Dissertations / Theses on the topic 'Geotechnical engineering'
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1
Faria, P. de D. "Shakedown analysis in geotechnical engineering." Thesis, Swansea University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636956.
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Many problems in geotechnology are concerned with the response of earth materials to cyclic loads. These loads are either generated by forces of nature such as sea waves, currents, winds, and earthquakes or as a consequence of engineering operations such as blasting, pile driving and rotating machines. For most design purposes related to static loads it is logical to use as a design basis either the elastic range where no plastic deformation occurs or the plastic range, in which large plastic deformation can occur. However, when cyclic loading is involved few design methods are available since a pattern for the response of the body to cyclic loads is not well known. When a body is subjected to cyclic loading some modes of adaptation or non adaptation can occur as a response to the loads such as elastic shakedown, alternating plasticity and ratchetting. Despite its extensive use in structural problems very few applications of the shakedown approach to soil masses can be found in literature. Therefore the present work aims to extend the elastic shakedown concepts to geotechnical problems. Initially the shakedown concepts are introduced, its theorems and their importance for geomechanical problems are highlighted. Later the use of Melan's static shakedown theorem for the present study is shown. Shakedown analyses of plane stress and plane strain problems are presented. In this study the shakedown formulation is based on the concept of a residual stress field obtained by means of a numerical formulation using a visco-plastic algorithm. Two numerical codes linked with a mesh generator were implemented as tools for the treatment of the shakedown problems. Numerical examples and applications are shown to illustrate the usefulness of the present approach.
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Davey-Wilson, Ian Edward George. "A knowledge-based system in geotechnical engineering." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277162.
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Kobayashi, Shun-ichi. "Limit and Shakedown Design in Geotechnical Engineering." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/148311.
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Ouyang, Yue. "Geotechnical behaviour of energy piles." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708099.
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Bao, Yu. "A Biot formulation for geotechnical earthquake engineering applications." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219029.
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Shah, Janvi Pankaj. "Resilient geotechnical asset management." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6644/.
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There is overwhelming evidence that the development of new, technically sound, engineered and fit-for-purpose critical physical infrastructure is vital for economic growth and stability. With many countries targeting significant levels of capital investment in energy, transport, communications, flood management and water and waste water infrastructure, there is a vital need for asset management frameworks that can provide both robust and resilient asset support. Currently, asset management tools focus predominantly on data management, deterioration modelling, condition assessment, risk, as well as economic factors (such as whole-life costing and developing investment plans). Some also consider the vulnerabilities of a network to climate change and extreme weather events such as flooding. However, rather than taking a long term view, asset management strategies are often short term, typically five years or less. What is needed is a long-term approach, which will ensure assets are safe, secure and resilient to what the future may hold in 20, or even 50 years’ time. The thesis describes the development of a ‘Resilience Assessment Framework’ which provides a platform to appraise resilience of geotechnical assets in the planning stage of asset management by considering how geotechnical assets (specifically for transport infrastructure) designed and built today will perform in the light of socio-economic, environmental, political, technological changes and shock events in the future. This framework intends to assist in strategic level decision-making by enabling long term planning and management of geotechnical assets and help future proof transport infrastructure. The proposed framework is validated using two real case studies to demonstrate its use and applicability in the field of geotechnical asset management.
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Holt, Daniella Godinho Abreu. "Sustainable assessment for geotechnical projects." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/3034/.
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Geotechnical engineering has a crucial role to play in enhancing sustainability due to its pivotal role in the construction process where potentially impacts are highest. Currently, there is a lack of methodologies for assessing geotechnical projects that truly encompass the three core pillars of sustainability. A robust system is required which offers an holistic approach that is both flexible and easily understood, whilst not being biased towards rewards or is prohibitively costly. In addition, ‘tool fatigue’, whereby a system is generated but never used, must be avoided. After a detailed evaluation of the systems available, the SPeAR® framework was selected. Following detailed discussion with a variety of practitioners, the methodology was significantly adapted to make it applicable to geotechnical problems and ensure that geotechnical engineers can understand and use it with relatively ease. The new version, called ‘GeoSPeAR’ in this thesis, allows for greater communication between masterplanning and geotechnical engineering via their common base, thus avoiding a potential barrier to greater adoption of more sustainable practices through the construction cycle. Three case studies demonstrated the assessment of the ‘GeoSPeAR’ methodology. These showed the practical application of the system and how this effectively supports geotechnical engineers in embedding sustainability into projects.
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Brimicombe, A. J. "The application of geomorphological triangular databases in geotechnical engineering." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31207157.
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Oliphant, J. "Controlling safety and capturing engineering judgement in geotechnical design." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381407.
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McCombie, Paul F. "Some developments of limit equilibrium analyses in geotechnical engineering." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501625.
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Four journal papers have been selected from the candidate's published research output, to represent his work in developing analytical methods for use in geotechnical engineering design and analysis. Two of the papers contribute to significant advances in the understanding of the behaviour of dry-stone retaining walls, which will lead to greater confidence in the assessment of existing walls and the design of new walls. The other two papers develop optimisation and analysis routines with the aim of supporting the assessment of slope stability, and the design of new cut and built slopes and stabilisation works.
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Bundy, Stephen. "Geotechnical properties of chalk putties." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/geotechnical-properties-of-chalk-putties(29af3b60-00c7-4507-8c17-24b50f5cf8b5).html.
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Chalk putties are common in Southern England, occurring naturally and as a result of earthworks in intact chalk. The ease and readiness with which intact chalk breaks down into putty makes establishing a good geotechnical profile of the material necessary. A review of literature indicates that previous laboratory studies on chalk putties are limited, and that testing of the material has proven difficult using standard procedures. This study initially quantifies index parameters such as Atterberg limits, thixotropy and particle size distribution before considering susceptibility to age-related strength gains and shear strength-strain dependency so that subsequent shear test data can be normalised. Contrary to literature, age-related strength gains were found to be minor, whilst shear strength-strain dependencies were found to be significant. Large strain tests in ring shear apparatus (following recommended test procedures) found non linearity in the drained shear failure envelopes, with effective friction angles (Ø') increasing with strain. This non linearity is explained by sample grading evolution. Using these findings the study develops new preparation and testing methodologies to create ‘identical soils’ of known stress history. Testing in a computer governed stress path cell (using ‘Triax’ software) found that chalk putty behaves as a contractive material, ‘wet’ of its critical state, exhibiting failure by liquefaction for mean effective stresses (p') lower than 200kPa. Pre and post yield permeability values in the range 2.5-13 x 10-9m/s were recorded with state parameters indicating a constant a pre shear p' of between 0 and 400kPa.
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Welling, Gary E. "Engineering Performance of Polymer Amended Soils." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/856.
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A laboratory test program was undertaken to evaluate a series of engineering properties over a range of soil types; amendment types and addition rates; and moisture contents to enhance understanding of the engineering significance of polymer amendment. Four soils were manufactured and tested with varying ranges of fines and plasticity. A proprietary elastic copolymer was tested at addition rates of 0.5% to 2.5% (dry weight basis). Cement was tested at addition rates of 1% to 4%. Lime was tested at an 8% addition rate. Water addition rates ranged from 4% dry of optimum to 4% wet of optimum. Engineering properties determined throughout the test program included dry unit weight / moisture content relationships through compaction tests; shear strength through unconfined compression strength tests and direct shear tests; durability through freeze-thaw and wet-dry durability tests; and stiffness through resilient modulus tests and through interpretation of the unconfined compression and direct shear test results.
The addition of polymer altered the optimum moisture content of the soils. Change in optimum moisture content ranged from 0.51 to 1.27 times the control water demand. The dry unit weight of polymer amended specimens ranged from 0.97 to 1.01 times their respective control dry unit weight. The peak strength of polymer amended specimens ranged from 1.02 to 18.4 times the control strength. The peak wet-dry and freeze-thaw durability of polymer amended specimens ranged from 6.8 to 10.8 times the control durability. The addition of polymer increased the peak initial stiffness of specimens to approximately 3 times the control stiffness. However, the stiffness was reduced to 0.68 times the control stiffness with dynamic repeated loading through the resilient modulus test.
The polymer addition rate required to achieve peak engineering performance ranged from 0.5% to 2.5%, based on soil type. Polymer modified the engineering properties of soil through physical bonding. The amount of polymer required to modify the engineering properties was directly related to specific surface and soil particle coating thickness. It was determined that polymer amendment had an optimal addition rate that resulted in the greatest increase in engineering parameters. The addition rate was optimum when polymer was applied at rates high enough to sufficiently coat all soil particle surfaces, but at rates low enough that it did not cause additional particle separation.
Overall, polymer amendment of soil improved or maintained all tested engineering parameters, except the resilient modulus, of all soils. Polymer amended soils displayed a reduced performance compared to cement amended soils, and an improved performance compared to lime amended soils.
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Smith, Alexander D. "Computerized modeling of geotechnical stratigraphic data." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14360.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1989.Archives copy bound in 1 v.; Barker copy in 2 v.
Includes bibliographical references (leaves 246-251).
by Alexander Donnan Smith.
Ph.D.
14
Laudahn, Andreas. "An approach to 1g modelling in geotechnical engineering with soiltron." Berlin Logos-Verl, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2704424&prov=M&dok_var=1&dok_ext=htm.
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Fratta, Dante. "Passive and active measurement of unique phenomena in geotechnical engineering." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20703.
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Mukhtar, Jonathan-Adam. "Engineering Geological and Geotechnical Characterisation of Selected Port Hills Lavas." Thesis, University of Canterbury. Geological Sciences, 2014. http://hdl.handle.net/10092/9971.
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This thesis aims to create a specific and robust geotechnical data set for the Lyttelton Volcanic Group, and investigate the effect of emplacement and post-emplacement mechanisms on geotechnical characteristics. The thesis provides an engineering geological model of a representative section of the Lyttelton Volcanic Complex, which, in conjunction with field observations, informed the subdivision of the main lithological groups into geotechnical sub-units.
The sub-units account for the geological variations within the rock types of this study. Eighteen geotechnical sub-units were identified, sampled and characterised: 1trachytic dykes, 2trachytic domes, 3trachytic lava, 4brecciated basaltic ignimbrite, 5moderately welded basaltic ignimbrite, 6highly welded basaltic ignimbrite, 7red ash, 8crystal dominated tuff, 9lithic dominated tuff, 10rubbly basaltic breccia, 11unweathered basaltic lava, 12slightly to moderately weathered basaltic lava, 13highly to completely weathered basaltic lava, 14highly vesicular basaltic lava bomb, 15basaltic dyke, 16blocky basaltic lava, 17volcanogenic conglomerate and 18volcanogenic tuffaceous sandstone. Thirteen units were able geotechnically tested. Sample preparation and geotechnical testing followed ASTM and ISRM guidelines respectively. Geotechnical testing included: uniaxial compressive strength (σci), point load strength index (Is(50)), porosity (n), density (ρd), P and S wave velocities (Vp and Vs), slake durability (Id2), Young’s Modulus (E), Poisson’s Ratio (υ), shear modulus (G) and bulk modulus (K). The igneous lithologies included in this study have been characterised using the Detailed Engineering Geological Igneous Descriptive Scheme, developed purposely for the needs of the thesis.
The results of laboratory testing showed many strong trends with geological characteristics and relationships between geotechnical parameters. Parameters such as porosity, density, P-wave velocities, Young’s Modulus and point load strength showed very strong correlations with uniaxial compressive strength. Variability in the physical and mechanical properties is attributed to the geological factors, which dictate the material behaviour. These include texture, grain size, composition, welding, lithification, flow banding, percentage and size of phenocrysts/clasts/lithics. Geological factors affecting geotechnical behaviour are a function of emplacement mechanism. Four distinct emplacement mechanisms were identified in this study: lava flows, pyroclastic density currents, intrusions (dykes) and airfall deposits. Typically, lava flows and intrusions have higher strength, durability, density and lower porosity than pyroclastics and airfall deposits. Importantly, the data illustrates a considerable variability in some geotechnical parameters within the same unit (e.g. 58-193 MPa strength variation in the unweathered basaltic lava). Variability within rocks with similar emplacement mechanisms is attributed to the effects of post-emplacement mechanisms and processes (e.g. weathering, alteration and micro/macro fracturing leading to lower strength).
Evaluation of engineering geological and geotechnical parameters of rock and soil materials are required for engineering purposes, specifically when any form of design is required. This study has highlighted the importance and necessity to identify volcanic lithologies and features correctly as there are consequences for geotechnical behaviour, and that volcanic data from literature data should not be used without the correct degree of ground-truthing and geological context. Location-specific engineering geological data are necessary for the quantitation of variability in engineering geological characterisation for engineering geological models, designs and simulations in the Port Hills Volcanics.
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Lam, Carlos. "Properties and applications of polymer support fluids in geotechnical engineering." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:ba0867c6-eb42-4b9a-a400-b464749855c5.
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Synthetic polymer fluids have been used as an alternative to conventional bentonite slurries for the excavation of foundation elements over the last two decades. Thus far their use has excited polarised views in the industry – some construction professionals avoid using them after hearing ‘horror stories’ about past failures whereas others believe that they are the future of support fluids because of the many benefits that they can offer. This situation has been found to be mainly due to a lack of understanding of what polymers really are and their properties. To address this issue, the various polymer products currently available in the market have been categorised based on their intended functions, and the fundamental properties of some of them have been characterised. The research showed that significant difference exists between polymers even of the same chemical family. Based on a series of rheological experiments, it was found that the properties of polymer fluids are highly dependent on the governing shear rate, time, and a range of site dependent factors. The research also showed that the current procedure for the interpretation of viscosity data is incorrect. After an analysis of the properties of currently available polymers, the latter part of the thesis describes a field trial carried out at a site in Stratford, East London. The aims of the trial were twofold: to compare the performance between piles constructed using bentonite and polymer fluids, and to assess the effect of extended pile bore open time for pile bores supported by polymers. From the results, it was found that the polymer piles showed much stiffer load–settlement response than the bentonite pile, and that a pile bore open time of up to 26 h had no adverse effect on the pile performance. The load test results have been carefully back-analysed using a range of methods. It was found that, compared to their bentonite counterparts, polymer fluids can improve the interface shearing resistance with Thanet Sand and the shear modulus of the Lambeth clay.
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Kim, Carl Chong-Soo. "Geotechnical aspects of recirculating well design." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/44495.
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Day, Peter William. "A contribution to the advancement of geotechnical engineering in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79868.
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Thesis (DEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Geotechnical engineering is a relatively young field of engineering and one in which there are still many unanswered questions and gaps in our knowledge. Added to this, the geotechnical materials on each new site on which geotechnical work is undertaken are the unique product of many influences including geology, geomorphology, climate, topography, vegetation and man. There is thus plenty of scope for innovation. This dissertation describes the contributions made to Geotechnical Engineering in South Africa by the Candidate over a period of close on 40 years. It describes the three-step process followed in the majority of these contributions. Step one is the identification of a problem that requires investigation, the application of new techniques or simply the consolidation of existing knowledge. Step 2 is the investigation of the problem and the development of a solution. Step 3 is sharing the outcome of this work with the profession by means of publications, by presentations at seminars and conferences or by incorporation into standards / codes of practice. Part 1 of the dissertation describes the exciting environment in which geotechnical engineers operate. This environment is characterised by openness and cooperation between practitioners of geotechnical engineering, be they geotechnical engineers, engineering geologists, contractors, suppliers or academics. This part also explores the parallels in the roles played by academics and practitioners and how each can contribute to the advancement and dissemination of knowledge. Part 2 describes contributions made in various fields including problem soils (dolomites, expansive clays, uncompacted fills, etc.), lateral support, pile design and construction, health and safety, and cooperation with international organisations. Part 3 describes the Candidate's involvement in the introduction of limit states geotechnical design into South African practice culminating in the drafting of SANS 10160-5 on Basis of Geotechnical Design and Actions. It also describes the Candidate's work with the ISSMGE Technical Committee TC23 dealing with limit states design. Part 4 deals with the Candidate's contribution to other codes and standards and his role on various committees of the Engineering Council of South Africa and the South African Bureau of Standards. The final part of the dissertation provides an overview of the process followed in making such contributions, highlighting the role played by curiosity and a desire to share the knowledge gained with others in the profession. It continues by identifying work that still needs to be done in many of the areas where contributions have been made and concludes with a statement of what the candidate would still like to achieve during the remainder of his career. The Candidate gratefully acknowledges the generous opportunities afforded to him by his colleagues at work and the invaluable guidance and mentorship received from fellow professionals in academia and practice.
AFRIKAANSE OPSOMMING: Geotegniese ingenieurswese is 'n relatiewe jong wetenskap en een met vele kennisgapings en waarin daar nog talle vrae onbeantwoord bly. Daarby is geotegniese materiale uniek tot elke terrein waarop werk aangepak word en die produk van 'n kombinasie van prosesse; insluitend geologie, geomorfologie, klimaats toestande, topografie, plantegroei en menslike aktiwiteite. Daar is dus nog ruim geleentheid vir innoverende bydraes. Hierdie verhandeling beskryf die Kandidaat se bydraes tot Geotegniese Ingenieurswese in Suid-Afrika oor die afgelope 40 jaar. Dit beskryf 'n drie-voudige benadering wat in die meeste van die bydraes gevolg is. Die eerste stap is om die probleem te definieer en te omskryf in terme van die ondersoek wat geloods moet word, asook die noodsaaklikheid vir die ontwikkeling van nuwe tegnologie teenoor die konsolidasie van bestaande inligting. Tydens die tweede stap word die probleem ondersoek en 'n oplossing ontwikkel. Die derde stap is om die resultate te deel met die geotegniese bedryf by wyse van publikasies, voorleggings by konferensies en seminare, en insluiting in praktykkodes en standaarde. Deel 1 beskryf die opwindende werksomstandighede waarbinne geotegniese ingenieurs hul bevind. Dit word geken aan die ope samewerking tussen belanghebbende partye; onder andere ingenieurs, ingenieursgeoloë, kontrakteurs, verskaffers en akademici. Deel 1 beklemtoon ook die parallelle rolle wat vertolk word deur akademici en praktiserende ingenieurs en hoe beide partye bydraes maak tot die ontwikkeling en verspreiding van tegnologie. Deel 2 beskryf die Kandidaat se bydraes tot verskeie navorsingsvelde; waaronder probleemgrondtoestande (dolomiet, swellende kleie, ongekonsolideerde opvullings ens.), laterale ondersteuning, ontwerp en konstruksie van heipale, beroepsveiligheid, en samewerking met internasionale organisasies. Deel 3 beskryf die Kandidaat se betrokkenheid by die bekendstelling van limietstaat geotegniese ontwerp in die Suid-Afrikaanse bedryf wat uitgeloop het op die samestelling van SANS 10160-5 Basis of Geotechnical Design and Actions. Dit beskryf ook die Kandidaat se samewerking met die ISSMGE Technical Committee TC23 wat te make het met limietstaat ontwerp. Deel 4 beskryf die Kandidaat se bydraes tot ander kodes en standaarde en die rolle wat hy vertolk het op verskeie komitees van die Suid-Afrikaanse Raad vir Ingenieurswese asook van die Suid-Afrikaanse Buro van Standaarde. Die laaste deel van die verhandeling bied „n oorsig oor die proses wat gevolg is in bostaande bydraes met die klem op die rol van weetgierigheid en die begeerte om sulke kennis te deel met ander belanghebbendes. Om af te sluit, identifiseer die Kandidaat oorblywende tekortkominge in baie van die vraagstukke waar hy bydraes gelewer het en gee 'n opsomming van wat hy graag nog sal wil bereik tydens die verdere verloop van sy loopbaan. Die Kandidaat gee met dank erkenning aan sy kollegas vir die ruim geleenthede wat hom gebied is en die waardevolle leiding en mentorskap wat hy ontvang het van mede praktiserende ingenieurs en akademici.
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Wang, Zhe. "Numerical simulations of geotechnical engineering problems considering the principal stress rotation." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32610/.
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Soil behaviors are quite complex under dynamic loadings, such as wave loading, earthquake loading, etc, but they share common characteristics that the soil is subjected to considerable principal stress rotations (PSR). PSR can generate plastic deformation even without a change of principal stress magnitudes. Continuous PSR can also generate excess pore water pressures and cumulative shear strains in undrained condition. Therefore, the PSR from the dynamic loadings can accelerate undrained soil liquefaction because it can cause cumulative plastic volumetric deformations. Ignoring PSR induced deformation may lead to unsafe design. It is therefore important to understand the soil behaviors under cyclic loadings with the PSR and take account of this PSR impact in the numerical simulations of corresponding geotechnical problems. Although researchers have recognized the importance of the PSR in real geotechnical problems under diverse loading conditions and conducted extensive experimental studies, there are limited considerations of the PSR impact on numerical simulations of boundary value problems. Moreover, most of the constitutive models widely-used in the numerical investigations at present cannot simulate this PSR behavior properly. Therefore, a new kinematic hardening soil model (PSR model) developed on the basis of a well-established model with bounding surface concept is used to simulate the PSR behavior in this research. It can take account of the PSR impact by treating the stress rate generating the PSR independently. To investigate the impacts of PSR in numerical simulations of geotechnical problems, the PSR model is implemented into both the single element and finite element analysis of a series of geotechnical problems by a constitutive model subroutine written in Fortran. In this subroutine, an explicit substepping integration algorithm with automatic error controls is used to perform the constitutive formulations. The imposed strain increment can be automatically divided and the sizes of the sub-increments are also automatically determined based on the prescribed error tolerance in this numerical integration scheme. The single element analyses include the simulations of the triaxial and hollow cylinder tests with monotonic, rotational and torsional loading paths, while the finite element analyses consist of the simulations of the centrifuge experimental tests under wave loadings and earthquake loadings. The predicted results by using the soil model with and without considering the PSR impact, as well as the experimental results will be compared. From these single element and finite element analyses, it is evident that the rotational, torsional and dynamic loadings such as wave and earthquake loadings can produce the PSR and non-coaxiality in the soil. The comparisons between the predicted results from the modified PSR model, the original model, and the laboratory results from these experimental tests all show that although the original model can reflect some non-coaxiality, it can produce very limited build-up of pore water pressure and cumulative shear strain under cyclic loading path. However, due to consideration of the PSR impact, the modified PSR model can generate higher pore water pressure and shear strain than the original model, thus bringing the soil to the liquefaction and agrees better with the experimental results. Therefore, it is important to consider the PSR effect in the simulation of geotechnical problems such as wave-seabed interactions and the earthquake induced liquefactions, and the PSR model presented in this research has a great ability and plays an important role in these numerical simulations.
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Wyatt, Timothy Robert. "Development and evaluation of an educational software tool for geotechnical engineering." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20225.
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Sun, Tek-kei, and 孫廸麒. "Numerical modeling of skin friction and penetration problems in geotechnical engineering." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/195991.
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Numerical modeling using finite element method (FEM) is well-recognized as a powerful method for both engineers and researchers to solve boundary value problems. In the modeling of geotechnical problems, the analyses are often limited to simple static problems with either steady-state effective or total stress approach while the transient response (development and dissipation of excess pore water pressure, uex) is seldom considered. Besides, infinitesimal small soil deformation is usually assumed. The simulation is further complicated when the soil-structure interaction problems involve significant soil displacements; like a pile subject to negative skin friction (NSF) and a cone/pile penetration. However, conventional FEM analysis prematurely terminates due primarily to excessive mesh distortion. One could see that simulating a transient problem with large deformation and distortion remains a great challenge. In this study, advanced FE simulations are performed to give new insights into the problems of (1) a pile subject to NSF; and (2) a cone penetration. The transient response of the NSF problem is modeled with the fluid-coupled consolidation technique and geometric nonlinearity. The fluid-coupled cone penetration problem is modeled with a newly developed adaptive approach.
The NSF and cone penetration simulations involve complex soil-structure interface modeling. Two types of modified interface responses are developed and verified which consider fluid coupling. The developed algorithm is applied to back analyze a case history of a pile subject to NSF induced by surcharge loading. Promising results were shown. Development of dragload and neutral plane (NP) with time is studied. NP locates at 75% of the pile embedded length (D) in long-term. Next, a parametric study is performed to investigate the influences of pile geometries, ground compressibility and loading conditions towards the pile responses. The long-term NP locates at around 0.55D to 0.65D in the studied engineering scenarios. The maximum downdrag can be up to 10% of the pile diameter. NP shifts upward when the head load increases. A simple design chart is proposed which helps engineers to estimate the long-term axial load distribution. An illustrative example is given to demonstrate the application and performance of the chart.
The study is extended to investigate the cone penetration problem. An advanced adaptive method is developed and implemented into the FE package ABAQUS to resolve the problems of numerical instability, excessive mesh distortion and premature termination. The proposed method is verified by modeling a ground consolidation problem. Next, total stress back analysis of cone penetration is conducted with the proposed method. The development of cone factor predicted by the proposed method gives a better match with the laboratory result when comparing with the built-in ALE method. Next, the development and dissipation of uex during cone advancing with the proposed method and fluid-coupled technique is investigated. uex develops dramatically around the cone tip. The soil permeability is back calculated from the dissipation test and agrees well with the input value. It is believed that the construction effects of a press-in pile and the subsequence NSF on that pile can be modeled by utilizing the finding of this study.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
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Abd, Al Ghaffar Mona Ahmed Albasheer. "Risk assessment in geotechnical engineering with specific reference to embedded structures." Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/349.
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Ng, Iok Tong. "Geotechnical site characterization based on SPT." Thesis, University of Macau, 1999. http://umaclib3.umac.mo/record=b1445031.
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Edeskär, Tommy. "Use of tyre shreds in civil engineering applications : technical and environmental properties." Doctoral thesis, Luleå tekniska universitet, Geoteknologi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16907.
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End-of-life tyres are a disposal problem regarding the large volumes produced every year. Tyre shreds are primarily produced to reduce the transportation volumes of end-of-life tyres after collection. Within the European Union, there is a ban for landfilling tyre material in order to reduce the total landfilling volumes and to encourage recycling measures. Until recently the main disposal option has been energy recovery in industrial processes. However, legislation acts has recently been taken in the European Union to encourage recycling and recovery of end-of-life-tyres and re-use of tyre materials in construction works is listed as one disposal option.Tyre shreds possess interesting technical properties that could be beneficially used in civil engineering applications. Some characteristic properties of tyre shred materials are the low density, high elasticity, low stiffness, high drainage capacity and high thermal insulation capacity. These properties open up possibilities for utilisation of the material in an innovative manner.The overall aim of this thesis work has been to describe and evaluate tyre shreds as a civil engineering construction material from environmental and technical point of view. The thesis work has included laboratory tests and full scale field tests to investigate technical and environmental properties of tyre shreds and to investigate the tyre shred material behaviour in a real road construction. Furthermore, the state-of-the-art knowledge in the area has also been analysed and presented.In the laboratory studies technical properties focused on compaction and compression behaviour of tyre shreds have been investigated. In a field study of a built road, tyre shreds has been tested and evaluated, during four years, as lightweight fill and frost insulation material. Environmental properties of tyre shreds, mainly leaching characteristics, have been studied in laboratory tests and monitored in two full scale field tests.Based on the results in the laboratory studies a model is proposed for evaluation of stressstrain properties and prediction of compression behaviour. Recommendations for construction works and pavement design are suggested based on the road construction field study results.Conclusions regarding the studied leaching properties of tyre shreds, based on the laboratory tests and the field monitoring, are that zinc and iron are the metals mainly released and that the release of the studied organic compounds, i.e. PAH and phenols, are low. From an environmental point-of-view focus should be moved from PAH-compounds towards other compounds that are more interesting from mobility perspective and lack of knowledge. It is concluded from this thesis work that PAH is not a pollution problem in the area of use of tyre material covered by this work.Applications where tyre shreds have been successfully utilised as construction material, are e.g. as draining layers in landfills and as material in trotting tracks and paddocks. The utilisation of the material in trotting tracks and paddocks is especially interesting since the unique elasticity of the material is utilised. The potential of utilising tyre shreds in civil engineering construction is big. Since the available amounts of material is limited there is a possibility to direct the use of tyre shreds to the most favourable applications of tyre shreds and still solve the disposal problem of end-of-life tyres.Uttjänta däck är ett avsättningsproblem avseende de stora volymerna som produceras varje år. Däckklipp produceras främst med avseende på att reducera transportvolymen av insamlade däck. Inom EU har det införts ett förbud mot att deponera däck och däckklipp för att dels reducera den totala volymen avfall som deponeras och dels för att uppmuntra återvinning av däckmaterial. Den huvudsakliga avsättningen för uttjänta däck har fram tills nu varit energiåtervinning, främst inom cementindustrin.Däckklipp har intressanta tekniska egenskaper som fördelaktigt kan utnyttjas i anläggningstekniska tillämpningar. Karakteristiska egenskaper för däckklipp är låg densitet, hög elasticitet, låg styvhet, hög dränerande och hög värmeisolerande förmåga. Kombinationen av dessa egenskaper möjliggör tekniskt innovativa lösningar inom anläggningsbyggande.Det övergripande syftet med avhandlingen har varit att beskriva och utvärdera däckklipp som ett anläggningsmaterial ur både teknisk och miljömässig synvinkel. Arbetet har inkluderat både laboratorie- och fullskaleförsök för att utreda tekniska, miljö- och anläggningstekniska egenskaper. Vidare har det aktuella kunskapsläget om däckklipp som anläggningsmaterial utvärderats och presenterats.I laboratorieförsök har tekniska egenskaper med fokus mot packnings- och kompressionsegenskaper för däckklipp undersökts. I ett fältförsök har en vägkonstruktion med däckklipp som lättfyllnads- och tjälisoleringsmaterial byggts och utvärderats under fyra år. I laboratorieförsök har lakningsegenskaper för däckmaterial och miljöövervakningsprogram för tre olika konstruktioner utvärderats.Baserat på laboratoriestudier har en utvärderingsmodell för spännings-töjningsegenskaper och beräkning av kompression föreslagits. Rekommendationer för anläggningsteknik och vägdimensionering presenteras baserat på utvärderingen av vägkonstruktionen.Slutsatser baserat på lakningsstudierna i laboratoriemiljö och utvärderingen av miljöövervakningsprogrammen för fältkonstruktionerna är att de metaller som främst lakar ut är zink och järn och att lakningen av de studerade organiska föreningarna, d.v.s. PAH och fenoler, är låg. Från ett miljöperspektiv bör fokus flyttas från PAH mot organiska föreningar som har hög mobilitet och där kunskapsläget är lågt. Slutsatsen i detta arbete är att PAH-föreningar inte utgör ett föroreningsspridningsproblem för konstruktioner med däckklipp.Tillämpningar där däckklipp framgångsrikt har använts som konstruktionsmaterial är t.ex. i dräneringslager i deponier, i travbanor, och i paddockar. Användningen av däckklipp i travbanor och paddockar är särskilt intressant eftersom belastningen på hästarnas ligament kan minskas.Potentialen att använda däckklipp som ett anläggningsmaterial är stor. Eftersom tillgången är begränsad finns det en möjlighet att styra användningen till de lösningar där materialet används optimalt, både tekniskt och miljömässigt, och ändå avsätta all tillgänglig volym uttjänta däck.
Godkänd; 2006; 20070108 (mlk)
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Ho, Chau-man, and 何秋文. "Idealisation for mathematical modelling in geotechnical practice." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B45014280.
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Wu, Berlin. "Geotechnical design and construction automation in Taiwan." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41353.
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Wan, Richard. "Finite element implementation of some conventional geotechnical problems." Thesis, University of Ottawa (Canada), 1985. http://hdl.handle.net/10393/4576.
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Rockaway, Thomas D. "Spatial assessment of earthquake induced geotechnical hazards." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/20038.
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Kiptoo, Dennis Kipngetich. "An investigation of the effect of dynamic and static loading to geosynthetic reinforced pavements overlying a soft subgrade." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20923.
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Construction of roads over soft soils can lead to design and construction related problems linked to the soil's compressibility characteristics and low strength. Failure, in terms of bearing capacity can occur when pavements are constructed over such soft soils. When road pavements, which are constructed over soft soils, are subjected to cyclic traffic loading (dynamic in nature), rapid deterioration of the base layer material and progressive permanent deformation of the surface will occur. This not only reduces the serviceability of the pavement structure but also its design life. In this study, reinforcement geosynthetics (geogrids and geotextiles) were used as reinforcement inclusions within a granular base overlying a soft subgrade of California Bearing Ratio (CBR) less than 2% in a 1.0 m3 steel test box. Firstly, a geotextile/geogrid was placed at the interface between the base layer and subgrade. Thereafter, a combination of the geotextile at the interface (of the base and subgrade) and geogrid within the base layer. Bench scale plate load tests (static and cyclic) were conducted on a 305 mm diameter circular steel plate on the two layer system using a Universal Compression Machine. Static loading was applied at a rate of 1.2 mm/min. Dynamic sinusoidal load wave was applied with a 4 kN seating load that was linearly increased with an incremental load of 4 kN for every 8 cycles at a frequency of 0.2 Hz on a 305 mm circular plate. For both tests, settlement failure of the composite system was considered at a deformation of 75 mm as defined for unpaved roads. The results obtained from the pavement model showed that there was a significant improvement in bearing capacity and reduction in settlement accruing from geosynthetic inclusion as shown by the Bearing Capacity Ratio (BCR) of 1.21, 1.29 and 1.63 for geogrid, geotextile and geogrid-geotextile combinations respectively. Additionally, a Settlement Reduction Factor (SRF) of 18% for geogrid, 23% for geotextile and 31% for the geogrid-geotextile combination resulted. There was also an improvement in extended pavement life as depicted by the Traffic Benefit Ratio (TBR) greater than 1 for all reinforced base layers. An improved performance was realised with the double combination of geotextile at the interface, geogrid at the base.
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Bou-Mekhayel, Myriam. "Geotechnical and Geothermal Properties of Louisiana Coastal Sediments." ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2589.
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Land loss in South Louisiana is increasing at a fairly rapid rate. In an effort to reduce land loss and save the marshes of Louisiana, marsh creation projects have been proposed in carefully selected regions around the coast as part of the CPRA Coastal Master Plan 2017. Properties and characteristics of the soil obtained from soil borings were analyzed and used to determine the various design parameters that allow the marsh creation process to occur. Other properties that were taken into consideration for Louisiana coastal sediment are the geothermal properties.
This research analyses those different properties obtained from geotechnical reports from CPRA and other data bases, in order to find correlations between the different soil characteristics, specifically between the soil’s compressive strength, consolidation properties, Atterberg Limits and moisture content. Furthermore, this research also studies the geothermal properties of selected Louisiana soils and the correlation between moisture content and thermal conductivity.
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Sterianos, Benjamin. "Geotechnical properties of carbonate soils with reference to an improved engineering classification." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/9636.
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Includes bibliography.The engineering behaviour of carbonates differ substantially from quartz based soils. A review of the literature was undertaken in an attempt to identify relevant parameters which could provide the basis for an improved engineering classification. Carbonate content, cementation, crushability, particle size distribution and Atterberg limits were found to be relevant to engineering behaviour of carbonates, and should be included. The maximum obtainable void ratio (emax), which is related to the particle shape distribution, has been proposed as an additional index for carbonate sands. Results from direct shear tests showed that this parameter correlates well with crushability and compressibility. It is recommended that this parameter (emax) as determined in the test devised by Kolbuszewski (1948), should be adopted as an index property for classifying carbonate sands.
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Begaj, Qerimi Leonora. "Geotechnical centrifuge model testing for pile foundation re-use." Thesis, City, University of London, 2009. http://openaccess.city.ac.uk/17452/.
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In recent years development is at premium in many European cities. With life cycles of 25-30 years of buildings in financial cities and about 40 years in regional centres the ground is becoming more and more congested with redundant foundations. As the underground development of services and infrastructure already confines the location of building foundations, redundant foundations only add to this problem. The research described in this thesis, using centrifuge model testing, describes how the existing pile foundations in overconsolidated clay are likely to behave when their loading conditions are changed by unloading caused by demolition and subsequent reloading. This is done with the view to re-use the existing pile foundations for the new redevelopments. The influence of the new foundations on the existing foundations is also described. By re-using the foundations, the use of raw materials is reduced, the energy consummation for construction is reduced, the volume of soil from foundation construction is eliminated and the construction time significantly reduced, consequently reducing the whole costing of a structure. Experimental data was obtained from series of twenty one centrifuge model tests undertaken at 60g. The geometry of the model was such that it was possible to test two sets of foundations with each test. The performance of piles in overconsolidated clay when subjected to load/unload/reload cycles and the influence of supplementary piles used to achieve the required capacity were investigated. The model tests include comparison of the behaviour of bored piles when supplemented with mini piles of different length, number and spacing (centre to centre distance between the mini piles and the existing centre pile). An increase in capacity was observed when single piles were subjected to load cycles. It was found that this increase in capacity is dependent on the previous loading conditions of the pile. The behaviour of enhanced piles was characterised using a single pile test as datum test. The influence of these novel pile groups on the existing pile was dependent on the number, length of the mini-piles in the group and centre to centre spacing between the existing and new pile foundation.
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Zhang, Li Zhi. "Application of Bayesian model class selection on differential problems in geotechnical engineering." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2590616.
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Styler, Mark Anthony. "Investigations into the use of continuous shear wave measurements in geotechnical engineering." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50908.
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The research presented within this thesis covers the development of a means to continuously monitor shear waves in a laboratory triaxial apparatus and down-hole during seismic cone penetration. This work resulted from an investigation of ageing of Fraser River Sand using a bender element triaxial apparatus.
Shear wave propagation times from bender elements were interpreted using published time domain and frequency domain techniques. These techniques provided similar results, but the variability exceeded the effect of ageing. The frequency domain and time domain techniques had different shortcomings. The two techniques could be combined to converge on a single frequency-dependent propagation time that was independent of the trigger signal waveform. This contribution was capable of resolving the small increase in shear wave velocity with age duration.
The frequency domain component of the combined bender element technique could run continuously during an experiment. With this further contribution, it was possible to track the change in shear wave propagation time throughout an experiment. The continuous bender element testing was not observed to influence the effect of ageing.
It was found that in Fraser River Sand ageing had a small effect on the shear wave velocity, no effect on the ultimate strength, and a significant effect on the shear stiffness over the intermediate small-strain range (observed from 0.01 to 1%). The normalized shear stiffness curve shifts to larger strains and becomes more brittle with ageing.
The concepts of the developed continuous bender element method are not restricted to this equipment or even to just bender element testing. The continuous bender element method was adapted to down-hole seismic testing in the field. This contribution resulted in a continuous profile of the shear wave velocity during seismic cone penetration testing that is obtained without stopping the cone penetration.
The developments in this thesis provide a continuous measure of the shear wave velocity through a laboratory experiment and a continuous profile with down-hole penetration depth, i.e. the shear wave velocity is measured every time the other parameters are taken.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Hughes, David Bryn. "Geotechnical engineering applications in opencast coal mining : case studies from Northern England." Thesis, University of Newcastle Upon Tyne, 2003. http://hdl.handle.net/10443/858.
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Opencast coal mining using mechanical excavators has taken place in Northern England for over sixty years. In the early years the excavations for coal were relatively shallow and of limited area, typically less than 20 m deep and 50 ha in plan. Nowadays with the deployment of very large draglines and hydraulic shovels, opencast mines can be over 200 m deep and up to 1,000 ha in area. The investigations, excavations and earthworks failures associated with this activity have provided a unique opportunity to study several geotechnical engineering aspects of the drift and solid geology of Northern England, and how they impact on the mine planning, design and operations processes.
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Al-Ani, Haider Abdul Wahhab Hamdan. "Digital Geotechnical Maps and Classification of Soil Engineering Properties by Using GIS." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/367143.
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Peat is a highly organic and extremely compressible soil. The Surfers Paradise study site area (Gold Coast, Queensland, Australia, located between 27.98° and 28.01° Southing, and between 153.41° and 153.43° Easting (based on the projection of Universal Transverse Mercator UTM zone 56) has a problematic multi thickness peat layer. The peat layer ranges from 0.1 – 7.0 m at different locations and at depths between 1.1 – 40.9 m below the ground surface. To avoid the effects of the highly compressible and low shear strength peat layer, the buildings in the study area have pile foundations. The site, which lies on the beach side, has the tallest high rise buildings and skyscrapers on the Gold Coast (e.g. the Q1 Tower, Queensland’s tallest building at the time of the study); it was also considered the tallest building in Australia.
The literature review was undertaken to gain a geotechnical overview of problematic peaty soils in relation to the construction of buildings over such soils. The review was divided into three categories: (1) geology of the Gold Coast; (2) engineering properties of peat (organic layer) and its effects on the engineering design; and (3) Geographic Information System (GIS) implementation in the field of the geotechnical engineering, as well as its suitability to characterise the soil profile in the production of GIS based digital zonation maps.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Vosolo, David A. "Investigation on geotechnical engineering properties of coal mine spoil subjected to slaking." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/109789/1/David_Vosolo_Thesis.pdf.
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This research project has led to the development of a new approach to assess the saturated and unsaturated properties of soil material subjected to slaking. Constant saturation along with overburden pressure resulted in a larger vertical deformation ofInvestigation on geotechnical engineering properties of coal mine spoil subjected to slaking the slaking chambers; which is indicative of slaking, these results indicate that material slaking was occurring due to saturation and overburden pressure. This will have a substantial benefit to the mining operations with distinctive interest associated to safety of the mine spoil slopes, limiting failures to protect workers, equipment, and operational costs.
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Hamade, Tarek. "Geotechnical design of tailings dams - a stochastic analysis approach." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116869.
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Mine tailings dams are geotechnical structures that are designed to provide adequate and safe storage of tailings materials both during and after the end of mine life. The design of tailings dams is currently based on limit equilibrium methods (LEM) which are used to calculate slope stability safety factors under various operational loads. The minimum safety factor obtained from these analyses is retained to be the design safety factor. LEM's however suffer from a number of shortcomings most notably the lack of information on dam deformation and the interaction between effective stress and pore pressure. For this, advanced numerical modeling techniques accounting for the hydro-mechanical coupling occurring in the dam structure have been developed. These models provide much greater insight into the geotechnical behavior of the tailings dam. However, both LEM and numerical modeling approaches are deterministic in nature; thus, they do not take into consideration the inherent uncertainty of the construction material properties – a fact that is well known to the geotechnical engineer, yet, needs to be addressed.In this thesis, stochastic analysis approaches such as the Monte Carlo (MC) method are adopted to investigate the effect of the inherent uncertainty in material properties on the design factor of safety. Both LEM and coupled hydro-mechanical numerical models are first developed and the results for deterministic models are compiled. These are then compared with the result obtained from stochastic analyses. A case study of a new water retention tailings dam project design with well documented geotechnical data is adopted throughout the thesis study. First the LEM analysis was pursued followed by a sensitivity analysis to determine the most influential parameters on the design safety factor. Next, a fully coupled hydro-mechanical model was developed with FLAC2D in which the construction sequence was simulated in seven stages. The factor of safety (FOS) was calculated at the end of every stage using the Strength Reduction Technique (SRT). Following that, the Point Estimate Method (PEM) was then used to obtain the probability of unsatisfactory performance by considering the dam's core angle of friction, cohesion and permeability as stochastic variables. The coefficient of variation for the material properties was varied and its consequence on the probability was recorded. Next, the MC method was adopted to calculate the tailings dam's probability of unsatisfactory performance as well as its reliability. The effect of changing the probability density function (PDF) of the stochastic input parameter on the output reliability was further analyzed. Furthermore, the effect of randomness at the local level was studied using the Random Monte-Carlo (RMC) method and compared to the output of the MC method.Finally, the effect of the coefficient of correlation between the dam's core angle of friction and its cohesion on the impoundment's reliability was analyzed. This was followed by an advanced stochastic analysis using the MC method that included a third stochastic variable, the dam's core permeability. The incorporation of both mechanical and hydraulic parameters as stochastic variables lowered the impoundment's reliability; thus, highlighting the power and novelty in the hydro-mechanical stochastic analysis hybrid approach. The results of all analyses are presented in the thesis along with the findings in the conclusion.Les digues des résidus miniers sont des ouvrages géotechniques conçus pour offrir un stockage adéquat et sécuritaire des résidus et ce pendant et après la fin de la vie de la mine. La conception des digues à résidus est actuellement basée sur les méthodes d'équilibre limite (LEM) qui sont utilisés pour calculer les facteurs de sécurité de la stabilité des pentes sous diverses charges opérationnelles. Le facteur de sécurité minimal obtenu à partir de ces analyses est considéré comme facteur de sécurité de conception. Ils sont présentement utilisés dans la conception géotechnique. Cependant, LEM a des lacunes notamment le manque d'information sur la déformation d'une digue et de l'interaction entre les contraintes effectives et la pression interstitielle. Ainsi, les techniques de modélisation numérique avancées qui considèrent le couplage hydro-mécanique survenant dans la structure de la digue ont été développées. Ces modèles procurent un aperçu plus précis du comportement géotechnique de la digue à résidus. Cependant, les deux approches LEM et modélisation numérique sont déterministe. Par conséquent, ces approches ne tiennent pas compte de l'incertitude inhérente aux propriétés des matériaux de construction et ceci est un fait bien connu par l'ingénieur géotechnicien et pourtant ceci doit être abordé.Dans cette thèse, les approches d'analyse stochastiques tels que le Monte Carlo (MC) sont adoptées pour étudier l'effet de l'incertitude inhérente aux propriétés du matériau sur le coefficient de sécurité. Les deux LEM et les modèles numériques hydro- mécaniques couplés sont d'abord développés et après les résultats des modèles déterministes sont compilés. Ces derniers sont ensuite comparés aux résultats obtenus à partir des analyses stochastiques.Une étude de cas d'une nouvelle conception d'une digue à rétention d'eau à résidus avec des données géotechniques bien documentées est adoptée dans cette étude. Tout d'abord, l'analyse LEM a été poursuivi et suivi par une analyse de sensibilité pour déterminer les paramètres les plus influents sur le facteur de sécurité de la conception.Ensuite, un model couplé d'hydro-mécanique a été développé avec FLAC2D dans lequel la séquence de construction a été simulée en sept étapes. Le coefficient de sécurité (FOS) a été calculé à la fin de chaque étape en utilisant la technique de réduction de la résistance (SRT). Par la suite, la méthode d'estimation ponctuelle (PEM) a été utilisée pour obtenir la probabilité d'un rendement insatisfaisant en tenant compte de l'angle de base de la digue, de la friction, de la cohésion et de la perméabilité comme variables stochastiques. Le coefficient de variation des propriétés du matériau a été varié et ses conséquences sur la probabilité ont été enregistrées. Ensuite, la méthode de MC a été adoptée pour calculer la probabilité de rendement insatisfaisant de la digue à résidus ainsi que sa fiabilité. Par ailleurs, l'effet de la modification de la fonction de densité de probabilité (PDF) du paramètre d'entrée stochastique sur la fiabilité de sortie a encore été analysé. En outre, l'effet du hasard au niveau local a été étudiée en utilisant le hasard Monte-Carlo (RMC) et la méthode par rapport à la sortie de la méthode de MC. Enfin, l'effet du coefficient de corrélation entre l'angle de friction du noyau et la cohésion sur la fiabilité de la digue a été analysé. Ceci a été suivi d'une analyse stochastique avancé à l'aide de la méthode MC qui comprenait une troisième variable stochastique qui est la perméabilité du noyau. L'incorporation de paramètres à la fois mécaniques et hydrauliques en tant que variables stochastiques ont réduit la fiabilité de la digue, ainsi, mettant en évidence l'impact de l'analyse stochastique hydro-mécanique avec l'approche hybride. Les résultats de toutes les analyses sont présentés dans la thèse suivante ainsi que les découvertes dans la conclusion.
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Ongodia, Joan Evelyn. "Geotechnical engineering design of a tunnel support system - a case study of Karuma (600MW) hydropower project." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25498.
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Tunnels have been built since 2180 B.C., through the stone age. They became popular worldwide since the eighteenth century, as transportation, military, mining, conveyance, storage and flood control structures. Due to the increasing world population, urbanization and industrialization, the construction of underground tunnel structures are preferred as they limit interferences with existing surface uses of the land and water bodies. Although underground tunnels are a common flexible construction alternative, they are high hazard risk structures. The risks are mostly related to ground conditions. Tunnels buried at depth disturb in-situ conditions, cause ground instability and ultimately failure. Widespread tunnel failures, though not publicly advertised because of their adverse implications, have claimed human lives, cleared cities, cost 100 million United States dollars' worth in financial losses and year-long project delays. As such, stability of the structures is crucial to prevent the catastrophes thereby reducing societal outcries. Permanency of underground structures is ensured by provision of adequate resistance to any impeding failure of the ground surrounding deep underground excavations. The effectiveness of the ground-support interaction depends on geology, material properties, geotechnical parameters, loads of the surrounding ground mass and mechanism of the interaction. Using actual project information, the factors influencing stability, structural resistance as well as methods to select the required support are explored in this dissertation. The study used typical geological data of an underground tunnel component of Karuma, a proposed 600MW hydropower project in Uganda. It doubles as the largest hydropower project and first underground construction, to date. The project is located along the River Nile in a sensitive ecosystem neighboring both a major national park and the Great Rift Valley system in East Africa. The instability problem at Karuma was assessed using scientific and universal tunneling practice. Typical site data formed input for the geotechnical engineering design of the tunnel support based on analytical, observational and empirical methods. The study demonstrated that all methods were independent and dissimilar for the same geotechnical engineering challenge of the underground structure. The most comprehensive method was the one based on geotechnical engineering principles and rock mechanics theory. The outcomes of the different approaches in this study were unique functions of their underlying scientific philosophies. The study proposes that in designing adequate support systems to resist forces causing failure of underground tunnels, excavations buried in the ground should encompass several methods. The most conservative design should be chosen to ensure permanency.
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Bathe, Abhijit. "Geotechnical properties of soils using electrical measurements." Ohio : Ohio University, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1177436956.
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Nolutshungu, Lita. "A laboratory investigation on the shear strength characteristics of soil reinforced with recycled linear low-density polyethylene." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29304.
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Since the development of plastics in the 1930’s, plastics have increasingly become widely used for packaging in the commercial market place. With this application being for immediate disposal, the amount of plastic waste generated presents a challenge in the disposal thereof. The risks associated with non-biodegradable products on humans and animal life, pressure on existing landfills and the increasing costs thereof have necessitated the development of alternative options for waste management over the years. Research has resulted in various forms of treatments and recycling processes adopted and implemented as environmentally and economically viable solutions. The use of this recycled material in various applications, such as soil reinforcement addresses the need for engineering solutions with a multifaceted approach which strike a balance between environment, economy and equity. This has been the driving force behind research on the use of alternative materials in engineering design. This study aimed to present an investigation into the use of recycled Linear Low-Density (LLDPE) as reinforcement in Cape Flats sand. To understand the implication of the main aim of the investigation, a review of literature on soil reinforcement theory, various forms of reinforcement material and previous studies was conducted. The selected material for testing was in the form of pellets and flakes produced during the recycling process. Triaxial tests were done on samples where the concentration of the inclusions and compaction effort was varied. The test data presented showed that both pellets and flakes affected the shear strength by plotting Mohr’s circles and the relationship between shear stress and normal stress, which revealed changes in the shear strength parameters. The friction angle was increased by 3.35% at an optimum pellet concentration of 5%. Inclusion of the flakes, however, resulted in a maximum improvement in cohesion of 295% at 0.25% concentration. A discussion on the stress- strain relationship gave an indication on the effect on the stiffness. This showed that the peak shear stress was reached at higher strains when the flakes and pellets were included, compared to the unreinforced sand. Improvements by up to 25% were recorded from the initial 6% strain at peak shear stress of unreinforced sand. In concluding the study, Slide7.0 was used to conduct a 2D finite element analysis using Bishop’s method to analyse the practical application of LLDPE flakes and pellets for slope stability. The optimum shear strength parameters were used in the model, which resulted in an improved global factor of safety meeting the minimum requirement of 1.25.
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Sikwanda, Charles. "An Investigation of the Effects of Specimen Gripping Systems on Shear Stress at the Geosynthetic/Geosynthetic Interface in Landfill Applications." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31224.
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The use of geosynthetics has rapidly increased in nearly all geotechnical related fields as they allow for innovations, improved performance and cost effectiveness in projects. However, when geosynthetics are installed on sites, particularly on landfill slopes, their interface interaction against the adjacent materials becomes the critical section where shear failure is likely to occur. For this reason, their shear strength behaviour is determined in the laboratory at anticipated site conditions, mainly using a direct shear device to obtain design parameters. These laboratory tests are preferably conducted in accordance with ASTM-D5321 and ASTM-D6243 standards. The direct shear equipment, however, requires the use of an appropriate gripping system for shear to take place in the desired interface. Otherwise, tensile failure within the tested geosynthetics will be generated, resulting in obtaining design parameters which do not represent the actual field performance of the tested geosynthetics. This could lead to unsafe, cost ineffective, etc. design of projects with the respective geosynthetic materials. To date, many laboratories use a variety of gripping systems in a direct shear device to determine the shear design characteristics of geosynthetics and the preferred system remains a topic of concern. As a consequence, there is a large variability in the test results obtained, thus, difficulties in their interpretations. In this research, the effects of two commonly used gripping systems in a direct shear device, namely the nail plate (NP) and sandpaper (SP), have been investigated using a landfill case liner. This liner consisted of the three different classes of geosynthetics which are popularly installed in a landfill i.e. geotextile, geomembrane and geosynthetic clay liner. The results revealed that there exists a dissimilarity in the mobilized shear strength at geosynthetic interface when the NP is used as compared to the utilization of the SP due to the specimen engagement with the respective gripping systems. The exact difference, however, was not established as it varied depending on the interface tested. This highlighted the need to standardize the geosynthetic gripping systems in a direct shear device as it would capture these variations, increase result reproducibility and ease their interpretations.
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Damane, Monica. "An investigation into the volume change characteristics of loess like soil in Mount Moorosi Village in Lesotho." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31497.
Full textAbstract:
The Mount Moorosi village is situated in the Senqu River Valley of southern Lesotho, within the Stormberg landform. The integrity and aesthetic appearance of nearly all the structures in this area are undermined by recurrent cracks. At present, no apparent institutionalised effort had been conducted to investigate the source of this problem. The crack patterns were associated with the possible volume change of the underlaying loess like soil. This soil has caused a disastrous failure to brittle civil engineering structures in various parts of the world. Its behaviour is attributed to sand and silt particles bonded by minerals, which become active upon saturation and induce hydrocollapse settlement. This study characterised the volume change properties of the underlaid deposits in Mount Moorosi. The research utilised representative samples from trial pits in the study region to perform laboratory experiments such as the Atterberg limits, wet sieving, sedimentation, free swell, x-ray diffraction, scanning electron microscope and slaking. The consolidated undrained tests and hydrocollapse potential were also determined from the GEOCOMP triaxial and Global Digital System oedometer, respectively. Results revealed that Mount Moorosi is generally underlaid by a more than 3 m thickness of low plasticity (9 to 17 %) silty-sandy loess. The material had significant warping (up to 27 mm) in linear shrinkage that illustrated potential inducement of detrimental stresses to the superimposed structures during drying. The identification and quantification of the mineralogy composition clearly evidenced the passive minerals (quartz, feldspar and mica) to be predominant (86 %), while the active phases (kaolinite, carbonates, sulfates, halides, the oxides and hydroxides of aluminum and iron) were subordinate (14 %), which substantiated potential soil settlement upon wetting. Furthermore, the micrographs depicted structures that synergistically enhanced the collapse properties of the tested deposits. These included the porous clays, silts bonded by clay and silts coated with clay, which all rendered a metastable fabric. A comparison of the stressstrain graphical plots from the consolidated undrained tests at the field and saturated moisture contents indicated a drastic reduction (up to 73 %) in deviator stress at saturated water content. This was attributed to the augmentation of the interparticle spaces, caused by a rise of up to 337 kPa in pore water pressure. Shear strength parameters obtained from Mohr’s failure envelopes were also decreased by up to 80 %. The hydrocollapse index measured from the oedometer tests ranged from 10 to 15 % at a vertical stress of 200 kPa. It indicated severe settlement problems for structures constructed on this soil. This was caused by the loss in shear strength of the soil under the saturated conditions and a high slaking mechanism that reached a maximum rating of 4. Generally, the mineralogy composition, morphology, saturated shear strength, slaking and hydrocollapse index collectively indicated the possibility of soil volume decrease. In fact, the check for serviceability limit state demonstrated a settlement that exceeded the tolerable value of 50 mm. The cracks observed on structures were, therefore, related to soil settlement. This study recommends further research on suitable ground techniques to minimise settlement, thereby improving the durability of structures. Moreover, investigations should be conducted to understand the pressure induced by warping during shrinkage.
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Oriokot, Johnson Johnny Onapito. "Reinforcement of pavement subgrade using granular fill and a geosynthetic layer." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/12938.
Full textAbstract:
Includes bibliographical references.Engineers are often faced with construction of pavement structures over soft and compressible subgrade. Such conditions render the structures unable to withstand required design loads and thus are susceptible to high settlements associated with excessive distress leading to pavement damage. The use of imported quality fill to improve the load-bearing capacity of the subgrade has limited benefits, which leads to the necessity of an alternative construction approach to attain the necessary strength of the soil structure. The use of geosynthetics in soil offers a better alternative to improvement of the soil's stability. This research was conducted to determine the degree of improvement of the load-bearing capacity and reduction in settlement due to geosynthetic reinforcement of a soft clay overlain by granular material.
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Pudaruth, Yogendra. "A study on ground improvement using a combination of stone and concrete columns." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29861.
Full textAbstract:
Stone column is a cost-effective ground improvement technique that is typically employed for low-rise buildings and road embankments. This technique mainly uses naturally occurring materials as its load transferring medium. However, stone columns have some constraints because of the loose interactions between their aggregates which can lead to uncontrolled settlements, especially in soft soils. As a result, their performance is usually improved by the inclusion of geosynthetics either in layers or as a confinement. However, there was a lack of studies that used a binder within the stone column aggregates with a view to limit the bulging/lateral spreading of its aggregates in such soils. In this study, the upper portion of the stone columns was replaced by different grades of unreinforced concrete. The length of the concrete, as well as the depth of the soil beneath the columns, were varied. The effects of these different variables, when the resulting column was subjected to an applied load, were investigated. The optimum configuration of the above was identified and its resulting change in performance when it was combined with a reinforced bedding layer was studied. Considering application/installation procedures on site, it was best deemed to install and test a geosynthetic-reinforced bedding layer on top of, rather than within, the stone column. It was observed that increasing the grades of concrete did not have any consistent influence on the performance of the resulting columns when there was a considerable layer of soil beneath them. The hybrid stone columns (combination of stone and concrete) performed better than the normal stone column and even to a full concrete column of the same length in several cases. Physical modelling revealed that the bulging length ranges from 2.0-2.4D (D is the diameter of the column). Test results for the optimum hybrid stone column yielded a maximum load improvement factor of 3 to 6 folds (200% to 500% increase in bearing capacity) depending on their respective configuration compared to the unreinforced soil. The improvement factor was further increased to 9.9-fold (nearly 900% increase in bearing capacity) when the optimum hybrid stone column was tested in combination with a reinforced bedding layer. The findings from this research can be used to enhance and promote the stone column ground improvement technique while still providing an economical advantage as well.
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Noche, Ron Edward. "Scale Model Shake Table Testing of Seismic Earth Pressures in Soft Clay." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1130.
Full textAbstract:
This research consists of scale model shake table tests to investigate the development of seismic earth pressures in soft clay. The soft clay was modeled after prototype San Francisco Bay Mud consisting of a mixture of kaolinite, bentonite, class C fly ash and water. A flexible walled testing container founded on a 1g shake table was used to house the model soil and mimic 1D site response. An array of accelerometers embedded in the model soil measure during an input earthquake motion.
A scale model wall is equipped with pressure sensors to measure the seismic earth pressures over the duration of an input earthquake motion. A total of 14 time histories were run through this test set up. A single degree of freedom oscillator was added to the scale model wall and used to mimic the period of a structure. Test results show that for retaining walls with clay soils seismic earth pressures develop triangularly over the face of the wall with an amplitude of about 3.8 times the static pressures. For small building structures, the development of seismic earth pressures depends on height above the base of the wall. Although the pressure distribution is not well defined, localized peaks in pressure are observed at depths of 1/3H and 2/3H below the ground surface.
Arias intensity and cumulative absolute velocity correlate linearly with the measured dynamic pressures. Differences between arias intensity and cumulative absolute velocity for each scale model configuration are not pronounced.
The simplified Monnobe-Okabe method was also evaluated in this study. Although the Mononobe-Okabe method may be inappropriate for cohesive soils, a seismic coefficient of about 1/10 the PGA was back-calculated from empirically measured earth pressures.
The results of this investigation provides an empirical basis to the behavior of walls in clay.
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Li, Shao-Chun, and 李少群. "Application of Nanoclay in Geotechnical Engineering." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/29259517453146536855.
Full textAbstract:
碩士國立臺灣海洋大學
河海工程學系
94
This study is trying to put different contents of nano-clay into the laterite to research what’s the influence of nano-clay to the physical properties and the engineering behavior of laterite; and also try using nano-clay as a stabilizer of arenaceous trench excavation to research the stabilization of trench excavation. There’re following test results from this research: (1)The liquid limitation, plastic liquid and plasticity index of laterite are all increased gradually by adding different content (amount) of Nano-clay. The more liquid limitation, the more compression properties, and when the plasticity index increasing, it means the adsorbed water layer is more thicker and the permeability is more lower.(2)The unconfined compression strength is increased significantly when adding the Nano-clay into laterite but the unconfined compression strength wound not be increased when the content of Nano-clay from 0.5% increasing to 2%. The most unconfined compression strength could be 2.2 times better than pure laterite.(3)The coefficient of permeability is reduced gradually by adding the content (amount) of nano-clay.(4)Both the 6% of nano-clay slurry(the viscosity is 17.68 seconds) and 7% of bentonite slurry(the viscosity is 18.91 seconds) could have the stabilization of trench excavation.
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"Applications of Nanotechnology in Geotechnical Engineering." Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.40762.
Full textAbstract:
abstract: Nanotechnology has been applied to many areas such as medicine, manufacturing, catalysis, food, cosmetics, and energy since the beginning 21st century. However, the application of nanotechnology to geotechnical engineering has not received much attention. This research explored the technical benefits and the feasibility of applying nanoparticles in geotechnical engineering. Specific studies were conducted by utilizing high-pressure devices, axisymmetric drop shape analysis (ADSA), microfluidics, time-lapse technology, Atomic Force Microscopy (AFM) to develop experiments. The effects of nanoparticle on modifying interfacial tension, wettability, viscosity, sweep efficiency and surface attraction forces were investigated. The results show that nanoparticles mixed in water can significantly reduce the interfacial tension of water in CO2 in the applications of nanofluid-CO2 flow in sediments; nanoparticle stabilized foam can be applied to isolate contaminants from clean soils in groundwater/soil remediation, as well as in CO2 geological sequestration or enhanced oil/gas recovery to dramatically improve the sweep efficiency; nanoparticle coatings are capable to increase the surface adhesion force so as to capture migrating fine particles to help prevent clogging near wellbore or in granular filter in the applications of oil and gas recovery, geological CO2 sequestration, geothermal recovery, contaminant transport, groundwater flow, and stormwater management system.Dissertation/Thesis
Doctoral Dissertation Civil and Environmental Engineering 2016
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Lee, Yu-Shih, and 李煜仕. "Application of Neural Network in Geotechnical Engineering." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/32288577517032068958.
Full textAbstract:
博士國立臺灣海洋大學
河海工程學系
93
Because the usable land in Taiwan is limited, and the population grows up so fast, high-rise buildings with deep excavation and hillside inhabitation are constructed in urban and mountain areas. Deep excavation in soft soil, lateral diaphragm wall deflection is usually a major concern. Heavy rains that accompanied typhoon always cause severe debris flows and landslides. In addition, due to common occurance of earthquake, considerable amount of damages have been caused by earthquake induced liquefaction. How to make a safe design and construction and minimize damage is of utmost importance in a geotechnical engineering project. The feasibility of using artificial neural networks (ANN) for assessing geotechnical engineering problems have been examined by many researchers .The first objection of this research is to predict diaphragm wall deflection by applying the learning ability of back-propagation ANN to develop a forecast model, based on collected ten top-down cases. The results of this research indicate that ANN can reasonably predict the maguitude, as well as the location of maximum deflection of a diaphragm wall. Then a neuro-fuzzy system is developed,and the Chi-Chi earthquake data as well as other reported data are used to evaluate earthquake induced liquefaction potentials. With the help of case studies, it is shown that proposed model has less error rate than conventional empirical and traditional ANN methods. Finally, the proposed neuro-fuzzy model is used to investigate its applicability and practicalibity for debris flow. The results demonstrate that the proposed neuro-fuzzy model is applicable and effective tool for debris flow warning system.