Thesis (MScIng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The moisture content of road foundations plays an important role in the durability of the pavement and the driving comfort of the road. After a pavement has been completed, gradual moisture changes occur in the foundations until equilibrium conditions can be reached, and this can have negative results if expansive clays, for example, are present in the foundation. Pre-wetting of the foundation material is seen as a method to minimilize moisture changes after construction, but if the pavement was already completed, it would be very difficult to change or alter the moisture content in the foundation, because water could then only be applied to the shoulder areas of the road and horizontal infiltration in the soil is exceptionally slow. The research which is reported in this account was undertaken to determine whether the process of electro-osmosis could be applied to accelerate water infiltration underneath covered areas, as in, for example, road foundation layers. Electro-osmosis, if found to be successful, has various advantages, of which the most important is that it can be applied without stopping the normal operations of the road. This research was carried out on a mixture of G5 material (TRH14 classification) and fine material in the form of clay with a low plasticity. Firstly, tests were performed to determine the percentage of fines required. It was found that, if too little fines were present infiltration did not occur, because moisture could flow freely through the openings between the rough aggregate. Electro-osmosis also had no effect on the rate of flow. The allocated amount of fines required to fill sufficient openings was about 30% (TRH14 classification of mixture is G10). Free flow was stopped and true infiltration occurred. Simultaneously, the rate of infiltration could be accelerated with electro-osmosis. Furthermore, a two-dimensional model of a road was constructed with electrodes placed on both sides, with the aim to determine the infiltration pattern controlled by electro-osmosis and what the effect of the initial moisture content would be on the process. Water was introduced to the one side of the model road and the wetting of the foundation was investigated. If the electric current for electro-osmosis was switched off, the infiltration was mainly vertical, as expected, but with the current switched on, there was an obvious acceleration of infiltration in the horizontal direction. As in the case of the initial tests, it was found that electro-osmosis was not very successful to accelerate horizontal infiltration at low percentages of fines. Furthermore, it was obvious that electroosmosis was also more effective if the initial moisture content of the soil was low. Low amounts of fines and high initial moisture contents had rather the electroosmotic flow of water passing underneath the road as a result instead of infiltration acceleration, with the result that the moisture content did not change much. The research thus showed that electro-osmosis is a possible manner in which moisture could be conducted into the foundation layers of roads to increase the moisture content if the appropriate amount of fines and moisture content were present in the foundation material. Further research could still be carried out and the materials in each case should be practically evaluated before this method could be continued with. / AFRIKAANSE OPSOMMING: Die voginhoud van padfondamente speel ’n belangrike rol in die duursaamheid van die plaveisel en die rygerief van die pad. Nadat ’n plaveisel voltooi is, vind daar geleidelike vogverandering in die fondamente plaas totdat ewewigstoestande bereik is, en dit kan nadelige gevolge inhou indien uitsettende kleie byvoorbeeld in die fundament teenwoordig is. Voorafbenatting van die fondamentmateriaal word gereken as ’n metode om vogveranderinge na konstruksie te minimeer, maar indien die plaveisel reeds voltooi is, is dit baie moeilik om die voginhoud in die fondament te verander of beheer omdat water dan slegs buite die skouerareas van die pad toegedien kan word en horisontale infiltrasie in grond uiters stadig is. Die navorsing waaroor hierin verslag gedoen word, is onderneem om te bepaal of die proses van elektro-osmose aangewend kan word om waterinfiltrasie onder bedekte areas, soos byvoorbeeld padfondamentlae, te versnel. Elektro-osmose, indien dit suksesvol blyk te wees, hou verskeie voordele in, waarvan die belangrikste dat dit aangewend kan word sonder om die normale bedryf van die pad te staak. Die ondersoek is uitgevoer op ’n mengsel van G5 materiaal (TRH14 klassifikasie) en fynstof in die vorm van klei met ’n lae plastisiteit. Eerstens is toetse uitgevoer om die persentasie fynstof wat nodig is, te bepaal. Daar is bevind dat, indien te min fynstof teenwoordig is, infiltrasie nie plaasvind nie aangesien water vryelik deur die openinge tussen die growwe aggregaat kan vloei. Elektro-osmose het ook geen effek op die vloeitempo gehad nie. Die aangewese hoeveelheid fynstof om genoegsame openinge te vul was ongeveer 30% (TRH14 klassifikasie van mengsel is G10). Vrye vloei is dan gestuit en ware infiltrasie het plaasgevind. Terselfdertyd kon die tempo van infiltrasie versnel word met elektro-osmose. Voorts is ’n twee-dimensionele model van ’n pad gebou, met elektrodes aan weerskante geplaas, met die doel om te bepaal of die infiltrasiepatroon deur elektro-osmose beheer kon word en wat die effek van beginvoginhoud op die proses sal wees. Water is aan een kant van die modelpad ingevoer en die benatting van die fondament bestudeer. Indien die elektriese stroom vir elektroosmose afgeskakel was, was die infiltrasie hoofsaaklik vertikaal, soos verwag, maar met die stroom aangeskakel was daar duidelike versnelling van infiltrasie in die horisontale rigting. Net soos in die geval van die aanvanklike toetse is bevind dat elektro-osmose nie baie suksesvol was om horisontale infiltrasie te versnel by lae persentasies fynstof nie. Dit het verder geblyk dat elektro-osmose ook meer effektief was indien die aanvanklike voginhoud van die grond laag was. Lae hoeveelhede fynstof en hoë aanvanklike voginhoude het eerder elektroosmotiese deurvloei van water onderdeur die pad tot gevolg gehad as infiltrasieversnelling, met die gevolg dat die voginhoud nie veel verander het nie. Die navorsing het dus getoon dat elektro-osmose ’n moontlike wyse is waarop water in die fondamentlae van paaie ingevoer kan word om die voginhoud te verhoog indien die geskikte hoeveelheid fynstof en voginhoud in die fondamentmateriaal teenwoordig is. Verdere navorsing kan nog uitgevoer word en die materiale van elke geval sal prakties evalueer moet word voordat met die metode voortgegaan kan word.

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008.

Μελετάται η διάδοση της διάρρηξης κανονικού ρήγματος υποβάθρου σε υπερκείμενους μη-συνεκτικούς εδαφικούς σχηματισμούς τόσο για την περίπτωση ελευθέρου πεδίου όσο και για την αλληλεπίδραση με θεμελίωση γειτονικών κατασκευών. Ο κύριος στόχος της διερεύνησης αυτής ήταν η παρουσίαση των κατανομών των γωνιακών παραμορφώσεων, β, και των οριζόντιων ορθών παραμορφώσεων, εxx, υπό συνθήκες ελευθέρου πεδίου, οι οποίες βοηθούν στην αποτροπή ή μετριασμό της επικινδυνότητας πρόκλησης βλαβών στις κατασκευές που εδράζονται στην περιοχή του ρήγματος και σε μικρή απόσταση από αυτό. Αντικείμενο της παρούσας Διατριβής αποτελεί η συστηματική και διεξοδική διερεύνηση της βιβλιογραφίας στο αντικείμενο της διάδοσης της σεισμικής διάρρηξης σε εδαφικούς σχηματισμούς καθώς και της αλληλεπίδρασής της με τη θεμελίωση γειτονικών κατασκευών, η παρουσίαση της απλοποιημένης μεθοδολογίας των Αθανασόπουλος και Λεωνίδου (2003) για τη μελέτη του προβλήματος των επιπτώσεων της σεισμικής διάρρηξης στην ακεραιότητα γειτονικών κατασκευών και η διεξαγωγή κατάλληλων παραμετρικών διερευνήσεων στα αποτελέσματα των αναλύσεων. Επίσης, διερευνήθηκε η αξιοπιστία της απλοποιημένης μεθόδου, διαμέσου συγκρίσεων με δημοσιευμένα αποτελέσματα πειραματικών και υπολογιστικών ερευνών. Τέλος, παρουσιάστηκε μία προτεινόμενη απλοποιημένη μεθοδολογία για την αλληλεπίδραση της διάδοσης της διάρρηξης κανονικού ρήγματος με τη θεμελίωση έργων που βρίσκονται στο εσωτερικό της ζώνης επιρροής. Για την πληρέστερη επεξήγηση της προτεινόμενης απλοποιημένης μεθοδολογίας, παρουσιάστηκε ενδεικτικά η εφαρμογή της για τον προσδιορισμό της γωνίας στροφής (κλίσης) αβαθούς θεμελίωσης, στη ζώνη επιρροής της διάδοσης της διάρρηξης ρήγματος, και πραγματοποιήθηκε σύγκριση με δημοσιευμένα αποτελέσματα δοκιμών σε φυγοκεντριστή και αριθμητικών αναλύσεων. / The Thesis is focused on normal fault rupture propagation through cohesionless soil in free-field conditions and the interaction with buildings foundations.

Στην παρούσα διατριβή, η οποία πραγματεύεται τις θεμελιώσεις κατασκευών, πρωτίστως αναφέρονται οι προδιαγραφές που οφείλονται να τηρούνται ως προς την ασφάλεια και τη λειτουργικότητα της ανωδομής. Γίνεται αναφορά στη σπουδαιότητα της γεωτεχνικής έρευνας και στους τρόπους και τις μεθόδους με τις οποίες αυτή διεξάγεται. Στη συνέχεια ορίζονται τα κριτήρια σχεδιασμού μιας θεμελίωσης, δηλαδή το πρόβλημα αστοχίας και το πρόβλημα λειτουργικότητας. Παρατίθενται τρόποι υπολογισμού της φέρουσας ικανότητας για διάφορες εδαφικές συνθήκες για αβαθείς θεμελιώσεις, καθώς και ο υπολογισμός συντελεστών ασφαλείας με κλασικές μεθόδους καθώς και κατά τον Ευροκώδικα EC-7. Σχετικά με τις καθιζήσεις, αναφέρονται οι κατηγορίες τους και γίνεται υπολογισμός ανά περίπτωση και τύπο εδάφους, ενώ σημειώνονται και τα αποτελέσματα τους στις κατασκευές. Επίσης, συνοψίζονται τα επιτρεπόμενα όρια των καθιζήσεων. Ακολουθούν μεθοδολογίες για το σχεδιασμό των τριών τύπων αβαθών θεμελιώσεων, δηλαδή για μεμονωμένα θεμέλια, πεδιλοδοκούς και γενική κοιτόστρωση με γνώμονα να πληρούνται τα κριτήρια σχεδιασμού. Έπειτα περιγράφονται οι βαθιές θεμελιώσεις, καθώς και οι τρόποι υπολογισμού της φέρουσας ικανότητας τους και των καθιζήσεων που προκαλούν. Γίνονται εφαρμογές διάφορων μορφών θεμελιώσεων, για μια διώροφη οικοδομή, σε δύο διαφορετικές και χαρακτηριστικές περιοχές της πόλης των Πατρών με δεδομένα από δειγματοληπτικές γεωτρήσεις. Η πρώτη περιοχή αφορά το ανατολικό τμήμα της πόλης (περιοχή στρατοπέδου ΚΕΤΧ) όπου επιφανειακά συναντάται στρώμα σκληρής πολύ αμμώδους αργίλου και σχεδιάζεται επιφανειακή θεμελίωση με εναλλακτικούς τρόπους. Η δεύτερη περιοχή αφορά την παράκτια ζώνη της πόλης, όπου συναντάται επιφανειακό στρώμα μαλακών εδαφών σημαντικού πάχους και γίνεται διαστασιολόγηση για βαθειά θεμελίωση έγχυτων πασάλων τριβής. / At first, in this thesis, which deals with foundations in constructions, there is a mention for specifications required to ensure both safety and functionality of the structure. Also, there is a reference in geotechnical investigation and methods importance. Additionally, designing criteria for foundations are defined as both “failure matter” and “ functionality (settlements) matter”. Formulas and methods of calculating bearing capacity of shallow foundations for different territory types are listed. There are also methods for calculating factors of safety (classical methods, Eurocode EC-7). There is a reference in settlement categories and the way of calculating settlement value regarding their type and the soil environment. Allowable limits of settlements are summarized, as well. Thereafter, there are analyzed the ways of designing all shallow foundation types, which are individual footings, spread footings and raft foundation, so as designing criteria are met. Deep foundations are described, as well as methods of calculating their bearing capacity and settlement value. Finally, different foundation applications are presented as possible solutions, for a two storey building structure, in two different and characteristic areas in Patras. Data have been exported from sample drillings. The first area, is located in Eastern Patras, (camp of KETEX), where there is a surface soil layer of hard, very sandy clay. There, it is designed shallow foundation in variable and alternative ways. The second area, is located in the coastal zone of Patras, where there is a surface quit thick layer of soft deposits. There, the building construction is being based by designing concrete injector piles.

published_or_final_version / abstract / Earth Sciences / Doctoral / Doctor of Philosophy

Community college students are being forced to delay future educational goals, due to the lack of financial support. Grants, student loans and financial aid support from government sources are in short supply. While past resources from state legislative bodies are being restricted and have been reduced to historic levels; educational organizations –community college foundations - have had to associate themselves with numerous outside sources. Collaborative partnerships with business, government, and industry have helped to relieve financial short- falls and student scholarship pressures while building long term and sustaining relationships. The purpose of this study was to investigate the process of annual giving within Texas Gulf Coast Community Colleges. A framework for the study was structured inside of five different institutions in the Gulf Coast region. Additionally, this study set out to examine the overall context of annual giving and whether college foundations were utilizing annual giving as a relationship tool for development and fundraising purposes. The research design followed an interview, case study format utilizing qualitative data. The study had several major findings. First, all colleges adhere to inputs, processes, and outputs. Second, by analyzing each of the inputs and processes, a set of output relationships- were discovered. Third, all institutions have a set of functions – financial, organizational, operational, and structural – which are in alignment with inputs, process and outputs. Fourth, brand identity helps to integrate donors and thereby, builds sustained and long-term support. Annual giving within Texas Gulf Coast community colleges has become a major fixture as a fundraising practice. Foundations are making the most of this tool by positioning themselves with their community and thus, reaping the benefits of donor relationships. / text

The Mw 6.2 February 22nd 2011 Christchurch earthquake (and others in the 2010-2011 Canterbury sequence) provided a unique opportunity to study the devastating effects of earthquakes first-hand and learn from them for future engineering applications. All major events in the Canterbury earthquake sequence caused widespread liquefaction throughout Christchurch’s eastern suburbs, particularly extensive and severe during the February 22nd event. Along large stretches of the Avon River banks (and to a lesser extent along the Heathcote) significant lateral spreading occurred, affecting bridges and the infrastructure they support. The first stage of this research involved conducting detailed field reconnaissance to document liquefaction and lateral spreading-induced damage to several case study bridges along the Avon River. The case study bridges cover a range of ages and construction types but all are reinforced concrete structures which have relatively short, stiff decks. These factors combined led to a characteristic deformation mechanism involving deck-pinning and abutment back-rotation with consequent damage to the abutment piles and slumping of the approaches. The second stage of the research involved using pseudo-static analysis, a simplified seismic modelling tool, to analyse two of the bridges. An advantage of pseudo-static analysis over more complicated modelling methods is that it uses conventional geotechnical data in its inputs, such as SPT blowcount and CPT cone resistance and local friction. Pseudo-static analysis can also be applied without excessive computational power or specialised knowledge, yet it has been shown to capture the basic mechanisms of pile behaviour. Single pile and whole bridge models were constructed for each bridge, and both cyclic and lateral spreading phases of loading were investigated. Parametric studies were carried out which varied the values of key parameters to identify their influence on pile response, and computed displacements and damages were compared with observations made in the field. It was shown that pseudo-static analysis was able to capture the characteristic damage mechanisms observed in the field, however the treatment of key parameters affecting pile response is of primary importance. Recommendations were made concerning the treatment of these governing parameters controlling pile response. In this way the future application of pseudo-static analysis as a tool for analysing and designing bridge pile foundations in liquefying and laterally spreading soils is enhanced.

Under static of dynamic loadings, the junction (interface) between a structure-foundation system can experience contact, slip, separation and rebonding modes of deformations. Two interface models are proposed for simulation of interface behavior in finite element analysis of dynamic soil-structure interaction problems. The first element called the thin-layer element has (small) finite thickness. Geometrically, this element is similar to the continuum (soil or structural) element; however, its constitutive relations are defined differently. The normal behavior is defined as a function of the material properties and stress-strain characteristics of the neighboring continuum element. The shear behavior is defined in terms of observed shear stress-relative displacement behavior expressed as function of factors such as normal stress, number of cycles of loading and amplitude of load (or displacements). Mohr-Coulomb criterion is used to define activated sliding strength of interface. Modes of deformations are simulated by using appropriate stress redistribution iterative schemes. The second model called the mixed interface element has zero thickness. Both displacements and tractions are treated as primary unknowns. Constraints associated with modes of deformations are included using a variational approach. An incremental solution scheme is proposed. Material parameters related to the proposed models are evaluated from the results of sand-concrete interface tests in a Cyclic Multi-Degree-of-Freedom shear device. Accuracy of the proposed models are verified with respect to a number of example problems. In general, consistent and satisfactory results are obtained. For further verification and evaluation of these models, several soil-structure interaction problems are solved and detailed results are presented. It is observed that behavior of structure-foundation systems can be significantly influenced by interface conditions. An analysis based on bonded interface condition appears to underestimate actual response. Hence, it will be appropriate to include interface behavior in the analysis and design of structures subjected to dynamic and earthquake loadings.

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Description logics (DLs) are knowledge representation formalisms with well-understood model-theoretic semantics and computational properties. The DL SROIQ provides the logical underpinning for the semantic web language OWL 2, which is quickly becoming the standard for knowledge representation on the web. A central component of most DL applications is an efficient and scalable reasoner, which provides services such as consistency testing and classification. Despite major advances in DL reasoning algorithms over the last decade, however, ontologies are still encountered in practice that cannot be handled by existing DL reasoners. We present a novel reasoning calculus for the description logic SROIQ which addresses two of the major sources of inefficiency present in the tableau-based reasoning calculi used in state-of-the-art reasoners: unnecessary nondeterminism and unnecessarily large model sizes. Further, we describe a new approach to classification which exploits partial information about the subsumption relation between concept names to reduce both the number of individual subsumption tests performed and the cost of working with large ontologies; our algorithm is applicable to the general problem of deducing a quasi-ordering from a sequence of binary comparisons. We also present techniques for extracting partial information about the subsumption relation from the models generated by constructive DL reasoning methods, such as our hypertableau calculus. Empirical results from a prototypical implementation demonstrate substantial performance improvements compared to existing algorithms and implementations.