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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.
11

Slope Stability Assessment Along The Bursa-inegol-bozuyuk Road At Km: 72+000-72+200

Oztepe, Damla Gaye 01 September 2009 (has links) (PDF)
The purpose of this study is to determine the most suitable remediation technique via geotechnical assessment of the landslide that occurred during the construction of Bursa-ineg&ouml / l-Boz&uuml / y&uuml / k Road at KM: 72+000-72+200 in an ancient landslide area. For this purpose, the geotechnical parameters of the mobilized soil along the slide surface was determined by back analyses of the landslide at four profiles by utilizing the Slope/W software. The landslide was then modeled using coupled analyses (with the Seep/W and Slope/W softwares) along the most representative profile of the study area by considering the landslide mechanism, the parameters determined from the geotechnical investigations, the size of the landslide and the location of the slip circle. In addition, since the study area is located in a second degree earthquake hazard region, pseudo-static stability analyses using the Slope/W software were performed incorporating the earthquake potential. The most suitable slope remediation technique was determined to be a combination of surface and subsurface drainage, application of rock buttress at the toe of the slide and unloading of the landslide material. A static and dynamic analyses of the landslide was also performed through utilizing finite element analyses. The static analyses were calibrated using the inclinometer readings in the field. After obtaining a good agreement with the inclinometer readings and finite element analyses results, the dynamic analyses were performed using acceleration time histories, which were determined considering the seismic characteristics of the study area.
12

Análise de ruptura de talude em solo não saturado / Slope back analysis in unsatured soils

José Antonio Cancino Calle 30 June 2000 (has links)
Apresenta-se neste trabalho uma análise de ruptura de um talude em solo não saturado. O talude, com cerca de 15 m de altura, é composto de areia fina a média argilosa, com grau de saturação da ordem de 55% e SPT variando entre 4 golpes no topo a 13 golpes na base. Determinaram-se as seguintes propriedades do solo: resistência, condutividade hidráulica saturada e não saturada e curva de retenção, além de medir-se a sucção matricial em campo ao longo do ano. Efetuaram-se análises paramétricas para avaliar o efeito da precipitação na mudança do perfil de sucção matricial do terreno e suas implicações na resistência e, por extensão, na estabilidade do talude. Construíram-se, também, ábacos que incluem o efeito da variação da sucção matricial, utilizáveis para taludes com características semelhantes ao talude estudado. Verificou-se que para as condições do talude natural, no auge da estação seca, as sucções matriciais são de tal magnitude que fornecem estabilidade ao talude. À medida que ocorrem precipitações, as sucções matriciais reduzem-se e o fator de segurança do talude diminui, o que justifica a ruptura ocorrida. / In this article is showing an slope back analysis in unsaturated soil. The slope, with about 15 m of height, it is composed of a fine to medium clayey sand, with degree of saturation of the order of 55% and SPT varying among 4 blows in the top to 13 blows in the base. The following properties of the soil were determined: resistance, saturated and unsaturated conductivity and it curves of retention, besides measuring the suction along the year. Parametric analyses were made to evaluate the effect of the precipitation in the changes of the ground matricial suction profile and its implications in the resistance and, by extension, in the slope stability. They were also made, some abaci that include the effect of the matricial suction variation, usable for slopes with similar characteristics to the studied slope. It was verified that for the conditions of the natural slope, next to the peak of the dry station, the matricial suction is of such magnitude that it supply stability to the slope. In the successive events of precipitations the matricials suctions is reduced and the slope security factor decreases, that justifies the happened rupture.
13

Retroanálise de escorregamentos em solos residuais não saturados / Back analysis the landslides in residual soils unsaturated

Alexandre Cerqueira de Jesus 29 August 2008 (has links)
Foram estudados cinco casos históricos de escorregamentos ocorridos na cidade de Salvador - Bahia, através do levantamento e tratamento dos dados preexistentes. Também foram realizados ensaios complementares através da instrumentação em campo com tensiômetros e ensaios de laboratório. A retroanálise, objetivo central desse trabalho foi realizada a partir das geometrias de cada uma das encostas, antes e após a ruptura resultando na definição dos possíveis parâmetros médios de resistência ao cisalhamento. Secundariamente foram realizadas análises de estabilidade convencional para a avaliação dos fatores de segurança de cada encosta, com os parâmetros de resistência na condição não saturada e saturada. Por fim foram efetuadas simulações numéricas que visavam reproduzir as condições que levaram à ruptura da encosta do Alto do Bom Viver, baseado nos conceitos da mecânica dos solos não saturados. Os resultados mostram que a maioria dos escorregamentos estudados, ocorre no horizonte do solo residual maduro, onde o valor de ângulo de atrito médio é 34º, condizente com as superfícies de rupturas pouco profundas observadas em campo. As análises paramétricas sugerem que o mecanismo de ruptura mais provável esteja relacionado à diminuição da coesão aparente do solo em virtude da diminuição da sucção. / Five historical cases of landslides in the city of Salvador, Bahia, were studied through the survey and treatment of the preexistent data. Complementary experiments were accomplished through the instrumentation field using tensiometers and laboratory testing. The back-analysis, main objective of this research, was accomplished through the geometries of each slope, before and after the rupture, resulting in the definition of the possible medium parameters of resistance to shear. Secondary, analysis of the conventional stability to the evaluation of safety factors of each slope was accomplished, with the parameters of resistance in the unsaturated and saturated condition. At last, numerical simulations were done, aiming at reproducing the conditions which led to the rupture of the slope of Alto do Bom Viver, based on the concepts of mechanics of non saturated soil. The results demonstrated that the majority of the slips studied occur in the horizon of the mature residual soil, where the value of the angle of the medium attrition is of 34 degrees, suitable with the surface of little deep ruptures observed in the field. The parametric analysis suggests that the most probable mechanism of rupture is related to the decrease of the apparent cohesion of the soil due to the decrease of suction.
14

Retroanálise probabilista: aplicação prática de análise de percolação em uma barragem de terra. / Probabilistic back-analysis: practical application of seepage analysis in an earth dam.

Elieni Guimarães Barbosa Strufaldi 07 July 2004 (has links)
O projeto de engenharia é desenvolvido baseado em um modelo de comportamento da estrutura a ser construída. Por sua vez, este modelo incorpora uma série de hipóteses de trabalho que, durante a fase de construção ou de utilização da obra, podem não ser observadas na sua totalidade. Dentro deste cenário, a retroanálise probabilista mostra-se uma ferramenta poderosa para avaliação contínua das hipóteses de trabalho durante a construção e toda a vida útil da estrutura, uma vez que permite incorporar novas informações ao modelo inicial através de métodos formalizados. Este trabalho apresenta uma revisão da retroanálise probabilista e sua aplicação prática na atualização do campo de permeabilidades de uma barragem de terra existente, com base em leituras piezométricas. Os resultados do estudo permitiram rever os valores dos parâmetros do modelo adotado, isto é, as permeabilidades dos diversos materiais, sugerindo ao mesmo tempo a aceitação do próprio modelo. Um estudo paramétrico destaca a importância relativa, para a retroanálise probabilista, das diversas variáveis envolvidas, indicando assim áreas em que a investigação complementar é mais necessária. / The engineering project is based upon a model that can predict the behavior of the facility to be constructed. Such model incorporates a series of working hypotheses which may or may not be fully realized during construction or operation. Under such circumstances, probabilistic back-analysis is a powerful tool for continuous evaluation of the working hypotheses, during construction and throughout the lifespan of the structure, given that it provides for the formal updating of the initial model and its parameters on the basis of incoming information. This study presents a review of probabilistic back-analysis and a practical application to the updating of the permeability field of an earth embankment, on the basis of piezometer readings. Results of the study led to updating of the parameters of the adopted model, that is, permeabilities of the several materials, while suggesting acceptance of the model itself. A parametric study reveals the relative importance of the several variables involved in the probabilistic back-analysis, thus indicating areas in which complementary research is mostly needed.
15

Retroanálise probabilista aplicada à análise dinâmica da cravação de estacas. / Probabilistic back-analysis applied to dynamic loading test for pile driving.

Rojas Saldívar, Raúl Eliseo 22 April 2008 (has links)
Um ensaio de carga dinâmica pode ser efetuado em tubulões, estacas hélice continua, estacas moldadas in situ ou estacas cravadas. Tal ensaio se baseia na Teoria da Propagação de Onda em estacas e visa avaliar a capacidade de carga estática mobilizada a partir do evento dinâmico. A análise do ensaio é feita mediante um programa (p.e. CAPWAP ou DLTWAVE), computacional que leva em conta tanto os sinais de força e velocidade obtidas em campo e o modelo do sistema estaca-solo Este trabalho apresenta uma metodologia para atualização bayesiana dos parâmetros de Smith da teoria de propagação de onda, levando em conta não só os sinais registrados, mas também a informação geotécnica-probabilista prévia sobre estes parâmetros. Uma aproximação semelhante já foi aplicada pelo orientador da pesquisa à estimativa de parâmetros geotécnicos de rochas a partir de medidas de deslocamento em túneis, e de campos de permeabilidade a partir de observações piezométricas em barragens. A técnica proposta está baseada firmemente em conhecimento empírico geotécnico que fornece o ensaio e erro do procedimento usual de comparação de sinais: a atualização bayesiana permite aos parâmetros afetados por incerteza maior ter um ajuste proporcionalmente maior de acordo com observações. O máximo deslocamento elástico (quake), o fator de amortecimento (damping) e a resistência estática unitária, de cada trecho da estaca, são considerados variáveis aleatórias com distribuições prévias estimadas dependendo do local de cravação da estaca. Discute-se e calcula-se a correlação cruzada entre parâmetros diferentes e autocorrelação ao longo de profundidade da estaca. As observações são escolhidas do sinal calculado por um software de análise de sinais de cravação, em espaços regulares ao longo do tempo. Postula-se um modelo linear de observação, pesquisa-se tal linearidade, também, deriva-se uma matriz de sensibilidade (ligando cada parâmetro a cada observação), e estimam-se também as incertezas nas observações (sinais). O resultado final é uma distribuição de parâmetros de Smith ao longo da profundidade de estacas, atualizada de acordo com as observações. A aproximação proposta é aplicada em sinais de um dos momentos da cravação, no final da cravação (\'end of driving\', EOD). / An dynamic loading test can be performed in concrete piles, bored piles, drilled shafts, auger cast-in-place (continuous flight auger) piles. Such essay bases on the Theory of the Propagation of Wave in piles with the aim of evaluate the capacity of static load mobilized from the dynamic event. The analysis of the test is made by a PC program (p.e. CAPWAP or DLTWAVE), that takes into account the signals of force and velocity obtained in field and the pile-soil model. This work presents a methodology for bayesian updating of Smith\'s parameters, taking into account not just the recorded signals, but also the prior geotechnical-probabilistic information about these parameters. A similar approach has already been applied by the senior author to the estimation of rock geotechnical parameters from displacement measurements in tunnels, and of permeability fields in embankment dams from piezometric observations. The proposed technique is deemed more firmly based on sound geotechnical knowledge than the usual trial and error signal matching procedure: bayesian updating allows for parameters affected by larger uncertainty to undergo proportionately larger adjustment according to observations. Quake, damping and static resistance are considered random variables, with prior distributions assessed from information about the geotechnical characteristics of the soils the pile is driven into. Cross-correlation between different parameters and auto-correlation along pile depth are discussed and estimated. Signals measured at some properly selected times are the chosen observations. A linear observation model, linking observations to parameters, is postulated, linearity is investigated, a sensitivity matrix (linking each parameter to each observation) is derived, and uncertainty in the observations (signals) is estimated. The final result is a distribution of Smith\'s parameters along pile depth, updated in accordance with the observations. The proposed approach is tested in end of driving (EOD) signal.
16

Linear viscoelastic characterization of bituminous mixtures from dynamic tests back analysis / Caractérisation viscoélastique linéaire des enrobés bitumineux par analyse inverse d’essais dynamiques

Carret, Jean-Claude 11 December 2018 (has links)
La caractérisation du comportement des matériaux bitumineux est primordiale pour pouvoir dimensionner les structures de chaussées, mais aussi pour prédire de manière plus précise leur durée de vie. En effet, ces matériaux sont soumis à des phénomènes complexes, mécaniques, thermiques, physiques et chimiques qui apparaissent souvent de manière couplée. Devant la complexité des problèmes observés et avec l’apparition des nouveaux matériaux et nouvelles techniques de fabrication, des études avancées de laboratoire et des modélisations rhéologiques sont nécessaires. Les méthodes existantes permettent de caractériser les matériaux en laboratoire grâce à l’utilisation de presses hydrauliques très couteuses. De plus, la plupart de ces essais ne sont pas adaptés à une utilisation directe sur chaussées. Dans cette thèse, un essai dynamique qui repose sur le phénomène de propagation d’onde a été développé pour caractériser les enrobés bitumineux dans le domaine viscoélastique linéaire. Il s’agit d’un essai non destructif, bien moins couteux que les essais existants et qui pourrait à terme s’adapter à une utilisation in-situ. Des méthodes complexes d’analyse inverse de propagation d’ondes en milieu viscoélastique ont été mises au point afin d’obtenir les propriétés thermomécaniques des enrobés bitumineux à partir des signaux mesurés expérimentalement. Les propriétés viscoélastiques linéaires de différents enrobés bitumineux déterminées à partir de l’essai dynamique développé ont été comparées aux résultats obtenus avec des essais cycliques plus conventionnels de traction-compression. / Characterizing the behaviour of bituminous materials is essential for the design of pavement structures and to predict their service life more accurately. Indeed, these materials are subjected to complex phenomenon, mechanical, thermal, physical and chemical that are often coupled. Due to the complexity of the phenomenon observed and with the emergence of new materials and new production techniques, advances laboratories studies and rheological modelling are necessary. With the existing methods, it is possible to characterize the materials in laboratories using expensive hydraulic presses. Moreover, most of these tests cannot be used directly on pavement structures. In this thesis, a dynamic test based on wave propagation was developed to characterize bituminous mixtures in the linear viscoelastic domain. It is a nondestructive test, far less expensive than the existing tests and that could be adapted for in situ measurements. Complex methods of inverse analysis of wave propagation in a viscoelastic medium were developed to obtain the thermomechanical properties of bituminous mixtures from the signals measured experimentally. The linear viscoelastic properties of different mixtures obtained from the developed dynamic test were compared to the results of more conventional cyclic tension-compression tests.
17

Landslide Stabilization In Weathered Tuffite, Northern Turkey

Avsar, Ozgur 01 December 2004 (has links) (PDF)
A landslide occurred during the construction of the Giresun &ndash / Espiye road between Km: 1+030 &ndash / 1+170 in April 2003. Investigating the causes and mechanism of this slope failure along with suggesting a proper stabilization technique is aimed in this study. For that purpose, a detailed site investigation study, including engineering geological mapping, drilling work, in situ and laboratory tests, was performed. Weathered tuffite, tuffite, flysch and dacitic tuffite, from top to bottom, are the major units in the study area. A &ldquo / translational slide&rdquo / occurred in completely weathered tuffite owing to the disturbance of the stability of the slope by the excavations performed at the toe of the slope / particularly the foundation excavation for the restaurant building and for the road cut for the Giresun &ndash / Espiye road. After establishing the model of the landslide in detail, shear strength parameters of the failure surface were determined by the back analysis method as &quot / cohesion&quot / =2.5 kN/m2 and &quot / friction angle&quot / =9&deg / . Toe buttressing, ground water and surface water drainage options were considered for stabilizing the slope. For the back analysis calculations, the Morgenstern-Price and Spencer methods were used with the aid of the SLOPE/W computer program.
18

Retroanálise probabilista aplicada à análise dinâmica da cravação de estacas. / Probabilistic back-analysis applied to dynamic loading test for pile driving.

Raúl Eliseo Rojas Saldívar 22 April 2008 (has links)
Um ensaio de carga dinâmica pode ser efetuado em tubulões, estacas hélice continua, estacas moldadas in situ ou estacas cravadas. Tal ensaio se baseia na Teoria da Propagação de Onda em estacas e visa avaliar a capacidade de carga estática mobilizada a partir do evento dinâmico. A análise do ensaio é feita mediante um programa (p.e. CAPWAP ou DLTWAVE), computacional que leva em conta tanto os sinais de força e velocidade obtidas em campo e o modelo do sistema estaca-solo Este trabalho apresenta uma metodologia para atualização bayesiana dos parâmetros de Smith da teoria de propagação de onda, levando em conta não só os sinais registrados, mas também a informação geotécnica-probabilista prévia sobre estes parâmetros. Uma aproximação semelhante já foi aplicada pelo orientador da pesquisa à estimativa de parâmetros geotécnicos de rochas a partir de medidas de deslocamento em túneis, e de campos de permeabilidade a partir de observações piezométricas em barragens. A técnica proposta está baseada firmemente em conhecimento empírico geotécnico que fornece o ensaio e erro do procedimento usual de comparação de sinais: a atualização bayesiana permite aos parâmetros afetados por incerteza maior ter um ajuste proporcionalmente maior de acordo com observações. O máximo deslocamento elástico (quake), o fator de amortecimento (damping) e a resistência estática unitária, de cada trecho da estaca, são considerados variáveis aleatórias com distribuições prévias estimadas dependendo do local de cravação da estaca. Discute-se e calcula-se a correlação cruzada entre parâmetros diferentes e autocorrelação ao longo de profundidade da estaca. As observações são escolhidas do sinal calculado por um software de análise de sinais de cravação, em espaços regulares ao longo do tempo. Postula-se um modelo linear de observação, pesquisa-se tal linearidade, também, deriva-se uma matriz de sensibilidade (ligando cada parâmetro a cada observação), e estimam-se também as incertezas nas observações (sinais). O resultado final é uma distribuição de parâmetros de Smith ao longo da profundidade de estacas, atualizada de acordo com as observações. A aproximação proposta é aplicada em sinais de um dos momentos da cravação, no final da cravação (\'end of driving\', EOD). / An dynamic loading test can be performed in concrete piles, bored piles, drilled shafts, auger cast-in-place (continuous flight auger) piles. Such essay bases on the Theory of the Propagation of Wave in piles with the aim of evaluate the capacity of static load mobilized from the dynamic event. The analysis of the test is made by a PC program (p.e. CAPWAP or DLTWAVE), that takes into account the signals of force and velocity obtained in field and the pile-soil model. This work presents a methodology for bayesian updating of Smith\'s parameters, taking into account not just the recorded signals, but also the prior geotechnical-probabilistic information about these parameters. A similar approach has already been applied by the senior author to the estimation of rock geotechnical parameters from displacement measurements in tunnels, and of permeability fields in embankment dams from piezometric observations. The proposed technique is deemed more firmly based on sound geotechnical knowledge than the usual trial and error signal matching procedure: bayesian updating allows for parameters affected by larger uncertainty to undergo proportionately larger adjustment according to observations. Quake, damping and static resistance are considered random variables, with prior distributions assessed from information about the geotechnical characteristics of the soils the pile is driven into. Cross-correlation between different parameters and auto-correlation along pile depth are discussed and estimated. Signals measured at some properly selected times are the chosen observations. A linear observation model, linking observations to parameters, is postulated, linearity is investigated, a sensitivity matrix (linking each parameter to each observation) is derived, and uncertainty in the observations (signals) is estimated. The final result is a distribution of Smith\'s parameters along pile depth, updated in accordance with the observations. The proposed approach is tested in end of driving (EOD) signal.
19

Analýza stability svahu náchylného k sesouvání / Analysis of slope prone to sliding

Píchová, Sylvie January 2020 (has links)
The diploma thesis illustrates landslide investigation, geophysical and engineering-geological landslide survey and landslide stability reconnaissance. Static calculations based on FEM were performed in the GEO5 program. A back analysis of the landslide mathematical model was executed, which resulted in the reliability of the static landslide assessment. The complicated stabilization construction of the pile and micropile walls were optimized by mathematical modeling of successive phases of construction. The method of execution of construction work during the landslide rehabilitation was designed as well as the dimensions of reinforcing structures.
20

Back analysis of rock mass properties in the regional fault zone under Lake Mälaren

Liu, Jiaqi January 2022 (has links)
The properties of the surrounding rock mass in underground projects have significant impacts on the design and construction. However, it is quite challenging to evaluate rock mass properties due to the great uncertainties of the geological conditions. Besides, even if techniques of field test have obtained a well development, the high expense of tests and scattering results always make it difficult to cover a large domain in a complex project. In recent years, because of the maturity of numerical analysis as well as the wide use of tunnel deformation measurements, displacement-based back analysis has become a popular and effective indirect method to estimate rock mass properties.The main purpose of this thesis was to perform a displacement-based back analysis on the in-situ stress ratio and Young’s modulus of the exploratory tunnel BP201, which constitutes the passage under the Lake Mälaren in the Stockholm Bypass project. The back analysis was carried out using the Pattern search method and the Simplex method. The error function was built according to the least square method, and the commercial finite element software Plaxis 2D was used to calculate theoretical deformations. Moreover, a sensitivity analysis was performed to study the influence of starting point and how other numerical model parameters affects the results of the back analysis.The two optimization algorithms used in this study provided an in-situ stress ratio and Young’s modulus with close estimations to the measured deformations. For the specific problem analysed in this thesis, it was found that the Simplex method was more suitable than the Pattern search method. It was also concluded that a better choice of starting point can improve the precision and efficiency of the back analysis. / Bergmassans egenskaper har en stor påverkan vid dimensioneringen och utformningen av förstärkningen i tunnlar och vid indelningen av uttagssekvenser vid tunneldrivning. Det är emellertid svårt att utvärdera bergmassans egenskaper till följd av stora osäkerheter i de geologiska förhållandena. Även om tekniker för provning i fält har utvecklats är de relativt kostsamma och det är svårt att täcka in hela den geologiska domänen i stora projekt. På senare år har utvecklingen av numeriska metoder och deformationsmätningar i tunnlar möjliggjort bestämning av bergmassans egenskaper genom deformationsbaserad bakåtanalys.Syftet med detta examenarbete var att utföra en deformationsbaserad bakåtanalys av in-situ spänningstillståndet och bergmassans elasticitets-modul i bypass tunneln BP 201 under passagen av sjön Mälaren i Stockholm, vilket är en del av projektet Förbifart Stockholm. I bakåt-analysen användes metoderna ”the Pattern Search Method” och ”the Simplex Metod”. Minsta kvadratmetoden användes som felfunktion. Tvådimensionella numeriska beräkningar av deformationerna i tunneln utfördes med det finita elementprogrammet Plaxis 2D. En känslighets-analys gjordes för att studera inverkan på resultatet vid val av startpunkt i bakåtanalysen och hur osäkerheter i övriga parametrar påverkade resultatet.De två optimeringsalgoritmerna som användes i denna studie resulterade i in-situ spänningar och en elasticitetsmodul som genererade beräknade deformationer nära de uppmätta. For det studerade problemet i detta arbete var ”the Simplex Method” lämpligare att använda än ”the Pattern Search Method”. Genom att välja ett lämpligare startvärde kunde också precisionen och effektiviteten i bakåtanalysen förbättras.

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