemmer. ‘n Finale deursnit word voorgestel as ‘n konsepontwerp
vir die diep water deursnit van die DDOP se hoof breekwater.
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A preliminary analysis of the sediment budget across the Swartvlei estuary mouthRoets, Adriaan 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The Swartvlei estuary and lake system is situated on the southern coast of the Western Cape
Province of South Africa and forms part of the core conservation area of the Wilderness
National Park. The Swartvlei system comprises two interlinked water bodies, namely Swartvlei
Lake and Swartvlei estuary. SANParks have been monitoring this estuary closely over the past
two decades, due to its importance to the ecology and to tourism. There are also low-lying
properties on the perimeter of the Swartvlei estuary which run the risk of occasional flooding.
Two of the major monitoring issues in this estuary system are the water level required for
successful mouth breaching, and the influence of the water level on the low-lying properties.
This study presents a preliminary analysis of the sediment budget across the Swartvlei estuary
mouth. The objective of this study was to identify the various sediment contributory factors
and to estimate the quantities that each individually contributed towards the defined sediment
budget. / AFRIKAANSE OPSOMMING: Die Swartvlei meer en see monding is geleë aan die kaapse suidkus van Suid- Afrika. Dit vorm
deel van die kern bewarings area van die Wilderness Nationale Park. Die Swartvlei sisteem
bestaan uit twee verbinde, kern dele nl: Swartvlei meer en estuarium.
Vir die afgelope twee dekades is hierdie area onder die noue toesig van SANParke as gevolg
van die belangrikheid van die area met betrekking tot toerisme en ekologie. Daar is ook
menigde laag liggende eiendomme aan die oewers, wat baie sensitief is vir watervlak stygings.
Die optimum water vlakke benodig vir die uitskuring van die gety monding het ook implikasies
vir die laag liggende eiendome en vereis noukeurige monitering.
‘n Voorlopige analise van die sediment begroting rondom die gety monding word deur hierdie
studie voorgelê.
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