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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

SIMPLIFIED DESIGN EQUATIONS AND LABORATORY TESTS FOR PIPE JOINTS

Wang, YU 31 January 2013 (has links)
The joint may be considered a weak point along the pipe and can have a major impact on pipe performance. However, little research has been conducted in regard to joint design. To improve current structural design criteria, this thesis presents the findings and conclusions of experimental and computational studies of the effects of longitudinal bending on joints in rigid (reinforced concrete) and flexible (corrugated steel and thermoplastic) pipes. Solutions for expected shear force, longitudinal bending moment and rotation across the joint for rigid and flexible pipes are formulated for use in structural design of pipe joints. Exact algebraic solutions for rigid pipes are derived using the beam-on-elastic-spring approximation. The formulations for flexible pipes are developed assuming that the two pipes are very long, and that the response is not affected by either the location or characteristics of those other joints. The flexible pipe design equations are developed using various closed form solutions for beams on elastic foundations developed by Hetényi (1948). Parametric studies are then presented where the key factors controlling the behaviour are examined, and the comparisons to recent experimental measurements show that the joint rotation calculated using the equations and a value of soil stiffness proposed for use in design are generally reasonable and conservative compared with the laboratory tests. To measure the capacity of the joint to accommodate the demands, a pipe joint testing frame has been designed to facilitate joint characterization experiments. Shear tests and articulation (rotation) tests have been conducted using this testing frame to examine the shear force capacity, longitudinal bending moment capacity of moment-transfer joints, and rotational characteristics of joints. The shear test results show that the joints of PVC pipe and corrugated steel pipe have similar shear stiffness while the reinforced concrete pipe joint is significantly stiffer. The results of the articulation testing indicate that the rotational capacities of the three joint systems are similar in general. Design of rotational capacity of these joints is likely dominated by considerations of assembly in the field, rather than the rotational capacity that is needed once the pipes are installed. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-01-31 15:33:41.058
2

Μαγματικά πετρώματα περιοχών Αργολίδας - Κορινθίας : ποιοτικός έλεγχος της καταλληλότητάς τους για αδρανή διαφόρων χρήσεων

Μούζουλας, Γεώργιος 03 April 2015 (has links)
Η συγκεκριμένη εργασία επικεντρώνεται στην εκτίμηση της καταλληλότητας κάποιων μαγματικών πετρωμάτων ως αδρανή υλικά για συγκεκριμένες χρήσεις και κυρίως για την κατασκευή βάσεων – υποβάσεων σε έργα οδοποιίας. Η έρευνα αφορούσε διαβασικά και δακιτικά πετρώματα από γεωϋλικά της περιοχής Μεθάνων καθώς και από την περιοχή Αγίων Θεοδώρων. Στα δείγματα αυτά αξιολογήθηκε η καταλληλότητά τους με βάση τα αποτελέσματα ποιοτικού ελέγχου που περιλάμβανε όλες τις σχετικές εργαστηριακές δοκιμές και απαιτήσεις που ορίζονται στα αντίστοιχα Ευρωπαϊκά Πρότυπα (ΕΝ), συγκεκριμένα:  Γεωμετρικές ιδιότητες (κοκκομετρική ανάλυση, δείκτης πλακοειδούς και ισοδύναμο άμμου)  Φυσικές ιδιότητες (φαινόμενη πυκνότητα και υγρασία απορρόφησης)  Μηχανικές ιδιότητες (δείκτης Micro-Deval, δείκτης LAΑV, δείκτης AIV)  Παράμετροι αντοχής βραχώδους υλικού Από τα αποτελέσματα της εργαστηριακής έρευνας διαπιστώνεται ότι τα συγκεκριμένα μαγματικά πετρώματα κρίνονται γενικά σαν «ακατάλληλα» για την κατασκευή βάσεων αλλά και υποβάσεων για οδοποιία, σύμφωνα με τις Ελληνικές και διεθνείς απαιτήσεις ποιότητας. Αυτό οφείλεται κυρίως στις αυξημένες τιμές του δείκτη LAAV που εκφράζει την αντοχή του γεωϋλικού σε μηχανική φθορά και κρούση. Εξαίρεση αποτελεί δείγμα από συγκεκριμένη θέση που χαρακτηρίζεται σαν «υψηλής ποιότητας». Επιπρόσθετα, από τις συσχετίσεις που δοκιμάστηκαν μεταξύ των επιμέρους ιδιοτήτων των γεωϋλικών διατυπώνονται εμπειρικές σχέσεις τόσο μεταξύ των μηχανικών όσο και των γεωμετρικών ιδιοτήτων. / This thesis focuses on the evaluation of the suitability of specific igneous rocks used as aggregates for uses as bases and subbases in road construction. Our research was carried out on diabasic and dacitic rocks obtained from the areas of Methana and Saint Theodore. The quality control of the tested samples were conducted under the specific guidelines of EN <European Standards>, while the procedure was refered to estimation of the following parameters:  Geometrical properties (grain size analysis, flakiness index and sand equivalent)  Physical properties (apparent density and water absorption)  Mechanical properties (Micro - Deval index, LAAV index, AIV index)  Rock material strength parameters. The laboratory testing results led to the conclusion that the samples of the geomaterial examined can be classified as "not suitable" as bases and subbases in road construction according to Greek and international specifications. The high values of the LAAV index which represent the strength of geomaterials in mechanical corrosion and crush mainly contribute to the low quality of the geomaterials. The only exception was a sample from a specific area that characterized as "high quality". Furthermore, correlations between the properties of the geomaterials were evaluated and empirical equations regarding the mechanical as well as the geometrical properties of the geomaterials were established.
3

Nature and time-scale of bed morphological adjustments towards equilibrium in meandering streams: an experimental study

BINNS, ANDREW 30 January 2012 (has links)
This thesis concerns the nature and time-scale of bed morphological adjustments towards equilibrium in alluvial meandering streams. Following the prevailing approach, the stream centrelines are assumed to follow sine-generated curves, the banks are fixed, and the flow is turbulent and sub-critical. The movable bed is flat at time t = 0; at t = Tb, the bed reaches its equilibrium or developed state. The specific objectives of this thesis are: 1) to develop a predictive equation for the bed development time Tb; 2) to determine the rate of growth of pool-bar complexes in meandering streams; and 3) to determine whether or not the large-scale, curvature-induced erosion-deposition zones of developing beds migrate upstream or downstream throughout their development. This thesis builds on the preliminary work and experimental tests by Binns (2006). The duration of bed development is found to be proportional to the square of the flow width B and inversely proportional to the channel-averaged bed-load rate (qsb)av, the proportionality factor being a function of the initial deflection angle (i.e., stream sinuosity). The form of this function is revealed on the basis of an extensive series of experimental runs carried out in meandering channels of varying values of the initial deflection angle (i.e., 20, 45, 70 and 95 degrees). In the present tests, the temporal development of the bed from time t = 0 to t = Tb was monitored by periodically stopping the flow in order to measure changes in bed surface elevation. In all runs the bed was observed to deform rapidly during the early stages of the run and slow down considerably as the bed approached equilibrium conditions. Once formed, the location of the erosion-deposition zones remained invariant in flow plan with the passage of time. Results from the runs are used to provide insight into the nature of the deformed bed in meandering streams. An expression describing the temporal rate of growth of pool-bar complexes in meandering streams of varying sinuosity is also proposed. The practical application of the equation for Tb is illustrated with available field data. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-01-26 16:43:52.424
4

Avaliação da degradação do poliestireno expandido (geofoam) por meio de ensaios de laboratório /

Carneiro Neto, Mozart Mariano. January 2019 (has links)
Orientador: Paulo César Lodi / Resumo: O poliestireno expandido (EPS), que entre vários materiais, também da origem a um gessintético, o geoexpandido, que é muito utilizado em obras geotécnicas, pois quando comparado a outros materiais, possui um menor peso específico o que diminui o peso próprio da estrutura, minimizando eventuais recalques. Além disso, a combinação de alta resistência e baixa compressibilidade o tornam uma boa escolha para obras geotécnicas. No entanto, o EPS é extremamente susceptível a solventes, hidrocarbonetos e raios ultravioletas. Nesse sentido, poucos trabalhos tem explorado os aspectos de degradação do material em aplicações geotécnicas. Assim, o presente trabalho avaliou a degradação do poliestireno expandido (EPS) por meio de ensaios laboratoriais. Para tanto, utilizaram-se amostras de EPS em cinco diferentes massas específicas, a saber: 10,0, 14,5, 18,0, 22,0 e 33,5 kg/m³. O processo de degradação das amostras foi avaliado por meio da exposição à intempérie por catorze, trinta e quarenta e cinco dias e exposição ao vapor de gasolina por sete, catorze e trinta dias. Para avaliação do processo degradativo foram realizados ensaios de absorção de água, compressão uniaxial e cisalhamento direto de interface (EPS/EPS). Os ensaios foram realizados após cada período de exposição e os resultados obtidos foram comparados aos valores de referência das amostras intactas. Os resultados mostram que os valores de absorção de água, para ambos os tipos de exposição, apresentam comportamento similar, d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Expanded polystyrene (EPS), which among many materials, also gives rise to a gessynthetic, geo-expanded, which is widely used in geotechnical works, because when compared to other materials, has a lower specific weight which decreases the structure's own weight. , minimizing any repression. In addition, the combination of high strength and low compressibility make it a good choice for geotechnical works. However, EPS is extremely susceptible to solvents, hydrocarbons and ultraviolet rays. In this sense, few studies have explored the degradation aspects of the material in geotechnical applications. Thus, the present work evaluates the degradation of expanded polystyrene (EPS) by results of laboratory tests. For this purpose, EPS samples were used in five different specific masses, namely: 10.0, 14.5, 18.0, 22.0 and 33.5 kg/m³. The degradation process of the samples was evaluated by exposure to the weather for fourteen, thirty and forty five days and exposure to gasoline vapor for seven, fourteen and thirty days. To evaluate the degradation process water absorption, uniaxial compression and (EPS/EPS) interface direct shear tests were performed. The tests were performed after each exposure period and the results obtained were compared to the reference values of the fresh samples. The main results show that the water absorption values, for both types of exposure, present similar behavior, so that the absorption is inversely proportional to the specific mass. Regarding uniaxial re... (Complete abstract click electronic access below) / Mestre
5

[en] PHYSICAL, CHEMICAL, MINERALOGICAL AND MECHANICAL PROPERTIES OF A BASALTIC RESIDUAL SOIL PROFILE FROM A CUT IN THE NORTH-SOUTH RAILWAY IN THE STATE OF TOCANTINS / [pt] PROPRIEDADES FÍSICAS, QUÍMICAS, MINERALÓGICAS E MECÂNICAS DE UM PERFIL DE SOLO RESIDUAL BASÁLTICO LOCALIZADO EM UM CORTE DA FERROVIA NORTE-SUL, NO ESTADO DE TOCANTINS

FABIO DE ALBUQUERQUE C BRANT 06 July 2005 (has links)
[pt] Embora uma vasta área do Brasil esteja localizada em regiões que a formação de basalto se faz presente, são raros os estudos em perfis contendo solo e / ou rochas de caráter básico objetivando correlacionar características químicas e mineralógicas com características geotécnicas. A área do presente estudo localiza-se em um corte em solo na Ferrovia Norte-Sul, no Município de Arguianópolis-TO, em que durante sua execução ocorreram diversos escorregamentos. O maciço de solo do corte em questão é composto em sua maior parte por solos provenientes de alteração de basalto. O presente estudo foi realizado em duas etapas. A primeira refere-se à visita ao local do corte, onde foram realizadas coletas de amostras de solo de caráter indeformado e deformado, com as respectivas descrições morfológicas dos mesmos. A segunda refere-se aos trabalhos desenvolvidos nos laboratórios de Geotecnia e Meio Ambiente do DEC da PUC-Rio, EMBRAPA SOLOS e Departamento de Geologia do Instituto de Geociências da UFRJ, abrangendo ensaios de caracterização; ensaios mineralógicos; análises químicas; obtenção das curvas características solo-água; ensaios de erodibilidade; ensaios especiais para a determinação de parâmetros de resistência e de compressibilidade. A partir dos resultados obtidos, espera-se que os mesmos proporcionem uma contribuição para o melhor entendimento de perfis intempéricos em rochas de caráter básico. / [en] In spite of the fact that basalt formations are found in several regions in Brazil, it is difficult to find investigations on the subject relating chemical and mineralogical characteristics with geotechnical ones. The site of the present study comprises a soil slope on the North-South Railroad, at Arguianópolis, Tocantins State. Several landslides occurred during the construction of the railway. The soil mass is mostly composed by soils resulting from basalt alterations. The present study was developed in two stages. The first stage comprised a visit to the site, when a morphologic description of profiles was made and undisturbed and remoulded soil samples were extracted. The second stage refers to works developed at the Geotechnical and Environmental Laboratory of PUC-Rio, at EMBRAPA Soils and at the Geology Department of the Institute of Geosciences of the UFRJ. Such works comprised soil characterization tests; mineralogical tests; chemical analyses; definition of soil-moisture characteristic curves; erodobility tests and special tests to determine strength and compressibility parameters. The results obtained provide a contribution to a better understanding of weathering profiles in rocks of basic character.
6

Avaliação dos parâmetros hematológicos e bioquímicos de cães adultos da raça Dachshund / Evaluation of hematological and biochemical parameters of Dachshund adult dogs

Backschat, Pamela Silvestre 21 December 2017 (has links)
A espécie canina foi descrita como a espécie mais polimórfica do planeta, apresentando vasta heterogeneidade interracial, mas perceptível homogeneidade intrarracial. Em considerando tal informação, a necessidade de pesquisas para constatar tais divergências, principalmente no que se diz respeito ao intervalo de referência de exames laboratoriais, vem se expandindo de maneira exponencial, com intuito de afastar qualquer interpretação equivocada e complementar no diagnóstico clínico. Portanto, a hipótese foi que de cães da raça Dachshund apresentam parâmetros hematológicos e bioquímicos diversos daqueles referenciados, na literatura, para a espécie canina. Assim, o objetivo foi determinar os parâmetros hematológicos e bioquímicos de cães adultos e sadios da raça Dachshund e compará-los aos já existentes (valores de referência) na literatura para a espécie em questão. Avaliaram-se 69 animais adultos e sadios da raça Dachshund, referentes a 23 parâmetros laboratoriais, quais sejam: contagem total de hemácias (He), hemoglobina (Hb), hematócrito (Ht), volume corpuscular médio (VCM), concentração de hemoglobina corpuscular média (CHCM), hemoglobina corpuscular média (HCM), contagem total de leucócitos, neutrófilos totais, metamielócitos, bastonetes, segmentados, linfócitos típicos, linfócitos atípicos, monócitos, eosinófilos, basófilos, plaquetas, proteína total, albumina, alanina aminotransferase (ALT), fosfatase alcalina (FA), ureia e cretinina. Após análise estatística, concluiu-se que os analitos hematócrito, hemoglobina e albumina apresentaram valores maiores quando comparados com os intervalos de referência já existentes, corroborando, assim, a heterogeneidade interracial existente e a necessidade do conhecimento de tais diferenças na rotina clínica. / The canine species was described as the most polymorphic species on the planet, presenting vast inter-racial heterogeneity, but noticeable intrarracial homogeneity. Taking this information into account, the need for research to verify such divergences, especially regarding the reference interval of laboratory exams, has been expanding exponentially, in order to avoid any misinterpretation and complementary interpretation in the clinical diagnosis. Therefore, the hypothesis was that of Dachshund dogs have hematological and biochemical parameters different from those referenced in the literature for the canine species. Thus, the objective was to finish the hematological and biochemical parameters of adult and healthy dogs of the Dachshund breed and to compare them with the existing ones (reference values) in the literature for the species in question. A total of 69 healthy adult Dachshund animals were evaluated objectifying 23 laboratory parameters: red blood cell count (Hb), hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), corpuscular hemoglobin concentration (total cholesterol), total neutrophils, metamielocytes, segmented rods, typical lymphocytes, atypical lymphocytes, monocytes, eosinophils, basophils, platelets, total protein, albumin, alanine aminotransferase (ALT), total corpuscular hemoglobin (HCMM) , alkaline phosphatase (FA), urea and creatinine. After statistical analysis, it was concluded that hematocrit, hemoglobin and albumin analytes presented higher values when purchased with the existing reference intervals, thus corroborating the interracial heterogeneity and the need for knowledge of such differences in clinical routine.
7

Faceamento de solo grampeado com malhas de aço : estudo dos critérios de dimensionamento / Soil nail facing with steel meshes : design parameters study

Rosa, Bruno Denardin da January 2015 (has links)
O uso de sistemas de faceamento flexíveis com malhas metálicas é uma alternativa viável ao uso do concreto projetado como faceamento em sistemas de solo grampeado. Vários modelos de malhas são empregados hoje para este uso, sendo classificados pela resistência à tração no sentido longitudinal. Mesmo que relevante, segundo Cala et al., (2012), somente este dado é insuficiente para o correto dimensionamento destas soluções. A presente pesquisa busca identificar quais os parâmetros de resistência são necessários para o dimensionamento de um faceamento em malha metálica. Para tanto foram avaliadas duas metodologias desenvolvidas especificamente para as malhas aplicadas junto com a solução de solo grampeado, os métodos Ruvolum e Macro1. Foram então desenvolvidos equipamentos, similares aos utilizados por Roduner (2011) e Cala et al. (2012), para caracterizar 4 diferentes modelos de malhas, avaliando a resistência das mesmas frente aos esforços considerados nos modelos de cálculo investigados, tração e o cisalhamento no contato malha/grampo. Deste modo, foram utilizados resultados de ensaios em escala real com a simulação de um talude em solo tratado com as 4 malhas, para a validação dos métodos de dimensionamento, e para investigar quais os parâmetros de resistência da malha são mais importantes. Como resultado foram determinadas as resistências das malhas avaliadas, sendo a de tração no sentido longitudinal entre 50 e 140 kN, e a resistência no contato malha/grampo, que variou entre 10 e 30 kN. Por fim foi realizada uma análise paramétrica com o método Ruvolum a fim de verificar a influência na variação da coesão, espessura instável e ângulo de atrito, dados nem sempre bem definidos em projeto. Os resultados mostram, como era esperado, a grande sensibilidade da variação nos resultados frente aos efeitos da coesão, sendo então recomendado, como em qualquer análise de estabilidade cautela no uso deste parâmetro. A análise destes resultados permite concluir que o método mais adequado para modelar um talude em solo grampeado com face em tela foi o Ruvolum, com previsões que se aproximaram das medições reais dos ensaios de campo. / The use of flexible facing systems with steel meshes is a viable alternative to the use of shotcrete as facing in soil nailing systems. Currently several different models meshes are being used today for this purpose, being classified only by the tensile strength in the longitudinal direction of the mesh. Even though this parameter is quite relevant, alone it cannot be used to design the flexible facing systems. So this research aims to identify which steel mesh strength parameters are really needed for the correct dimensioning of such solutions. In order to do so two calculation methodologies, specially developed for steel meshes design, were investigated. The design models are called Ruvolum and Macro1 Equipments were developed, similar to those presented in Cala et al. (2012), to investigate four different models of mesh, in order to find the strength parameters presented on the studied calculation models, being than tensile and shear. Thus, to validate the investigated design methodologies, field tests results were compared to the models predictions. As product of the research it was possible to determine the tensile strength of the 4 meshes models, being then ranging from 50 and 140 kN. Also it was possible to define the shear resistance in the nail head/mesh contact, which ranges from 10 to 30 kN. The last step of the research was a parametric analysis, performed with the Ruvolum method to evaluate the influence on the variation of cohesion, unstable thickness and friction angle in the predictions, since this data aren’t always available in ordinary projects. These analysis have showed that the most influent parameter is cohesion, one that is very hard to determine. Also it was found by the results analysis that the appropriate calculation model to simulate a slope stabilized with soil nail and steel meshes facing is the Ruvolum, due the closeness of the predictions to the real field data.
8

Estudo teórico e experimental da interação de paredes de alvenaria estrutural submetidas a ações verticais / Theoretical and experimental study of the interaction of structural masonry walls subjected to vertical loading

Capuzzo Neto, Valentim 05 May 2000 (has links)
No Brasil há uma crescente demanda por projetos de edifícios em alvenaria estrutural, com a progressiva elevação do número de pavimentos, impondo a necessidade de aprimoramento dos modelos de cálculo. Uma questão pouco estudada é o comportamento da interseção de paredes sob carregamento vertical, fenômeno que influencia a distribuição das ações ao longo da altura do edifício. Alguns autores admitem a transferência de forças de uma parede para outra, desde que haja o intertravamento dos blocos ao longo das interfaces das paredes. Há pelo menos duas formas de considerar a interação no dimensionamento estrutural: durante a distribuição das ações verticais ou na consideração do enrijecimento da parede. Para verificar esta interação das paredes e investigar a taxa de transferência de força foram realizados ensaios em escala real no laboratório de estruturas da EESC-USP. Realizou-se a modelagem numérica via MEF dos painéis de alvenaria ensaiados, para comparação do comportamento. Estendeu-se esta modelagem a outros painéis de alvenaria, variando-se suas dimensões, para a determinação das taxas de transferência de forças entre paredes. / In Brazil there is an increasing demand for high rise structural masonry buildings design which imposes the necessity to refine design models. One of the phenomenon on which little interest has been directed is the behaviour of wall intersections under vertical load, a phenomenon that influences the distribution of forces along the height of the building. Some authors argue that there is a transfer of forces from one wall to another in as much as there exist interlocking between the blocks along the wall interface. There are at least two ways to consider the interaction of walls in the structural design: during the distribution of the vertical load or on considering the stiffening of the wall. In order to verify the interaction of wall and thus investigate the force transfer ratio, full-scale specimens were tested at the EESC-USP laboratory. The tested panels were also modelled numerically by the FEM in order to compare with results from laboratory tests. The propose numerical model was then extended to structural masonry panels of varying dimensions in order to determine the force transfer ratio between structural masonry walls.
9

Contribution à l’étude du comportement différé des géomatériaux avec prise en compte des conditions thermo-hydriques / Contribution to the study of the time-dependent behavior of geomaterials taking into account the thermo-hydric conditions

Troupel, Hugo 15 December 2017 (has links)
La compréhension des phénomènes différés affectant le comportement mécanique des géomatériaux est essentielle pour permettre un dimensionnement plus juste des ouvrages. C'est pourquoi nous avons étudié le lien entre les différents essais permettant de caractériser les effets du temps ou de la vitesse sur le comportement mécanique des géomatériaux. Dans un premier temps, nous nous sommes attachés à caractériser l'influence du mode de sollicitation sur l'état de contrainte d'une argile en condition oedométrique. Nous avons réalisé différents types d'essais sur une argile saturée drainée : des essais à vitesse de déformation contrôlée, des essais de fluage et des essais de relaxation. D'après notre étude, il apparaît que l'état de contrainte axial et radial ne dépend pas de la vitesse de consolidation imposée, et cela, sur une large gamme de vitesses. Le chemin de contrainte en condition oedométrique est donc, au regard de nos résultats expérimentaux, à la fois une propriété de nature de l'argile et une propriété d'état du matériau. Pour étudier l'influence des facteurs environnementaux que sont la température et l'humidité relative sur le comportement mécanique de géomatériaux, nous avons développé un dispositif expérimental original permettant de contrôler la contrainte axiale, la température et l'humidité relative de l'éprouvette en condition oedométrique. Le dispositif a été testé sur un sable et sur un béton cellulaire en condition isotherme. Concernant le sable, une série d'essais oedométriques par paliers de chargement a montré que les indices de compression et de gonflement du sable ne semblent pas affectés par la température et l'humidité relative. Cependant, la température modifie le comportement hydro-mécanique du sable. En effet, à 25 °C, le chemin de contrainte et ainsi le coefficient des terres aux repos ne dépendent pas de l'humidité relative, alors qu'à 41 °C, le coefficient des terres aux repos diminue avec l'augmentation de l'humidité relative. Concernant le béton cellulaire, nous avons été contraints à travailler en condition uniaxiale, il a été montré que l'indice de compression augmente avec l'humidité relative et cela quel que soit le niveau de contrainte appliqué. Enfin, une modélisation élasto/visco-plastique a été mise en place pour rendre compte des effets de vitesse sur le comportement mécanique saturé d'un géomatériau. Après avoir discuté du rôle de chaque paramètre, nous avons identifié les paramètres permettant de reproduire l'allure des essais expérimentaux. De plus, après avoir calibré le modèle à l'aide de deux essais CRS, nous avons prédit un essai CRS à une autre vitesse de manière probante / A better understanding of deferred phenomena affecting geomaterials behaviour is essential to allow a more efficient design of structures. We studied the link between tests used to characterize deferred effects on the mechanical behavior of geomaterials. First, we focused on the influence of the stress load on the stress path of clay in oedometric condition. We carried out different types of tests on saturated drained clay: strain rate tests, creep tests and relaxation tests. Our study shows that the state of axial and radial stresses and thus the earth coefficient at rest do not depend on the strain rate imposed over a wide range of strain rates. The stress path in oedometric condition is therefore, with regard to our experimental results, both a characteristic of the clay and a property of the state of the sample. To study the influence of environmental factors such as temperature and relative humidity on the mechanical behavior of geomaterials, we developed an original experimental device to control the axial stress, temperature and relative humidity of the specimen in oedometric condition. The device was tested on sand and on cellular concrete i isothermal condition. Regarding the sand, a series of oedometer tests by loading steps showed that the index of compression and the index of swelling of the sand does not seem affected by temperature and relative humidity. However, the temperature modifies the hydro-mechanical behavior of the sand. Indeed, at 25 °C, the stress path and thus the earth coefficient at rest of soil does not depend on relative humidity, whereas at 41 °C, the earth coefficient at rest decreases with an increase in relative humidity. Concerning cellular concrete, we have been forced to work in uniaxial condition, it has been shown that the compression index increases with relative humidity regardless of the level of stress applied.Finally, an elasto/visco-plastic model has been implemented to account for time effects on the mechanical behavior of a saturated geomaterial. After discussing the role of each parameter, we have identified parameters to reproduce results of the experimental tests. In addition, after calibrating the model using two CRS tests, we predicted a CRS test at another strain rate in a convincing manner
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Εργαστηριακές δόκιμες [sic] στην περιοχή της Βάλμης Ν. Ηλείας για την αποτίμηση των γεωτεχνικών συνθηκών της εν λόγω περιοχής

Βιδάλη, Μαρία 20 October 2010 (has links)
Σκοπός της παρούσας πτυχιακής εργασίας είναι η ανάλυση, η παρουσίαση και αξιολόγηση των τεχνικογεωλογικών – γεωτεχνικών συνθηκών του οικισμού της Βάλμης του Ν. Ηλείας, σε σχέση με τις συνθήκες θεμελίωσης καθώς επίσης και με την εκδήλωση εδαφικών ασταθειών (κυρίως κατολισθήσεων). Στα πλαίσια της εργασίας και της παράλληλης Έρευνας του Εργαστηρίου Τεχνικής Γεωλογίας στην περιοχή ενδιαφέροντος πραγματοποιήθηκε μια σειρά εργαστηριακών δοκιμών Εδαφομηχανικής σε διαταραγμένα και αδιατάρακτα εδαφικά δείγματα των γεωτρήσεων. Παράλληλα, έγινε σύνταξη των γεωτεχνικών τομών των γεωτρήσεων και σχεδίαση λεπτομερών τεχνικογεωλογικών– γεωτεχνικών τομών κατά μήκος του οικισμου. Η σύνθεση των αποτελεσμάτων της γεωλογικής και γεωτεχνικής έρευνας οδήγησε στο διαχωρισμό των γεωλογικών σχηματισμών σε τρεις (3) τεχνικογεωλογικές ενότητες, με βάση την ηλικία και τη σχετική δυσκαμψία τους: (α)πρόσφατες χαλαρές αποθέσεις, (β) κροκαλοπαγή και (γ) πλειστοκαινικές αποθέσεις, οι οποίες αποτελούνται από τις υποενότητες (γ1) καστανή – καστανοκίτρινη – καστανότεφρη –τεφρή, αμμώδης ΑΡΓΙΛΟΣ με λεπτά χαλίκια και με οργανικά (CL) (CL-ML) και (γ2) κυανότεφρη – τεφροπράσινη – καστανότεφρη, ιλυώδης – ψαμμιτική ΜΑΡΓΑ (CL-ML) (ML) που αποτελεί το σεισμικό υπόβαθρο της περιοχής του οικισμού. Μετά από μία σύντομη εισαγωγή και περιγραφή του περιεχομένου της παρούσας πτυχιακής εργασίας, παρατίθενται στο Κεφάλαιο 2 τα χαρακτηριστικά της ευρύτερης περιοχής. Περιέχονται σεισμολογικά δεδομένα του σεισμού της 8ης Ιουνίου 2008, γεωγραφικά στοιχεία της περιοχής έρευνας καθώς και πληθυσμιακά δεδομένα του Δήμου Πηνείας και του οικισμού της Βάλμης, με βάση τις τελευταίες απογραφές της Ε.Σ.Υ.Ε. Περιγράφεται συνοπτικά το γεωμορφολογικό καθεστώς καθώς και οι κλιματολογικές συνθήκες της ευρύτερης περιοχής. Στην συνέχεια αναφέρεται σε γενικές γραμμές η γεωλογική δομή της ευρύτερης περιοχής, όπως επίσης και τις γεωλογικές συνθήκες και την περιγραφή των γεωλογικών σχηματισμών που δομούν την στενή περιοχή του οικισμού της Βάλμης. Ακολούθως, γίνεται αναφορά στο γενικό τεκτονικό πλαίσιο της περιοχής, με αναφορά στις τεκτονικές δομές και τη γεωδυναμική εξέλιξη της ΒΔ Πελοποννήσου και της ευρύτερης περιοχής της Βάλμης. Τέλος, γίνεται προσπάθεια για μία συνοπτική περιγραφή των υδρογεωλογικών συνθηκών, λόγω της έλλειψης υδρογεωλογικής μελέτης στην συγκεκριμένη περιοχή . Το κεφάλαιο 3 παρουσιάζει αναλυτικά τα αποτελέσματα της γεωτεχνικής έρευνας του Εργαστηρίου Τεχνικής Γεωλογίας στην περιοχή της Βάλμης. Σχολιάζονται οι εργαστηριακές δοκιμές εδαφομηχανικής που εκτελέστηκαν και τέλος παρουσιάζονται οι γεωτεχνικές τομές (Borehole Logs) όλων των γεωτρήσεων, οι οποίες περιλαμβάνουν όλη τη σχετική πληροφόρηση. Στο κεφάλαιο 4 γίνεται αναφορά στον διαχωρισμό των γεωλογικών σχηματισμών σε επιμέρους τεχνικογεωλογικές ενότητες Τέλος, στο κεφάλαιο 5 γίνεται τελική σύνθεση όλων των συμπερασμάτων που προέκυψαν από τα αποτελέσματα των εργαστηριακών δοκιμών. Στα παραρτήματα που συνοδεύουν το παρόν τεύχος παρατίθενται οι γεωτεχνικές τομές (Borehole Logs) των γεωτρήσεων, τα αποτελέσματα των εργαστηριακών δοκιμών και τέλος οι φωτογραφίες των δειγμάτων των γεωτρήσεων. / --

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