Dissertations / Theses: 'Triaxial stress'

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Walsh, Thomas George. "The triaxial vane apparatus with stress control." Thesis, University of Ottawa (Canada), 2001. http://hdl.handle.net/10393/6305.

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The scope of this research has been two fold. The first stage was to develop a Tri Vane Apparatus. The Tri Vane Apparatus uses a miniature vane incorporated into a triaxial cell in order to study the use of the vane in different soils as well as allowing the effects of different vane parameters, such as rotation rate and vane geometry, to be studied in controlled conditions. Initial research was conducted into the history of this device with special emphasis on any previous designs. The design used in the current research has incorporated many design aspects used in these previous devices but has also made several improvements. This leads into the second stage of this research. Since the development of the vane test in 1948 by Cadling and Odenstad (1948), the test has almost exclusively been used for the study of the undrained shear strength of clays. This research has investigated the use of the vane test in sands. Through the use of the Tri Vane Apparatus constructed in the first stage of this research, extensive testing has been conducted on sand, in both isotropic and anisotropic stress conditions. (Abstract shortened by UMI.)

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Ambrose, Jasmin. "Failure of anisotropic shales under triaxial stress conditions." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/19270.

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Shales are highly anisotropic in their mechanical behaviour. The strength of anisotropic shales depends not only on the magnitude of the principal stresses, but also on the bedding plane orientations relative to the principal stresses. In this study, the failure of shales are investigated using triaxial compression and extension tests, while the role of intermediate stress (sigma2) on the strength of anisotropic shale is evaluated using data from new triaxial extension tests, as well as data from the literature. Triaxial compression and extension experiments were made on two organic-rich shales, at different confining stresses and bedding angles (Beta). Examination of post-failure computed tomography (CT) and thin section images for high strength anisotropy shale show that, for large and small values of Beta, the fracture plane follows the angle that is predicted by the Coulomb’s failure criterion for an isotropic material. In the range of angles of roughly 35deg. 2 were fit more closely by the Pariseau model, whereas both shales that were a better fit with the JPW model had SAR < 2. Pariseau’s model is also more robust and accurate than Jaeger’s model when using a reduced numbers of data (i.e., data collected at fewer confining stresses and/or fewer angles). Finally, both the JPW model and Pariseau’s model was applied in the true-triaxial stress regime, in which sigma1 > sigma2 > sigma3. When analysed with Mogi’s experimental data on Chichibu Schist, both models could predict failure under true-triaxial stress conditions. Mogi’s data and the triaxial extension experiments for the two shales shows that an increase in the intermediate stress sigma2 increases the intact rock strength, whereas weak plane failure depends not only on intermediate stress sigma2, but also on bedding plane angle Beta and foliation direction (omega).

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Younessi, Sinaki Ahmad Reza. "Sand production simulation under true-triaxial stress conditions." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/1133.

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Sand production in weakly consolidated sandstone reservoirs could result in damaging the production and surface facilities. Sanding includes two stages: the failure of sandstone around the borehole and sand grains being transported into the borehole. The first stage is related to stresses around the borehole whereas the second one is controlled by drawdown pressure. In order to avoid sanding, the stresses around the borehole and the drawdown pressure which initiate sanding are studied.This research simulated sand production through laboratory experiments and numerical simulations. The effect of three independent far-field stresses was investigated which is contrary to most of the current studies being performed under a uniaxial or triaxial stress state. Accordingly, a unique experimental setup and procedure was introduced to conduct sand production experiments under true-triaxial stress conditions. The effect of drawdown pressure and state of far-field stresses on the sanding mechanism and development of the failure zone around a borehole were investigated. The experiments were conducted on 100×100×100 mm3 cubic samples of synthetic sandstones. The samples were manufactured using an established procedure developed to produce samples with properties similar to weakly consolidated sandstone. The properties of the synthetic sandstone samples were determined by conducting a series of standard rock mechanics tests on cylindrical plugs. Using a true-triaxial stress cell (TTSC), cubic samples were subjected to three independent boundary stresses and uniform lateral fluid flow from the outer boundaries. The fluid flows through the sample radially and discharges from a hole drilled at the centre of the sample: this allows the study of sanding initiation by changing the state of stress, sample material and fluid properties.In this research, firstly, the concept of sand production from a geomechanics point of view and a summary of previous sanding experiments are explained. Thereafter, the procedure to prepare a sample suitable for sand production experiments is provided. Subsequently, the experimental equipment, setup and procedure are explained in detail. This is followed by presenting the results of two sets of experiments performed at different states of stress. The effect of changing the lateral stresses on the development of the failure zone around borehole was investigated in these experiments. During these experiments it was observed that a minimum drawdown pressure is needed to initiate sand production, regardless of the state of the boundary stresses. In addition, it was observed that the geometry (i.e. width and depth) of the failure zone developed around the borehole is a function of the state of stresses.The experiments were also simulated numerically using ABAQUS in order to gain a better understanding of sand production mechanisms. The numerical modelling procedure and results are presented in a separate section in this thesis. Good agreement was obtained between the results of both experimental and numerical methods which confirm the importance of the state of stresses on the evolution of sanding. Based on the experimental and numerical observations, it was shown that the effect of the magnitude of the maximum lateral stress on the depth of failure is more significant than the minimum lateral stress.

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Millar, Michael James. "The stress-strain behaviour of jointed chalk." Thesis, University of Brighton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324397.

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Khatrush, Suleiman Ali. "The yielding of a fine sand in triaxial stress space." Thesis, University of Surrey, 1987. http://epubs.surrey.ac.uk/841582/.

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This thesis contains an experimental investigation of the yielding behaviour of sand loaded in triaxial compression, extension and a combination of both (stress reversal). The testing programme was conducted on 102 x 205 mm medium dense samples of fine Leighton Buzzard sand. A considerable part of the work was directed towards improving the testing technique in order to obtain good quality data. For this purpose, an automated stress path system was constructed and programmed utilizing a microcomputer to take full control of the applied stresses so that any desired stress path could be closely followed in the conventional triaxial cell. Furthermore, new displacement measuring devices were developed and used throughout the testing programme for monitoring both axial and radial deformation locally on the middle third of the triaxial specimen. The results indicate that generally the behaviour of sand is highly anisotropic and that during non-reversal stress paths, the yield condition can be described by a set of curved yield loci in the p' - q stress space. Such yield loci have more curvature in extension than in compression. Stress reversal is found to cause a significant softening of the stress-strain behaviour. However, depending on the level of deviatoric prestress on the opposite side, the sand may become even softer than in the virgin stress-strain condition. The typical errors likely to occur during conventional deformation measurement are discussed, and it is concluded that the use of local measurement should replace both external axial and volumetric monitoring techniques.

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Ovando, Shelley Efrain. "Stress-strain behaviour of granular soils tested in the triaxial cell." Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/7891.

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Menozzi, Jerald Paul. "Microcomputer-based controller of coupled fluid pressures in triaxial stress testing." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/104016.

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Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaf 42.
by Jerald Paul Menozzi Jr.
B.S.

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8

Salman, Talib H. "Triaxial behaviour of partially saturated granular soils at low stress levels." Thesis, University of Sheffield, 1995. http://etheses.whiterose.ac.uk/10232/.

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Granular soil is used as a backfilling material in trenches that are prepared for the installation, repair and replacement of service pipes. The soil is likely to be partially saturated and subjected to low stress levels (<100 kPa), as it exists at shallow depths (about 5m below the ground). A new double-wall triaxial cell has been designed for testing partially saturated granular specimens with height/diameter equal to 375mm/150mm, at low stress levels. The cell is able to make separate measurements and control of the pore air and pore water pressures. It was designed to make specimen stress and strain measurements internally. A conventional triaxial cell was modified to carry out tests on saturated granular specimens of the same dimensions at low stress levels. Two gradings of Limestone, fine and coarse, with maximum particle sizes of 5mm and 20mm respectively are used in the triaxial tests. The experimental results showed that the suction in the range 25 kPa to 75 kPa can have an effect on the volume, stiffness and shear strength of partially saturated granular soils at low stress levels. The results also showed that there is a linear relationship between q and (p-u_a) for the unsaturated soils or (p-u_w) for the saturated soils. And Fredlund's equation cannot be used to predict the shear strength of partially saturated granular soils at low stress levels, if the value of φ'is taken from tests carried out on saturated specimens. The results also showed that there was a relationship between q,(p-u_a), suction, specific volume and water content, all at failure.

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Al-Harthy, Said Salim. "Laboratory investigation of petrophysical properties of sandstone rocks under true triaxial stress." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/8549.

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Zissopoulos, Pantelis. "Shortcrete under triaxial stress conditions : material properties and their use in structural analysis." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/11380.

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Hoyos, Laureano R. Jr. "Experimental and computational modeling of unsaturated soil behavior under true triaxial stress states." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/32773.

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Dweirj, Mohammad Kh. "A study of stress dependent stiffness of rock using the multistage triaxial test." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434084.

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13

ALEIXO, MARCONI SOARES. "STRESS - STRAIN BEHAVIOR OF A GNEISS RESIDUAL SOIL USING THE CUBIC TRIAXIAL CELL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1526@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
O conhecimento do comportamento de solos residuais é de grande importância para projetos geotécnicos no Brasil e, em particular, na região do Rio de Janeiro, tendo em vista que o clima tropical e as características geológicas favorecem a ocorrência de mantos residuais de grande espessura. O presente trabalho trata do estudo do comportamento tensão-deformação de um solo residual proveniente de um perfil de alteração de rocha gnáissica do maciço da Tijuca, Rio de Janeiro. Como os solos residuais gnáissicos preservam as foliações herdadas da rocha matriz, investigou-se em particular a relevância de se considerar a ocorrência de anisotropia nas características de resistência e deformabilidade destes solos. No estudo foi utilizado o equipamento triaxial cúbico desenvolvido na PUC-Rio. Este equipamento possibilita o controle independente das três tensões principais, sendo mais adequado para a reprodução das trajetórias de tensões tridimensionais, usualmente associadas com obras geotécnicas no campo, e em particular, para estudos sobre as características de anisotropia de solos. O programa experimental constou de ensaios de compressão axial e hidrostática, sob condições drenadas de carregamento, utilizando o equipamento triaxial cúbico. Foram realizados também ensaios oedométricos convencionais, de modo a se obter as características de compressibilidade do solo. Foram moldados corpos de prova a partir de blocos indeformados, paralelos e perpendiculares à foliação observada no solo, o que possibilitou a análise dos resultados para direções distintas de carregamento. Para efeito de comparação sobre a relevância do arranjo estrutural dos grãos do solo, foram ensaiados também corpos de prova compactados dos mesmos materiais. A análise dos resultados permitiu a obtenção dos módulos de deformabilidade e dos parâmetros de resistência do solo residual. Em particular, foram verificados os efeitos da direção de carregamento dos corpos de prova, do nível das tensões de confinamento, do grau de intemperismo, do arranjo estrutural dos grãos e dos efeitos do grau de saturação. Pode-se concluir que os solos estudados não apresentaram efeitos marcantes de anisotropia nas características de resistência. No entanto, quanto à deformabilidade, pode-se considerar que o solo residual jovem apresentou características anisotrópicas.
The knowledge of the mechanical behaviour of residual soils is of great importance in geotechnical projects, because of its abundance in tropical regions, such as Brazil and particularly in the area of Rio de Janeiro. The present work presents a study on the fundamental stress-strain behaviour of a residual soil resulting from a profile of a gneiss rock in Rio de Janeiro. As the gneiss residual soils preservethe bedding planes from the parent rock, the relevance of considering anisotropy in the stress- strain characteristics of these soils was investigated. The cubic triaxial equipment developed at PUC-Rio was used in this research. This equipment allows the independent control of the three principal stresses, allowing the reprodution of three-dimensional stress paths, usually associated with geotechnical works in the field. The experimental program consisted of axial and hidrostatic tests, under drained loading conditions, using the cubic triaxial equipment. One- dimensional oedometer tests were also performed, in order to obtain the compressibility characteristics of the residual soil. Undisturbed specimens were prepared with the bedding planes parallel or perpendicular to the loading direction. Analysis of the test results showed the effects of load direction, confining stress level, weathering degree, structural soil fabric and saturation degree. It may be concluded that the gneiss residual soils which were selected for this research do not present significant effects of anisotropy in the strength characteristics. In the stress- strain characteristics, however, it may be concluded that the young residual soil showed effects of anisotropy.
EL conocimiento sobre el comportamiento de suelos residuales resulta de gran importancia para los proyectos geotécnicos en Brasil y, en particular, en la región de Rio de Janeiro, considerando que el clima tropical y las características geológicas favorecen la existencia de mantos residuales de gran espesor. El presente trabajo estudia el comportamiento tensión-deformación de un suelo residual proveniente de un perfil de alteración de roca gnáisica del macizo de la Tijuca, Rio de Janeiro. Como los suelos residuales gnáisicos preservan las foliaciones heredadas de la roca matriz, fue necesario estudiar si resultaba relevante considerar la aparición de anisotropía en las características de resistencia y deformabilidad de estos suelos. En el estudio se utilizó el equipo triaxial cúbico desarrollado en la PUC-Rio. Este equipo permite el control independente de las tres tensiones principales, siendo más adecuado para la reproducción de las trayectorias de tensiones tridimensionales, usualmente asociadas a obras geotécnicas en el campo, y en particular, para estudios sobre las características de anisotropía de suelos. El programa experimental incluyó ensayos de compresión axial e hidrostática, sobre condiciones drenadas de carga, utilizando el equipo triaxial cúbico. Fueron realizados también ensayos oedométricos convencionales, con el objetivo de obtener las características de compresibilidad del suelo. Fueron moldados cuerpos de prueba a partir de bloques no deformados, paralelos y perpendiculares a la foliación observada en el suelo, lo que permitió el análisis de los resultados para distintas direcciones de carga. Para efecto de comparación sobre la relevancia del arreglo extructural de los granos del suelo, se realizaron ensayos con cuerpos de prueba compactados de los mismos materiales. El análisis de los resultados permitió la obtención de los módulos de deformabilidad y de los parámetros de resistencia del suelo residual. En particular, se verificaron los efectos de la dirección de carga de los cuerpos de prueba, del nível de las tensiones de contensión, del grado de intemperización, de la disposición extructural de los granos y de los efectos del grado de saturación. Se puede concluir que los suelos estudiados no presentaran efectos marcantes de anisotropía en las características de resistencia. Sin embargo, con respecto a la deformabilidad, se puede considerar que el suelo residual joven presentó características anisotrópicas.

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Pessoa, JosÃ Rafael DiÃgenes. "Development of a triaxial cell for estimating the horizontal in stress conditions edomÃtricas." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15990.

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This thesis presents the development of a triaxial cell and a proposal for methodology for estimating horizontal tension edometric condition by conducting laboratory tests on samples unsaturated compacted soil in OMC. The development of triaxial cell permits the use of voltages or controlled deformation. Moreover, the machine allows independent application increments of axial and radial stresses, thereby facilitating implementation assay in any way triaxial stresses. The proposed methodology simplifies estimate lateral tension through comparison of axial stress-strain curves of the test edomÃtrico conventional triaxial and consolidation tests under different paths tensions with the constant relationship between the axial and radial increments. In this case, the value of K0 would be corresponding to the constant trajectory in which the triaxial test curve edomÃtrico overlaps the curve of the test in terms of stress and axial deformations. They were tests performed with different soil types and the results were- roughly consistent with estimates from correlations empirical, thus allowing validate the proposal presented in this research. also It was studied the change of horizontal stress during the collapse flood conditions in edomÃtricas. In these tests it was found that during the breakdown voltage can horizontal remain virtually constant or even decreasing.
Esta dissertaÃÃo apresenta o desenvolvimento de uma cÃlula triaxial e uma proposta de metodologia para estimativa de tensÃo horizontal em condiÃÃo edomÃtrica, atravÃs da realizaÃÃo de ensaios de laboratÃrio em amostras nÃo saturadas de solo compactadas na umidade Ãtima. O desenvolvimento da cÃlula triaxial possibilita a aplicaÃÃo de tensÃes ou deformaÃÃes controladas. AlÃm disso, o equipamento permite a aplicaÃÃo independente de incrementos de tensÃes axiais e radiais, facilitando dessa forma a execuÃÃo de ensaio triaxial sob qualquer caminho de tensÃes. A metodologia proposta simplifica a estimativa da tensÃo lateral atravÃs da comparaÃÃo das curvas tensÃo-deformaÃÃo axial entre o ensaio edomÃtrico convencional e ensaios de adensamento triaxiais sob diferentes caminhos de tensÃes com a relaÃÃo constante entre os incrementos axial e radial. Nesse caso, o valor de K0 seria o correspondente Ã trajetÃria constante na qual a curva do ensaio triaxial se sobrepÃe a curva do ensaio edomÃtrico em termos de tensÃes e deformaÃÃes axiais. Foram realizados ensaios com diferentes tipos de solo e os resultados mostraram-se aproximadamente concordantes com as estimativas realizadas a partir de correlaÃÃes empÃricas, permitindo dessa forma validar a proposta apresentada nessa pesquisa. TambÃm foi estudada a variaÃÃo da tensÃo horizontal durante o colapso por inundaÃÃo em condiÃÃes edomÃtricas. Nesses ensaios verificou-se que, durante o colapso, a tensÃo horizontal pode permanecer praticamente constante ou atÃ mesmo diminuir.

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Raybould, Matthew James. "The response of silt-clay mixtures to cyclic loading." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363244.

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LECH, RONALD SCOTT. "DETERMINATION OF CONSOLIDATED-DRAINED SHEAR STRENGTH OF UNDISTURBED LAKEBED CLAYS FROM CONSOLIDATED-UNDRAINED TRIAXIAL TESTS." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973284326.

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Al-Ajmi, Adel. "Wellbore stability analysis based on a new true-triaxial failure criterion." Doctoral thesis, Stockholm : Department of Land and Water Resources Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4037.

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Sviridov, Viacheslav [Verfasser]. "Stress-Dependent Elastic Properties of Anisotropic Sedimentary Rocks: Uniaxial and Triaxial Experiments and Theoretical Modelling / Viacheslav Sviridov." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1176638718/34.

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Mun, Byoung-Jae. "Unsaturated soil behavior under monotonic and cyclic stress states." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1361.

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The objectives of this dissertation are to measure and calculate surface free energies of soil particles, to understand the mechanical behavior of unsaturated silty sand through first studying the stress-strain relationship, the effects of matric suction and pore water chemistry and second to interpret the behavior by the critical state frame work, to develop a method to predict cone tip resistance in unsaturated soils, and to present the concept of pseudo strain and dissipated pseudo strain energy. Universal Sorption Device (USD) is developed to measure surface free energies of soil particles. The test results on a soil sample shows that specific surface area increased with decreasing particle size. The components of surface free energies and the work of adhesion increased with decreasing particle size. A servo controlled triaxial testing device is developed to test 15.24 cm in height and 7.62 cm in diameter, recompacted specimens of unsaturated soil under varying matric suction and different pore chemistry. During the test, the matric suction is maintained constant. Results from the triaxial drained tests are used for validation of the constitutive models proposed by Alonso et al. (1990). Predictions from the model are in good agreement with experimental results. The critical state model for unsaturated soil is used to calculate cone tip resistance in unsaturated silty sand. The calculated cone tip resistance is used to evaluate the liquefaction potential of unsaturated soils. The results from the stress based liquefaction potential analysis reveal that even in an unsaturated condition soil is susceptible to liquefaction. By applying the pseudo strain concept, it is possible to account for the viscous resistance of water during cyclic loading. The results of undrained cyclic triaxial tests are used to calculate pseudo-strain and dissipated pseudo strain energy. The results of calculated dissipated pseudo strain energy suggest that the effect of initial matric suction is evident. On the other hand, the effect of surface tension increase or decrease due to existence of chemical on the pore water is negligible.

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Sheahan, Thomas C. (Thomas Clair). "An experimental study of the time-dependent undrained shear behavior of resedimented clay using automated stress path triaxial equipment." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13486.

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Penketh, S. "A study into the mapping of an induced fracture in a fine grained sediment in biaxial and triaxial stress formations." Thesis, University of Salford, 2018. http://usir.salford.ac.uk/48299/.

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Unconventional hydrocarbon extraction has increased in the last twenty years due to the post-industrial west needing to increase energy security. This has meant tapping into hydrocarbon resources that are trapped within impermeable sediments. Shale hydrocarbon reservoirs have a permeability of less than 0.01mD, therefore to extract hydrocarbons the shale has to be fractured to release the trapped fluid. The ability to predict when a fracture will occur and what the resulting shape of that fracture will be has recently become increasingly important in engineering, and, in particular the petroleum industry. This has been done previously using the fracture growth equation for brittle material with additional modifications for ductile materials. A number of pseudo 3D equations have been developed which are used by these software simulations to try and predict the dimensions of a fracture so that reservoir engineers can calculate the volume of fluid expected to be produced by any drilling well. However, the simulations provide only a reasonable prediction of fluid flow and can be under or overestimated by up to 60% of returns. Previous fraccing experiments carried out to determine how the models could be improved have relied on data whereby reservoir rocks have been placed under bi-axial pressure, (two forms of pressure acting perpendicular to each other) rather than tri-axial (σ¹σ²σ³) which would more adequately reflect the pressures acting on in-situ shale formations. The present investigation has focused on building a pressure rig that allows rock samples to be placed under tri-axial pressure. To this end a concrete rig structure has been built to house three flat jacks which place a 100mm³ rock sample under pressure of up to 120 bars (12MPa) in three different directions, to represent rock at in situ depths. In conjunction with the flat jacks, 6 acoustic sensors can be placed around the rock sample to allow 3D mapping of the acoustic emissions occurring during the drilling and fracturing phase. 10 different shale samples were scanned (using the GE Phoenix v|tome|xs CT scanner) and their images reconstructed to show 3-D visualisations of any pre-existing fractures or structures. 9 of those samples were then drilled and fractured and scanned again. Using reconstruction software each drilling fracture was mapped and the dimensions measured at regular intervals in order to provide a more accurate picture of how the fracture developed when the rock is subjected to tri-axial loading. Two types of shale rock were tested, samples from the Westbury Shale Formation and samples from the Accrington Mudstone Formation. Two Accrington and one Westbury were fractured under bi-axial conditions and two Accrington and four Westbury under tri-axial pressure. The Accrington Mudstones formed a fracture that was almost elliptical in shape with ultra-thin extended tips along both the top and bottom of the fracture. There was a direct correlation between fracture width and height, those fractures that narrowed along the half-length increased in height, whilst fracture half-lengths that didn’t narrow resulted in a reduced height. The Westbury Shales, which are more organic rich, had a more distorted shape due to fractures opening up along the weaker bedding planes helping to disperse the pressure from the fracturing fluid. The acoustic sensors accurately picked up and located the fracture inducement, proving that they opened instantaneously and also revealing damage that occurred during drilling at a small distance (2mm ±1mm) below the position of the drill tip. The acoustic data also revealed existing fractures and planes of weakness that the induced fracture would follow.

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Tawana, Siyd S. "Behavior of plain and steel fiber reinforced concrete under multiaxial stress." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1178903105.

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Zhalehjoo, Negin. "Characterisation of the deformation behaviour of unbound granular materials using repeated load triaxial testing." Thesis, Federation University of Australia, 2018. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/166953.

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Unbound Granular Materials (UGMs) are used in the base/subbase layers of flexible pavements for the majority of roads around the world. The deterioration of pavements increases with the increase of traffic loadings. To ensure the long-term performance and serviceability of pavement structures through a realistic design, the precise evaluation and comprehensive characterisation of the resilient and permanent deformation behaviour of pavement materials are essential. The present PhD study aims to investigate the characterisation of the resilient and permanent deformation behaviour of four road base UGMs sourced from quarries in Victoria, Australia, using Repeated Load Triaxial (RLT) testing. The triaxial system used in this study is instrumented with four axial deformation measurement transducers to achieve highly precise measurements and to evaluate the effect of instrumentation on the resilient modulus of UGMs. The resilient Poisson’s ratio of the studied UGMs is also determined using a radial Hall-Effect transducer. Moreover, a series of permanent deformation tests is performed to precisely characterise the axial and radial permanent deformation behaviour of UGMs and investigate the factors that may significantly influence the accumulated axial and radial permanent deformations. Finally, three permanent deformation models incorporated with a time-hardening procedure are employed to predict the magnitude of permanent strain for multiple stress levels of the RLT test. The predictions using the employed models are then compared against the measured values to evaluate the suitability of the models and to identify the model that best predicts the strain accumulation behaviour of the tested UGMs. While this study focuses on the resilient and permanent deformation behaviour of four Victorian UGMs under repeated loading, the knowledge generated from this comprehensive investigation will contribute towards the global development of more reliable methods for evaluating the long-term performance of pavement structures and minimising road maintenance and repair costs.
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Salleh, Sharuddin bin Md. "Cyclic loading of carbonate sand : the behaviour of carbonate and silica sands under monotonic and various types of cyclic triaxial loading of isotropically consolidated undrained samples." Thesis, University of Bradford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338750.

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Zhang, Xuesong, and n/a. "Punching Shear Failure Analysis of Reinforced Concrete Flat Plates Using Simplified Ust Failure Criterion." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051104.153239.

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Failure criteria play a vital role in the numerical analysis of reinforced concrete structures. The current failure criteria can be classified into two types, namely the empirical and theoretical failure criteria. Empirical failure criteria normally lack reasonable theoretical backgrounds, while theoretical ones either involve too many parameters or ignore the effects of intermediate principal stress on the concrete strength. Based on the octahedral shear stress model and the concrete tensile strength under the state of triaxial and uniaxial stress, a new failure criterion, that is, the simplified unified strength theory (UST), is developed by simplifiing the five-parameter UST for the analysis of reinforced concrete structures. According to the simplified UST failure criterion, the concrete strength is influenced by the maximum and intermediate principal shear stresses together with the corresponding normal stresses. Moreover, the effect of hydrostatic pressure on the concrete strength is also taken into account. The failure criterion involves three concrete strengths, namely the uniaxial tensile and compressive strengths and the equal biaxial compressive strength. In the numerical analysis, a degenerated shell element with the layered approach is adopted for the simulation of concrete structures. In the layered approach, concrete is divided into several layers over the thickness of the elements and reinforcing steel is smeared into the corresponding number of layers of equivalent thickness. In each concrete layer, three-dimensional stresses are calculated at the integration points. For the material modelling, concrete is treated as isotropic material until cracking occurs. Cracked concrete is treated as an orthotropic material incorporating tension stiffening and the reduction of cracked shear stiffness. Meanwhile, the smeared craclc model is employed. The bending reinforcements and the stirrups are simulated using a trilinear material model. To verify the correctness of the simplified UST failure criterion, comparisons are made with concrete triaxial empirical results as well as with the Kupfer and the Ottosen failure criteria. Finally, the proposed failure criterion is used for the flexural analysis of simply supported reinforced concrete beams. Also conducted are the punching shear analyses of single- and multi-column-slab connections and of half-scale flat plate models. In view of its accuracy and capabilities, the simplified UST failure criterion may be used to analyse beam- and slab-type reinforced concrete structures.

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26

Zhang, Xuesong. "Punching Shear Failure Analysis of Reinforced Concrete Flat Plates Using Simplified Ust Failure Criterion." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/365777.

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Failure criteria play a vital role in the numerical analysis of reinforced concrete structures. The current failure criteria can be classified into two types, namely the empirical and theoretical failure criteria. Empirical failure criteria normally lack reasonable theoretical backgrounds, while theoretical ones either involve too many parameters or ignore the effects of intermediate principal stress on the concrete strength. Based on the octahedral shear stress model and the concrete tensile strength under the state of triaxial and uniaxial stress, a new failure criterion, that is, the simplified unified strength theory (UST), is developed by simplifiing the five-parameter UST for the analysis of reinforced concrete structures. According to the simplified UST failure criterion, the concrete strength is influenced by the maximum and intermediate principal shear stresses together with the corresponding normal stresses. Moreover, the effect of hydrostatic pressure on the concrete strength is also taken into account. The failure criterion involves three concrete strengths, namely the uniaxial tensile and compressive strengths and the equal biaxial compressive strength. In the numerical analysis, a degenerated shell element with the layered approach is adopted for the simulation of concrete structures. In the layered approach, concrete is divided into several layers over the thickness of the elements and reinforcing steel is smeared into the corresponding number of layers of equivalent thickness. In each concrete layer, three-dimensional stresses are calculated at the integration points. For the material modelling, concrete is treated as isotropic material until cracking occurs. Cracked concrete is treated as an orthotropic material incorporating tension stiffening and the reduction of cracked shear stiffness. Meanwhile, the smeared craclc model is employed. The bending reinforcements and the stirrups are simulated using a trilinear material model. To verify the correctness of the simplified UST failure criterion, comparisons are made with concrete triaxial empirical results as well as with the Kupfer and the Ottosen failure criteria. Finally, the proposed failure criterion is used for the flexural analysis of simply supported reinforced concrete beams. Also conducted are the punching shear analyses of single- and multi-column-slab connections and of half-scale flat plate models. In view of its accuracy and capabilities, the simplified UST failure criterion may be used to analyse beam- and slab-type reinforced concrete structures.
Thesis (Masters)
Master of Philosophy (MPhil)
School of Engineering
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27

Wyman, Richard Durtschi. "Non-Schmid Effects and Criteria for Dislocation Nucleation on Different Slip Systems at Grain Boundaries." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6423.

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Criteria for grain boundary dislocation nucleation are developed. A bicrystal containing two grain boundaries is placed under varying triaxial stress states using molecular dynamics. The local resolved shear, normal, and co-slip stresses needed for grain boundary dislocation nucleation are found. A framework is developed to detect the slip system grain boundary dislocation nucleation occurs on. A survey of the different ways grain boundary dislocation nucleation occurs in the sample shows a single grain boundary can nucleate dislocations in a rich variety of ways. Using the nucleation system and resolved stress values, criteria for grain boundary dislocation nucleation on different slip systems are developed. The proposed form of nucleation criterion suggests the activation stress has a linear dependence one the resolved shear, normal, and co-slip stresses. A residual analysis largely validates the efficacy of the proposed linear model. We show that the nucleation slip system cannot be predicted by a maximum Schmid factor analysis due to the non-Schmid resolved normal and co-slip terms. We show that a system's global pressure generally fails to predict nucleation; a local stress in the grain being nucleated into should be used. Using the nucleation criteria for each slip system, a yield surface for dislocation nucleation is built for the grain boundary used in this work.

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Marques, Sérgio Filipe Veloso. "Comportamento de uma areia artificialmente cimentada até altas tensões de confinamento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/148695.

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A busca por novas soluções técnicas que, de modo sustentável, diminuam o tempo de construção de obras de engenharia e as tornem mais econômicas, tem tomado, cada vez mais, as linhas de pesquisa do grupo de Engenharia Geotécnica da Universidade Federal do Rio Grande do Sul, onde já foram realizadas inúmeras pesquisas para estudar e compreender o comportamento de solos artificialmente cimentados. O cimento Portland é mundialmente utilizado no melhoramento da resistência e da deformabilidade dos solos, outrora impróprios para utilização. Para estudar a contribuição da cimentação para altas tensões de confinamento, foi construído um equipamento triaxial com capacidade de atingir 10 MPa de tensão confinante que permite o estudo do comportamento tensão-deformação-dilatância de solos artificialmente cimentados curados sob tensão. Juntamente, foi realizado um estudo um numa areia fina e uniforme, artificialmente cimentada, para três tempos de cura (3, 7 e 28 dias), da resistência à compressão simples (qu) e da resistência à compressão diametral (qt) em função da razão vazios/cimento (η/Civ). Os resultados mostraram que a resistência aumenta com a redução da relação vazios/cimento (η/Civ) e com o aumento do tempo de cura (t), sendo que a relação tração/compressão (qt/qu) é independente do tempo de cura e apresenta um valor médio de 0,15. Além dos resultados proferidos, outras misturas de solos granulares com diferentes tipos de cimento, variados tempos de cura, foram analisados e normalizados, obtendo-se uma curva única em que a resistência à compressão simples (qu) e a resistência à compressão diametral (qt) foram normalizadas e estão em função da relação vazios/cimento (η/Civ). Paralelamente pretendeu-se verificar qual o efeito do tipo de cura (sob tensão ou atmosférica) em misturas cimentadas com a realização de ensaios para tensões efetivas médias desde 250 kPa até 4000 kPa. Além disso, avaliou-se a variação do η/Civ e do tempo de cura para amostras curadas sob tensão. Os resultados mostram que, de um modo geral, com o aumento da tensão efetiva média, o tipo de cura não afeta os valores das tensões de desvio máximas. A parcela friccional tem uma predominância no comportamento tensão-deformação. O tipo de cura tem influência na definição da superfície de plastificação e da rigidez, verificando-se o aumento destas propriedades para amostras curadas sob tensão em relação a amostras curadas sob pressão atmosférica. Com base nos resultados obtidos nesta pesquisa, um modelo elasto-plástico com degradação da rigidez, que tem como parâmetros a resistência a compressão simples (qu), ângulo de atrito (ϕ’) e uma deformação equivalente (εs 0,7), foi proposto para simular o comportamento tensão-deformação de misturas de areias artificialmente cimentados em ensaios triaxiais, apresentando resultados satisfatórios.
The search for new technical solutions to reduce construction time of engineering works and to make them more cost-effective has been object of the research lines of the group of Geotechnical Engineering of Federal University do Rio Grande do Sul. Numerous studies have been conducted to analyse and understand the behaviour of artificially cemented. Portland cement is widely used for improving strength and deformability characteristics of soils. To study the contribution of cementation under high pressures, a 10 MPa confining pressure triaxial apparatus was built to study the stress-strain-dilatancy behaviour of artificially cemented soils cured under stress. In parallel a study was conducted on a artificially cemented uniform sand at three curing times (3, 7 and 28 days) to determine the unconfined compressive strength (qu) and splitting tensile strength (qt) according to voids/cement ratio (η/Civ) dosage methodology. The results showed that strength increases with the reduction of voids/cement ratio (η/Civ) and with the increasing of cure time (t). The tensile/compression ratio (qt/qu) is independent of curing time and presents a mean value of 0.15. In addition to these results, other granular soils mixtures with distinct types of cement and different curing times were analysed. A unique normalized curve was fit to unconfined compressive strength (qu) and splitting tensile strength (qt) against voids/cement ratio (η/Civ). At the same time, the effect of the curing type (under stress or atmospheric) was verified through triaxial compression tests with mean effective stresses ranging from 250 kPa to 4000 kPa. In addition, the variation of η/Civ and cure time was evaluated for samples cured under stress. The results show that, in general, by increasing the mean effective stress, the type of cure does not affect the values of the maximum deviatoric stress. The frictional portion is predominant in the stress-strain behavior. The type of cure affects the yielding surface and the stiffness of the samples. It was observed the increase in this properties for samples cured under stress compared to samples cured with atmospheric stress. Based on the outcomes of this study, with satisfactory results, an elastoplastic model with stiffness degradation (using unconfined compressive strength (qu), friction angle (’) and an equivalent strain (  s0.7)) was proposed to simulate the stress-strain behaviour of artificially cemented sands in triaxial tests.

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29

Kaya, Mustafa. "A Study On The Stress-strain Behavior Of Railroad Ballast Materials By Use Of Parallel Gradation Technique." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605026/index.pdf.

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The shear strength, elastic moduli and plastic strain characteristics of scaled-down ballast materials are investigated by use of the parallel gradation technique. Uniformly graded ballast materials chosen for the investigation are limestone, basalt and steel-slag. Steel-slag is a byproduct material of Eregli Iron and Steel Works, which is suitable to meet the durability test requirements as well as the electrical resistivity and the waste contaminants regulatory level. Conventional triaxial testing at a strain rate of 0.4 mm/min is used to obtain these characteristics for the scaled-down materials with a diameter of 100 mm specimen under a confining stress of 35 kPa, 70 kPa and 105 kPa
whereas that of only 35 kPa is used to characterize the accumulated plastic strain. The angle of internal friction, f, and the apparent cohesion, c, may be conservatively taken to be 42o and 35 kPa for all materials. The elastic moduli values for all materials may be predicted within an adequate estimate for the engineering purposes by using the power law parameters, K and n, determined for L-9.5 (D50 = 12.7 mm), the coarsest gradation tested for limestone. K with a reference pressure, pr = 1 kPa and n values for L-9.5, respectively, are 4365 and 0.636 for initial
8511 and 0.419 for secant
25704 and 0.430 for unloading-reloading elastic moduli. The unloading-reloading moduli increased, as the number of cycles increased. An increase in unloading-reloading modulus at N = 20 obtained was roughly 15% for scaled-down limestone
10% for the basalt
and 5% for the steel-slag. The plastic strain after first cycle, &
#949
1, and the plastic strain coefficient, C can be represented as a function of mean particle size for each material type. For the limestone, basalt and steel-slag prototype size, D50 = 45 mm, &
#949
1 values of 0.59, 0.43 and 0.75 and C values of 0.54, 1.42 and 0.74 are predicted, respectively.

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30

Oravec, Heather Ann. "Understanding Mechanical Behavior of Lunar Soils for the Study of Vehicle Mobility." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1233521118.

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31

Zeissler, Alexander. "Untersuchungen zum spannungsabhängigen Materialverhalten von Asphalt." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-167970.

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Mit dem Einzug numerischer Verfahren zur Dimensionierung von Verkehrskonstruktionen, im Speziellen für Asphaltbefestigung, werden charakteristische Materialkenngrößen benötigt. Des Weiteren wird mit der fortschreitenden Entwicklung von FEM-Programmen, die in Zusammenhang mit Strukturanalysen und Simulationsrechnungen ihren Einsatz finden, die Kenntnis detaillierter Materialkennwerte essentiell. Dass Asphalte mit ihrem charakteristischen Materialverhalten eine Temperatur- und Frequenzabhängigkeit aufweisen, ist anerkannter Stand von Wissenschaft und Technik. In Bezug auf weitere Einflussgrößen existieren nur sehr begrenzte Erkenntnisse. Im Besonderen gilt dies für Abhängigkeiten der Materialkenngrößen von aus der äußeren Beanspruchung resultierenden Spannungszuständen in der Asphaltbefestigung. Ein wesentliches Ziel der Arbeit war die Untersuchung von möglichen Spannungsabhängigkeiten der charakteristischen Materialkenngrößen von Asphalt. In diesem Zusammenhang wurden auch Fragestellungen zu anisotropen Effekten im Materialverhalten aufgegriffen. Die Untersuchungen erfolgten an zwei ausgewählten Asphaltdeckschichtmaterialien, die sich in ihrer Zusammensetzung und granularen Struktur grundlegend voneinander unterscheiden. Zum einen wurden ein Splittmastixasphalt (SMA11S mit PmB 25/55-55A) und zum anderen ein offenporiger Asphalt (PA8 mit PmB 40/100-65A) in das Versuchsprogramm aufgenommen. Die Ansprache des Materialverhaltens erfolgte versuchstechnisch mittels uniaxialer und triaxialer Versuche. Im Ergebnis der Untersuchungen zur Anisotropie von Asphaltmaterialien konnte festgestellt werden, dass die in der Regel gerichtete Verdichtung von Asphalt anisotrope Materialeigenschaften nach sich zieht, unabhängig von der Kornform der verwendeten Gesteinskörnungen und der Ausprägung der Mörtelphase. Des Weiteren war ein wesentliches Ergebnis, dass Asphaltmaterialien in weiten Bereichen der Gebrauchstemperatur ein ausgeprägtes spannungsabhängiges Materialverhalten aufweisen. Erst bei sehr tiefen Temperaturen nähert sich das Materialverhalten von Asphalt einem linear elastischen Festkörperverhalten an. Die granulare Struktur des Asphaltmaterials sowie die Ausprägung der Mörtelphase und der damit verbundenen Bindemittelfilmdicken haben maßgebenden Einfluss auf die Art und Größe der charakteristischen Materialeigenschaften sowie auf die Auswirkungen der jeweiligen Spannungsabhängigkeiten. Als Schlussfolgerung bzw. Ausblick der im Rahmen dieser Arbeit durchgeführten Untersuchungen bleibt festzuhalten, dass für die Erweiterung der Kenntnisse des grundlegenden Materialverhaltens von Asphalt weiterführende Untersuchungen speziell in Bezug auf die Eigenschaften der Einzelbestandteile sowie deren Wechselwirkungen innerhalb der Asphaltstruktur essentiell sind
Characteristic material parameters especially for asphalt pavements are required due to the introduction of numerical pavement design methods. Furthermore, the continuous development of FEM programs, which are used for structural analysis and simulation calculations, also requires the knowledge of detailed material properties. It is state of the art that asphalt shows a significant temperature and frequency dependent behavior. The knowledge regarding additional impact parameters is very limited. This is especially valid for the stress dependency of the material parameters resulting from the stress state within the asphalt pavement based on the external loads. The main aim of this work was the investigation of the possible stress dependencies of the characteristic material parameters of asphalt. In this context, questions related to the anisotropic effects of the material behavior have also been taken up. Two asphalt surface layer materials, which have significant differences in the material composition and the granular structure were investigated in this context. On the one hand a stone mastic asphalt (SMA11S with PmB 25/55-55A) and on the other hand a porous asphalt (PA8 with PmB 40/100-65A) were included in the testing scheme. Uniaxial and triaxial tests were selected to determine the material behavior at the laboratory. Within the determination of the anisotropic material behavior of asphalt, it could be proven that the usually vertical compaction direction during the compaction process effects anisotropic material properties. This behavior can be determined independent from the particle shape, the used aggregate material and the specification of the asphalt mastic. Another essential result is, that asphalt materials show a significant stress dependent material behavior in a wide range of the performance temperature. Only on very low temperatures the material behavior of asphalt can be assumed to be linear elastic. The granular structure of asphalt material as well as the specification of the asphalt mastic and the thickness of the binder between the particles have a significant influence on the type and size of the characteristic material properties and the effect of stress dependency. Finally, it can be concluded, that it is essential to investigate the material behavior of each ingredient and their interaction within the asphalt structure to expand the knowledge regarding the fundamental material behavior of asphalt

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32

Golightly, Christopher Robert. "Engineering properties of carbonate sands : the geological origins, classification, engineering, shear and triaxial stress path properties of four carbonate sands. The analysis of the transfer function for pile skin friction." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285066.

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33

Bobei, Doru Aerospace Civil &amp Mechanical Engineering Australian Defence Force Academy UNSW. "Static liquefaction of sand with a small amount of fines." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace, Civil and Mechanical Engineering, 2004. http://handle.unsw.edu.au/1959.4/38699.

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[Formulae and special characters can not be reproduced here. Please see the pdf version of the Abstract for an accurate reproduction.] The thesis provides a comprehensive study on the behaviour of sand with a small amount of fines [i.e.1/3 plastic fines and 2/3 non-plastic fines]. The work is carried out experimentally under axi-symmetric conditions using the triaxial apparatus. Conventional drained triaxial tests are conducted on isotropic consolidated specimens and all the tests indicate that sand with fines does not manifest any unusual behaviour under drained conditions. However in undrained shearing the so-called ???reverse behaviour??? is noted. The study demonstrates that the reverse behaviour conforms to the critical state framework because significant changes in the position and geometry of the critical state [CS] and isotropic consolidation [IL] lines are caused by the presence of fines. These changes cannot be adequately modelled by the intergranular void ratio as proposed by Thevanayagam and Mohan (2000). This study also demonstrates that the original state parameter [special character] as proposed by Been and Jefferies (1985) is not an adequate parameter to predict the undrained behaviour trend. A new parameter termed ???modified state parameter??? [special character] is proposed to account for the combined effects of density and confining pressure. The suitability of the modified state parameter to characterise the response of parent sand and sand with fines is assessed for a range of void ratios and confining pressures. The effect of drained stress history is an important factor affecting the subsequent undrained response. Drained pre-shearing to failure is found to improve considerably the subsequent undrained response to the extent that liquefaction may not occur. Different drained pre-shearing histories have different effects on the undrained response. However in these tests [special character] has limitations in quantifying the subsequent undrained stress-strain response. Hence, a new framework of ???yielding parameter??? [special character] extends the capability of [special character] and additional data is presented to demonstrate the suitability of this concept. The implementation of [special character] depends on whether the previous stress state reached during the stress history is below or at failure. The effects of drained pre-shearing on the position and movement of failure surface are investigated. It is found that drained pre-shearing to failure at larger confining pressures has the effect of shifting upwards part of the drained failure surface. The shift at larger stress ratios [special character] may be described in terms of dilatancy and modified state parameter at failure. The so-called strain path tests are conducted to study the influence of strain increment ratio on the deformation behaviour of sand with fines. It is found that the value of [special character] has significant effects on the stress-strain behaviour. Along negative [special character] paths the soil strain softens in the form of decreasing the shear resistance before reaching the failure state. In contrast, along positive [special character] paths the soil strain hardens to an asymptotic stress ratio. The asymptotic stress ratio decreases with increasing [special character] along a linear relationship. The framework of [special character] cannot quantify the stress-strain response along positive and negative strain paths. Consequently an ???instability parameter??? [special character] is proposed to extend the capabilities of [special character] and the reliability of this parameter is further assessed. The behaviour along a range of positive and negative [special character] paths is investigated on pre-sheared specimens. In negative [special character] the effective stress paths reach a surface located higher than the monotonic failure surface on which they trace downward towards the origin of stress space. The results indicate this surface may be the same as the drained failure envelope which has been shifted as a result of drained pre-shearing. In positive [special character] paths a large improvement is noted in both the strength and stiffness of the soil. Note The parameters [special character] and [special character] are all generalisations of [special character] so that the behaviour under complex conditions can be characterised.

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34

Champiré, Florian. "Étude expérimentale du comportement hydro-mécanique de la terre crue compactée pour la construction." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSET007/document.

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Le matériau terre peut apporter une réponse face aux problèmes que les constructions modernes rencontrent en termes d’enjeux sociétaux, économiques et écologiques. Cependant, les difficultés à comprendre et à prédire son comportement représente un obstacle au développement de cette technique dans les pays développés. Cette thèse s’insère dans un projet de recherche appelé « Primaterre » et financé par l’Agence Nationale de la Recherche française (ANR). Il vise à apporter les connaissances scientifiques nécessaires afin de pallier ce manque et aider à établir des règlementations adaptées. Ce travail s’intéresse plus particulièrement à l’impact de l’eau sur le comportement mécanique de la matrice fine du matériau, qui a un impact essentiel sur le comportement du matériau dans son ensemble. Cette matrice est constituée de sables, de limons, et d’argiles, et ce sur trois types de terres prélevées sur d’anciennes constructions en pisé. Afin de réaliser des échantillons les plus identiques et homogènes possible, un moule a tout d’abord été conçu, ce qui a permis de travailler avec des échantillons cylindriques de 3,5cm de diamètre et 7cm de hauteur. Une cellule triaxiale a été utilisée et, la seconde étape a été de concevoir les dispositifs permettant la mesure des déformations axiales et radiales, le conditionnement à température contrôlée et l’imposition d’un flux d’air humide variable de part et d’autre de l’échantillon. Différents types d’essais ont alors pu être réalisés : des essais triaxiaux à différent taux d’humidité relative ainsi que des essais de gonflement. Les paramètres mécaniques obtenus ont pu être analysés à la lumière des caractéristiques matériaux mesurées en parallèle. Enfin, l’analyse des essais de gonflement a été menée à bien à l’aide d’un modèle numérique, et ce afin de pouvoir évaluer des paramètres caractéristiques plus complexes. Ce travail de thèse se conclut par une étude supplémentaire, visant à évaluer l’impact du changement de taille d’échantillon sur les paramètres mécaniques mesurés précédemment. Ces essais ont été effectués sur des échantillons approximativement deux fois plus grands, et grâce à un dispositif expérimental plus simple, utilisant la mesure par corrélation d’images
Earthen buildings can provide an answer to face difficulties in modern constructions in both terms of sociology, economics as well as ecology. However, the difficulty to understand and to predict their behavior prevent the spreading of this technique in developed countries. This PhD is part of a research program called “Primaterre” and founded by the French National Agency for Research. It aims at providing the necessary scientific knowledge to overcome this lack and at helping the creation of appropriate standards. This work is more precisely focusing on the impact of water on the mechanical behavior of the fine proportion of the material, including sand, silt and clay, and on three different earths coming from existing rammed earth constructions. In order to be able to produce samples as identical and homogeneous as possible, a mold has first been designed, which enable to manufacture cylindrical samples with diameter of 3.5cm and height of 7cm. A triaxial cell was used and, the second step was to design different devices allowing the measurement of axial and radial deformations, the conditioning at constant temperature, and the command of a variable moist air flux at both sides of the sample. Different types of tests have thus been realized : triaxial tests at different relative humidity, as well as swelling tests. The mechanical parameters thus obtained have been analyzed in comparison with material characteristics measured in parallel. Finally, results of swelling tests have been analysed using numerical modelling, in order to assess more complex material characteristics. This thesis work ends with an additional study, aiming at evaluating the impact of scale change on the mechanical parameters previously measured. Tests have been conducted on sample approximatively twice larger, and thanks to a simpler experimental device using measurement through image correlation

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Salehian, Ali. "PREDICTING THE DYNAMIC BEHAVIOR OF COAL MINE TAILINGS USING STATE-OF-PRACTICE GEOTECHNICAL FIELD METHODS." UKnowledge, 2013. http://uknowledge.uky.edu/ce_etds/9.

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This study is focused on developing a method to predict the dynamic behavior of mine tailings dams under earthquake loading. Tailings dams are a by-product of coal mining and processing activities. Mine tailings impoundments are prone to instability and failure under seismic loading as a result of the mechanical behavior of the tailings. Due to the existence of potential seismic sources in close proximity to the coal mining regions in the United States, it is necessary to assess the post-earthquake stability of these tailings dams. To develop the aforementioned methodology, 34 cyclic triaxial tests along with vane shear tests were performed on undisturbed mine tailings specimens from two impoundments in Kentucky. Therefore, the liquefaction resistance and the residual shear strength of the specimens were measured. The laboratory cyclic strength curves for the coal mine specimens were produced, and the relationship between plasticity, density, cyclic stress ratio, and number of cycles to liquefaction were identified. The samples from the Big Branch impoundment were generally loose samples, while the Abner Fork specimens were dense samples, older and slightly cemented. The data suggest that the number of loading cycles required to initiate liquefaction in mine tailings, NL, decreases with increasing CSR and with decreasing density. This trend is similar to what is typically observed in soil. For a number of selected specimens, using the results of a series of small-strain cyclic triaxial tests, the shear modulus reduction curves and damping ratio plots were created. The data obtained from laboratory experiments were correlated to the previously recorded geotechnical field data from the two impoundments. The field parameters including the SPT blow counts (N1)60, corrected CPT cone tip resistance (qt), and shear wave velocity (vs), were correlated to the laboratory measured cyclic resistance ratio (CRR). The results indicate that in general, the higher the (N1)60 and the tip resistance (qt), the higher the CSR was. Ultimately, practitioners will be able to use these correlations along with common state-of-practice geotechnical field methods to predict cyclic resistance in fine tailings to assess the liquefaction potential and post-earthquake stability of the impoundment structures.

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Rotta, Giovani Vilnei. "Plastificação de um solo cimentado curado sob tensão." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2005. http://hdl.handle.net/10183/7729.

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A fim de avaliar a contribuição das ligações cimentantes no comportamento tensão-deformação dos solos cimentados, bem como quantificar a variação das tensões de início de plastificação e incremento de tensão de plastificação em função do índice de vazios de cura, foram realizados dezoito ensaios de compressão isotrópica em amostras artificialmente cimentadas curadas com diferentes tensões confinantes, índices de vazios e teores de cimento. As amostras foram inicialmente adensadas a várias tensões confinantes ao longo da linha de compressão normal do solo sem cimentação, simulando a formação de elementos de solos em diferentes profundidades de um depósito sedimentar cimentado. Após o adensamento, as amostras eram curadas para posterior aplicação de incrementos de tensão isotrópica. Complementarmente, dezenove ensaios triaxiais drenados foram realizados em amostras artificialmente cimentadas curadas sob diferentes tensões confinantes e índices de vazios de forma a analisar as modificações dos parâmetros de resistência, deformabilidade e plastificação em função do índice de vazios e tensão de cura. Por final, um novo modelo matemático foi proposto para simular os ensaios isotrópicos das amostras curadas com diferentes índices de vazios e teores de cura, descrevendo o comportamento teórico dos elementos de solo situados nas diferentes profundidades do depósito fictício de solo cimentado. A capacidade do modelo de simular os resultados dos ensaios isotrópicos para uma gama ampla de índice de vazios de cura e teores de cimento também foi apresentada. Comentários acerca das respostas obtidas com simulações de amostras curadas a altos e baixos índices de vazios, e solicitadas a elevadas tensões isotrópicas, também são apresentadas juntamente com uma análise dos três parâmetros adicionais requeridos pelo modelo em relação ao modelo Cam Clay: um parâmetro de medida de nível de cimentação, um parâmetro definidor do tipo de comportamento da estrutura cimentante (rígido, rígido-plástico, linear, etc.), e um parâmetro que relaciona a magnitude das tensões da estrutura cimentante com o nível de cimentação da amostra.
To evaluate the contribution of cementation on the stress-strain behaviour of cemented soils, as well as to quantify the variation of the initial yielding stress and yielding stress increment based on the curing void ration, a series of eighteen isotropic compression tests were performed en artificially cemented samples cured under different confining stresses, void ratio and cement content. The samples were initially consolidated to different stresses on the normal compression line of the non-cemented soil, in order to simulate the soil formation at different depths in cemented sedimentary deposits. After consolidated, the samples were cured and then isotropic increments of tension were applied. Complementary, nineteen drained triaxial tests were performed on artificially cemented samples cured under different confining stresses and void ratio in order to analyze the modification on the shear strength parameters, deformability and yielding based on the void ratio and curing stress. At the end, a new mathematical model was proposed to simulate the isotropical tests performed on samples cured with different void ratio and cement content, describing the theorical behavior of the soil elements situated on different depths of a fictitious deposit of cement soil. The model’s ability to simulate the results of the isotropic tests performed for a wide range of curing void ratio and cement was also presented. Comments about the simulations of samples cured with low and high void ratios and consolidated to high isotropic stresses are also presented together with an analysis of the three additional parameters required by the model in relation to Cam Clay model: a parameter measuring the cementation level, a parameter defining the kind of cementing structure behaviour (rigid, rigid-plastic, linear, etc.) and a parameter that relates the stress magnitude of the cementing structure with the cementation level of the sample.

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37

Kido, Ryunosuke. "Microscopic Characteristics of Partially Saturated Soil and their Link to Macroscopic Responses." Kyoto University, 2019. http://hdl.handle.net/2433/242476.

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Moulin, Gérard. "Etat limite d'une argile naturelle : l'argile de pornic." Nantes, 1988. http://www.theses.fr/1988NANT2028.

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Description d'une naturelle, l'argile de pornic, suivant les concepts d'etat limite et d'etat critique. On realise une serie d'essais triaxiaux axisymetriques sur argile consolidee et on met en evidence la courbe d'etat limite du materiau, intersection de la surface d'etat limite et de la surface dite "d'etat surconsolide". La representation des chemins contraintes-deformations dans un diagramme original ou dans le diagramme normalise permet de cartacteriser leur reciprocite et de suivre leur evolution au passage de la courbe d'etat limite. L'etude de l'influence du temps ou de la vitesse de deformation demontre que les enveloppes de fluage se contractent dans l'espace des contraibntes quand le temps augmente et qu'une unique fait defaut pour caracteriser reciproquement les chemins de contraintes draines et non-draines en fonction des vitesses de sollicitations

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39

Colliat-Dangus, Jean-Louis. "Comportement des matériaux granulaires sous fortes contraintes : influence de la nature minéralogique du matériau étudié." Grenoble 1, 1986. http://www.theses.fr/1986GRE10032.

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Etude essentiellement experimentale, comportant, apres un bilan des etudes deja realisees, une etude preliminaire de l'influence des conditions experimentales sur le comportement d'un sable dans un essai triaxial de compression (role de l'antifrottage de et de l'elancement de l'echantillon); ensuite une etude du comportement d'un materiau classique (sable quartzitique de carriere) et d'un materiau a porosite intragranulaire (sable calcaire provenant d'un site petrolier marin). Ebauche aussi d'une approche microstructurale. Le niveau de contrainte envisage (superieur a 10 mpa) peut etre developpe en pointe des pieux battus

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Kostiha, Vojtěch. "Zesilování železobetonových sloupů ovinutím FRP tkaninou." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390261.

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The doctoral thesis deals with the strengthening of reinforced concrete columns by FRP fabric wrapping. Its aim is to describe the principles of confinement based on the analytical study, numerical simulations and the results of the experimental program. The description of the confinement philosophy is made with respect to the type of FRP material used. It was therefore possible to present a design process of confinement, which accurately predicts the behaviour of the confined columns. At the same time, some effects limiting the effect of confinement (e.g. the method of wrapping, the number of FRP fabric layers, the slenderness of the element, etc.) are included in the design. The dissertation also presents basic information about FRP material and its properties and gives an overview of design approaches of the FRP confined columns. The dissertation also pointing out the shortcomings of the design code ČSN EN 1992-1-1. The stated example highlights the significant variation in properties of confined concrete determined by selected approaches. This variation of properties complicates the design of this strengthening method. The experimental program was used to verify the basic principles of confinement and, through high columns, allowed a description of the behaviour in almost the whole range of interaction diagram. The conclusions of the work provide information on possible future research direction.

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Dareeju, Biyanvilage. "Performance evaluation of unsaturated rail track foundations under cyclic moving wheel load." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/102697/4/Biyanvilage%2520Sampath%2520Sri%2520Sameera_Dareeju_Thesis.pdf.

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This thesis developed an alternative laboratory element testing method to evaluate the response of the unsaturated soils of rail track foundations under repeated moving wheel loadings. The novel laboratory testing method is more capable of producing the realistic strength-deformation characteristics of the unsaturated soils with the effects of principal stress axis rotation (PSAR), which can be used to redesign the conservative rail track guidelines.

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Dalla, Rosa Francisco. "Comportamento mecânico de um solo cimentado curado sob tensão em ensaios triaxiais." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/8685.

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O comportamento de solos estruturados por cimentação é fortemente influenciado pelo estado de tensões existente durante a deposição do agente cimentante. Procedimentos rotineiros de extração e preparação de amostras em laboratório geralmente causam danos à estrutura natural do material, impedindo, muitas vezes a observação do comportamento real do ponto de vista de rigidez e de deformabilidade. A simulação, em laboratório, das condições de confinamento durante a formação da estrutura cimentante, torna-se uma condição necessária para o estudo do comportamento desses materiais. Seguindo essa linha, o trabalho busca avaliar a influência da tensão de confinamento (tensão de cura) existente durante a formação da cimentação no comportamento deste material, a partir de ensaios triaxiais drenados consolidados isotropicamente. Assim, neste estudo propõe-se a utilização de um solo artificialmente curado sob tensão, observando em conjunto a essa variável a influência do nível de cimentação bem como os efeitos oriundos da tensão confinantes utilizada na fase de cisalhamento. Procurou-se avaliar características de deformabilidade e resistência, através de uma análise do comportamento dos materiais. A avaliação das superfícies de plastificação foi realizada a partir da análise de pequenas deformações do solo cimentado. A análise tensãodilatância se desenvolveu com base no exame do comportamento do material a deformações relativamente grandes. Os resultados mostraram, no geral, que o comportamento do material cimentado foi fortemente influenciado pela variação da tensão de cura, tanto a pequenas bem como a deformações relativamente grandes.
The behavior of cemented structured soils is strongly influenced by the existing stress state during the addition of the cementation agent. The common procedures for laboratory sampling usually cause damage to the natural structure of the materials, hindering, many times, the identification of the real behavior in regard to deformability and stiffness properties. The simulation, in laboratory environment, of confining conditions during the cement structure formation turns to be a mandatory circumstance for the study of the material’s behavior. Inside this context, this work aims to evaluate the influence of the existing confining stress (stress cure) during the cement formation in the behavior of the material, through isotropic drained triaxial tests. Thus, it suggested in this study the usage of artificially cemented soil cured under stress, with parallel observation of the influence of the cement degree, as well the effects from the confining stress used during the shearing stage. It was also evaluated deformability and strength characteristics through behavior analyses of the materials. An assessment of the yield surfaces was carried on from soil cemented small deformation analysis. The evaluation of stress-dilatancy was developed based on the exam of relatively large deformation behavior. The results showed that the general behavior of this material was strongly influenced by the variation of the stress curing both at small strains and at relatively large strains.

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Tounsi, Hafssa. "Modélisation THMC de la congélation artificielle des terrains : Application à la mine de Cigar Lake." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM053.

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La congélation artificielle des terrains est utilisée depuis des décennies comme technique de stabilisation et d’imperméabilisation temporaires des terrains pour résoudre des problèmes de génie civil ou minier à moindres coûts. Réussir sa mise en oeuvre nécessite l’utilisation d’outils numériques permettant de prédire l’évolution des parties congelées et la stabilité des terrains. Cette thèse propose une approche de modélisation, élaborée suivant une démarche thermodynamiquement cohérente couplant la thermique, l’hydraulique, la mécanique et la salinité, permettant de simuler la congélation des terrains. Elle inclue un modèle de comportement élasto-viscoplastique, basé sur des essais de laboratoire, capable de prédire la réponse d’un sol congelé. Un nouveau dispositif pour la réalisation d’essais triaxiaux à température et à vitesse de déformation contrôlées a été mis en place à cet effet. Le modèle thermo-hydro-mécanique et chimique a été validé par des essais de gel sur des éprouvettes initialement saturées avec de l’eau pure ou avec une solution de chlorure de sodium à diverses concentrations. A l’échelle de la structure, il a été appliqué au cas de la mine de CigarLake (Canada), à travers des simulations thermo-hydro-mécaniques couplées, qui ont permis de prédire l’évolution de la congélation dans le terrain et d’évaluer son impact sur les déplacements autour des tunnels de production excavés en dessous du massif congelé
Artifical ground freezing (AGF) has been used for decades as a temporary soil stabilisation and waterproofing technique inorder to solve civil or mining engineering problems at lower costs. A successful implementation of this technique requires the use of numerical tools to predict the freezing evolution and the site stability. Through a thermodynamically consistent framework, a fully coupled thermo-hydro-mechanical formalism, considering the salinity effect and capturing the most relevant phenomena of ground freezing, is derived. The formalism includes an elasto-viscoplastic constitutive model, able to correctly reproduce the mechanical behavior of frozen soil, and fitted against temperature and strain rate-controlled triaxial tests carried out using a newly-developed experimental facility. The proposed approach is validated by meansof freezing laboratory tests, carried out on specimens initially fully saturated with pure water or with sodium chloride solutions at various concentrations. At the field scale, the formalism is applied to the case of the Cigar Lake mine. Fully coupled thermo-hydro-mechanical simulations of the ground freezing and excavation activities taking place in the mine are performed, in order to predict the freezing evolution in the ground and its influence on the ground movements in the vicinity of production tunnels excavated below the frozen ground

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Dalla, Rosa Francisco. "Efeito do estado de tensões de cura no comportamento de uma areia artificialmente cimentada." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/32004.

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O estudo em laboratório do desempenho mecânico de solos artificialmente cimentados está normalmente vinculado à simulação do comportamento de geomateriais naturalmente formados em campo. Por outro lado, o estudo desses novos materiais pode ser também ferramenta útil na previsão do comportamento de aterros de solos artificialmente melhorados. O comportamento de solos cimentados possui considerável influência da densidade e do estado de tensões a que estes materiais estão submetidos durante a fase que compreende a cimentação dessas partículas. Uma alternativa ao estudo da cimentação nestes solos, é a elaboração de um meio em que as amostras possam ser cimentadas sob um estado de tensões específico, e que ao mesmo tempo em que se promove uma redução do índice de vazios do respectivo material. Seguindo nessa analogia, o presente estudo visa apresentar resultados de ensaios triaxiais realizados em amostras de um solo artificialmente cimentado, curadas sob diferentes níveis de tensão e estado de tensões. São abordados os resultados do ponto de vista da rigidez e deformabilidade encontrados para o material. Os resultados demonstraram que a alteração dos estados de tensões de cura, bem como a magnitude das tensões confinantes durante a cura, apresentaram influência no comportamento tensão-deformação-dilatância das amostras artificialmente cimentadas.
The laboratory study of mechanical performance of artificially cemented soils is normally associated with the mechanical behaviour of geomaterials that were created in field. The behaviour of artificially cemented soils has substantial influence of density and the stress state that these materials have been submitted during the particles cementation. Thus, an alternative to the understanding of cement effects in these soils is the preparation of a similar environment where the specimens can be submitted the cementation while a specific stress state is applied, promoting the respective void ratio reduction. Following this approach, this study aims to show the results of triaxial tests carried out in an artificially cemented soil, which was cured at different stress states. The results have shown that the changing of stress state of curing, as well as the intensity of the confining stress during the cure, presented considerably influence in the stress-strain-dilatancy of the artificially cemented samples.

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45

Baumgarten, Lars. "Gesteinsmechanische Versuche und petrophysikalische Untersuchungen – Laborergebnisse und numerische Simulationen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-202612.

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Dreiaxiale Druckprüfungen können als Einstufenversuche, als Mehrstufenversuche oder als Versuche mit kontinuierlichen Bruchzuständen ausgeführt werden. Bei der Anwendung der Mehrstufentechnik ergeben sich insbesondere Fragestellungen hinsichtlich der richtigen Wahl des Umschaltpunktes und des optimalen Verlaufs des Spannungspfades zwischen den einzelnen Versuchsstufen. Fraglich beim Versuch mit kontinuierlichen Bruchzuständen bleibt, ob im Versuchsverlauf tatsächlich Spannungszustände erfasst werden, welche die Höchstfestigkeit des untersuchten Materials repräsentieren. Die Dissertation greift diese Fragestellungen auf, ermöglicht den Einstieg in die beschriebene Thematik und schafft die Voraussetzungen, die zur Lösung der aufgeführten Problemstellungen notwendig sind. Auf der Grundlage einer umfangreichen Datenbasis gesteinsmechanischer und petrophysikalischer Kennwerte wurde ein numerisches Modell entwickelt, welches das Spannungs-Verformungs-, Festigkeits- und Bruchverhalten eines Sandsteins im direkten Zug- und im einaxialen Druckversuch sowie in dreiaxialen Druckprüfungen zufriedenstellend wiedergibt. Das Festigkeitsverhalten des entwickelten Modells wurde in Mehrstufentests mit unterschiedlichen Spannungspfaden analysiert und mit den entsprechenden Laborbefunden verglichen.

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Chen, Chih-Wei, and 陳智偉. "Development of a Triaxial Stress Sensor." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/79615078448273225344.

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Dong, Zuo-Chun, and 董作群. "Using digital image correlation in triaxial stress sensor." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/11275044670372839084.

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碩士
國立交通大學
機械工程系所
104
The present study aims to using DIC(Digital Image Correlation) in the development of a triaxial stress sensor system.The sensor can measure normal and shear stress at the same time. Toward this end, a standard operating procedure for manufacturing a novel triaxial stress sensor has been established. The sensor system includes a flexible and transparent material(PDMS), a series of image sensors as well as a data acquisition and processing system. Therefore, when the material deforms with external load, using image sensors and DIC algorithm to calculate the displacement of the material from the images. The stress-displacement relationship of the PDMS material, obtained by means of calibration experiments and numerical simulations, can then be incorporated to recover the normal and shear stress.In this thesis, according to normal and shear and both force, present recover result with overall system. the results will compare with numerical simulations.

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Tolle, Michael C. "Ductile facture of metals under high triaxial stress states." Thesis, 1994. http://hdl.handle.net/1957/35695.

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Tu, Ming-Tsung, and 杜明璁. "Triaxial Stress Wave Tests on Isotropic Compressed Saturated Soils." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/44716176994004742738.

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碩士
淡江大學
土木工程學系
88
The objective of this study is to understand the effects of the factors that include the height of specimens, the shape of the soil particles, effective cell pressure, initial relative density, the frequency of the waves, percentage of clayey finers and the ways of the load applied on the shear wave velocities of saturated soils under isotropic compression. The tests are conducted by the triaxial stress wave instrument at the Department of Harbor and River Engineering of NTOU which is similar to those suggested by Hsu(1997) and Hsu(1999). By comparing the test results, the height of the specimen is found not affecting the shear wave velocities. The wave velocities will increase with the increase of the initial relative density, and they will increase with the increase of the effective cell pressure significantly. The wave velocities of rounded soils are found higher than the subangular soils. For quartz sand, the optimum frequency to measure the shear wave velocities is from 10 to15 kHz. Adding bits of clay(<10%) into quartz sand will increase the shear wave velocities(<7%). The ways of loading applied does not influence the material shear wave velocities very much.

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Jan, Fuh-Jye, and 詹富傑. "Preliminary Development and Analyses of "Stress-Wave Triaxial Testing Apparatus"." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/55409819980009023131.

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Dissertations / Theses on the topic 'Triaxial stress'

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