The effects of basin edge slope on the dynamic response of soil deposits are assessed by using one-dimensional and two-dimensional numerical analyses. 24 basin models having trapezoidal cross section are generated to represent different geometries (basin depth, basin edge slope) and soil type. Harmonic base motions with different predominant periods (Tp) are used in the analyses. The results indicate that, for a constant basin edge slope and a constant ratio of fundamental period of site to the predominant period of base motion (Tn/Tp), the response is almost the same for different soil types, basin depths and base motions. In the sloping edge region, one-dimensional response analysis predictions are found to be conservative compared to two-dimensional analysis predictions / however beyond this region they are unconservatively biased by a factor as high as 1.5. The sloping edge region and the horizontal region of the basin are denoted by normalized distance (ND) values varying from 0 to 1 and 1 to 2 respectively. The critical region where maximum amplification observed falls in the range of ND=1.0 to ND=1.5 for basins having slopes greater than 30o. The lower boundary of the critical region is shifted towards as low as ND=0.2 for basins having slopes less than 30o. For a constant value of Tn/Tp, the increase in the amplification is smooth for basins with gentle slopes as compared to basins with steep slopes for the region where ND~1. For a basin and earthquake couple approaching to resonance state (Tn/Tp=1), the amplification for the region where ND is greater than 1 is found to be as high as 100% of that is found for the region where ND~1.

Among the hard-hit cities during 17 August 1999 Kocaeli Earthquake (Mw 7.4), Adapazari is known for the prominent role of site conditions in damage distribution. Since the strong ground motion during the event was recorded only on a rock site, it is necessary to estimate the response of alluvium basin before any study on the relationship between the damage and the parameters of ground motion. Therefore, a series of site and laboratory tests were done on Adapazari soils in order to decrease the uncertainty in estimation of their dynamic properties. In downtown Adapazari, a 118 m deep borehole was opened in the vicinity of heavily damaged buildings for sample recovery and in-situ testing. The stiffness of the soils in-situ is first investigated by standard penetration tests (SPT) and by velocity measurements with P-S suspension logging technique. Disturbed samples were recovered by core-barrel and split-barrel samplers. 18 Thin-Walled tubes were successively used for recovering undisturbed samples. A series of monotonic and cyclic direct simple shear tests were done on specimens recovered from the Thin-Walled tubes. It is concluded that the secant shear modulus and damping ratio of soils exposed to severe shaking during the 1999 event are significantly smaller than those estimated by using the empirical relationships in literature. It is also observed that the reversed-S shaped hysteresis loops are typical for cyclic response of the samples.

Made available in DSpace on 2015-03-26T13:40:02Z (GMT). No. of bitstreams: 1 texto completo.pdf: 725476 bytes, checksum: 9dc70a80eac3e525b33e6bd8c01a137b (MD5) Previous issue date: 2013-07-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In tropical conditions occurs variety of soil and climate. In this region there is little research on the behavior of herbicides in soils. Applications of these products without the knowledge of their interactions with soil properties and climatic conditions can be a cause of inefficiency agronomic observed infrequently, and the high risk of contamination of surface and groundwater. The tebuthiuron is one of the most commonly used herbicides in sugar cane in Brazil and its dynamics in tropical soils is poorly studied. Thus, it was held that this work was to evaluate the sorption, desorption, half-life and leaching of the herbicide tebuthiuron in Red -Yellow humic Latosol ( LVAh ), Typic. For this methods were used high performance liquid chromatography (HPLC ) and the results verified by biological methods . Three experiments were conducted, the first to determine the sorption and desorption of tebuthiuron latosols the second herbicide leaching in the soil profile and the third, the half -life in these soils. Sorption tebuthiuron followed the same trend in different soils, characterized in two phases. Initially, the sorption occurred more quickly, and then displaying a slower phase. The sorption was directly proportional to the amount of organic matter and clay soils. On the other hand, desorption was inversely proportional herbicide sorption. The leaching of tebuthiuron was higher in LV pH 5,0 and pH 6,2 and pH 6,3 LA , being reduced by higher levels of organic matter and clay . The degradation of tebuthiuron in soil followed an exponential model, and its half-life in soil is influenced by soil organic matter content, CEC and clay content. In LVA pH 5,0, the half -life of tebuthiuron was 155 days. On the same soil, with pH changed to 5,9, the half-life of this herbicide was 117 days after its application. It is concluded that the sorption, desorption and leaching half-life tebuthiuron are influenced by the chemical characteristics (CEC and organic matter) and physical (content of clay) soil. Organic matter increased the sorption and desorption and reduced leaching of tebuthiuron. On the other hand, in soils with higher CEC persistence tebuthiuron was reduced. Biological assays can be used to confirm the results of chromatography. / Nas condições tropicais ocorre grande variedade de solos e de clima. Nesta região são escassas as pesquisas sobre o comportamento dos herbicidas nos solos. Aplicações desses produtos sem o conhecimento de suas interações com os atributos dos solos e condições climáticas podem ser uma das causas da ineficiência agronômica, observadas com certa frequência, além dos elevados riscos de contaminação de águas superficiais e subterrâneas. O tebuthiuron é um dos herbicidas mais utilizados em cana-de-açúcar no Brasil e sua dinâmica nos solos tropicais é pouco estudada. Assim, realizou-se este trabalho que teve como objetivo avaliar a sorção, dessorção, meia-vida e lixiviação do herbicida tebuthiuron nos Latossolos Vermelho-Amarelo, Latossolo Vermelho-Amarelo húmico (LVAh), Latossolo Amarelo e Latossolo Vermelho. Para isso foram utilizados métodos de cromatografia liquida de alta eficiência (CLAE) sendo os resultados comprovados por métodos biológicos. Foram realizados três experimentos, sendo o primeiro para determinar a sorção e dessorção do tebuthiuron em latossolos, o segundo a lixiviação desse herbicida no perfil do solo e o terceiro, a sua meia-vida nesses solos. A sorção do tebuthiuron seguiu uma mesma tendência nos diferentes solos, caracterizando-se em duas fases. Numa fase inicial, a sorção ocorreu de forma mais rápida, e em seguida exibindo uma fase mais lenta. A sorção foi diretamente proporcional aos teores de matéria orgânica e argila nos solos. Por outro lado, a dessorção desse herbicida foi inversamente proporcional a sorção. A lixiviação do tebuthiuron foi maior nos LV pH 5,0 e pH 6,2 e LA pH 6,3, sendo reduzida por maiores teores de matéria orgânica e argila. A degradação do tebuthiuron no solo seguiu um modelo exponencial, e a sua meia-vida no solo foi influenciada pelo teor de matéria orgânica, CTC e teor de argila. No LVA pH 5,0, a meia-vida do tebuthiuron foi de 155 dias. No mesmo solo, com o pH alterado para 5,9, a meia-vida desse herbicida foi de 117 dias após sua aplicação. Conclui-se que a sorção, dessorção, meia-vida e lixiviação do tebuthiuron são influenciadas pelas características químicas (matéria orgânica e CTC) e físicas (teor de argila) do solo. A matéria orgânica aumentou a sorção e reduziu a dessorção e a lixiviação do tebuthiuron. Por outro lado em solos com maior CTC a persistência do tebuthiuron foi reduzida. Os ensaios biológicos podem ser utilizados na confirmação dos resultados da cromatografia.

Orientadores: Aloisio Ernesto Assan, Persio Leister de Almeida Barros / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-11T01:26:45Z (GMT). No. of bitstreams: 1 BobadillaGuadalupe_Ulises_D.pdf: 1151597 bytes, checksum: 005fbfba6e1ebd787b740be4f94cbf34 (MD5) Previous issue date: 2008 / Resumo: As características que determinam o comportamento de uma estrutura sob carregamento dinâmico são as massas dos vários elementos, a rigidez dos seus membros e a dissipação de energia. Para avaliar corretamente a resposta dinâmica de uma estrutura levando em conta os efeitos da interação, é necessário incorporar as propriedades dinâmicas do solo dentro da formulação matemática do modelo físico adotado. Referido à superestrutura, os efeitos da interação alteram a resposta estrutural final, devido à inter-relação dinâmica entre o movimento do solo e o movimento da base de fundação. Conseqüentemente, se primeiro se avalia o movimento da base de fundação [produto da interação solo-estrutura (SSI)], a resposta estrutural final poderá ser resolvida depois via análise modal da superestrutura. Esta conceituação é utilizada no presente trabalho. Aqui, todo o processo de análise é feito no domínio da freqüência. A resposta estrutural é avaliada através da chamada Transformada Implícita de Fourier (ImFT), implementando-se para isto um algoritmo computacional que avalia a resposta dinâmica utilizando a ImFT eficientemente. A ImFT é uma avaliação racional das matrizes envolvendo as transformadas discretas de Fourier (DFT), para num mesmo processo matricial achar a resposta dinâmica estrutural diretamente no domínio do tempo. Correntemente, para a análise no domínio da freqüência tem-se utilizado a FFT (Fast Fourier Transform); embora a FFT seja computacionalmente eficiente, apresenta-se aqui a ImFT, um outro processo computacional alternativo à FFT e bastante eficiente para certos tipos de carregamento tais como uma excitação sísmica, que é o carregamento utilizado nesta pesquisa / Abstract: The characteristics that determine the behavior of a structure under dynamic loading are the masses of various elements, the rigidity of its members and the dissipation of energy. To properly evaluate the dynamic response of a structure taking into account the effects of the interaction, it is necessary to incorporate the dynamic properties of the soil within the mathematical formulation of the physical model adopted. Referred to the superstructure, the effects of interaction modify the final structural response due to the dynamic interrelationship between the soil motion and the base of foundation motions. Consequently, if that first assesses the base of foundation motions [product of the soil-structure interaction effects (SSI)], the final structural response can be assessed later by modal analysis of the superstructure. This concept is used in this work. Here, the whole process of analysis is done in frequency domain. The structural response is evaluated by the so-called Implicit Fourier Transform (ImFT), implementing to this a computational algorithm that assesses the structural dynamic response using the ImFT efficiently. The ImFT is a rational assessment of matrices involving the Discrete Fourier Transform (DFT) for a same matrix process find structural dynamics response directly on time domain. Commonly, for the analysis in the frequency domain has been used the FFT (Fast Fourier Transform), although the FFT is efficiently, presents itself here the ImFT, another alternative computational algorithm and quite competent to certain types of loading such as a seismic excitation which is the loading used in this study / Doutorado / Estruturas / Doutor em Engenharia Civil

L'interaction dynamique sol-structure a été largement explorée en supposant le comportement linéaire du sol. Néanmoins, pour des séismes d'intensité modérée à forte, la contrainte de cisaillement maximale peut facilement atteindre la limite élastique du sol. Du point de vue de l'interaction sol-structure, les effets non linéaires peuvent modifier la rigidité du sol à la base de la structure ainsi que la quantité d'énergie dissipée dans le sol. En conséquence, ignorer les caractéristiques non linéaires du sol dans l'interaction dynamique sol-structure (IDSS) peut conduire à des prédictions erronées de la réponse de la structure. Le but de ce travail est d'implémenter dans un code numérique une loi de comportement non linéaire pour le sol afin d'examiner l'effet de la nonlinéarité du sol sur l'interaction dynamique sol-structure. De plus, différents aspects sont pris en compte tels que l'effet de la contrainte de confinement sur le module de cisaillement du sol, les conditions statiques initiales, les conditions d'interface entre le sol et la structure, etc. Durant ce travail, une méthode simple de couche absorbante basée sur une formulation de Rayleigh / Caughey pour l'amortissement, qui est généralement disponible dans les logiciels existants d'éléments finis, a également été développée. Les conditions de stabilité des problèmes de propagation d'onde sont étudiées et on montre que les comportements linéaire et non linéaire sont très différents en ce qui concerne la dispersion numérique. La règle habituelle de 10 points par longueur d'onde, recommandée dans la littérature pour les milieux élastiques, apparaît pas suffisante dans le cas non linéaire.Le modèle implémenté est d'abord vérifié numériquement en comparant les résultats avec ceux d'autres codes numériques connus. Après cela, une étude paramétrique est menée pour différents types de structures et des profils de sol variés afin de caractériser les effets non linéaires. Différentes caractéristiques de l'IDSS sont comparées à celles du cas linéaire: modification de l'amplitude et du contenu fréquentiel des ondes se propageant dans le sol, fréquence fondamentale, dissipation de l'énergie dans le sol et réponse du système sol-structure. A travers ces études paramétriques nous montrons qu'en fonction des propriétés du sol, le contenu fréquentiel de la réponse du sol peut changer significativement à cause des nonlinéarités de comportement. Les pics de la fonction de transfert entre le champ libre et le rocher affleurant se décalent vers les basses fréquences et l'amplification se produit dans cette gamme de fréquences. Une réduction de l'amplification pour les hautes fréquences et même une dé-amplification peuvent se produire pour un fort niveau des mouvements d'entrée. Ces changements influencent la réponse de la structure. Ce travail montre également que la proximité des fréquences fondamentales de la structure et du sol influence fortement l'interaction sol-structure. Enfin, l'effet du poids de la structure et du balancement de la superstructure peut être significatif. Finalement, le bassin de Nice est utilisé comme un exemple de propagation d'onde dans un milieu non linéaire hétérogène et d'interaction dynamique sol-structure. La réponse du bassin dépend fortement de la combinaison de la nonlinéarité du sol, des effets topographiques et du contraste d'impédance entre les couches de sol. Pour les structures et les profils de sol sélectionnés dans ce travail, les simulations numériques réalisées montrent que le décalage de la fréquence fondamentale n'est pas un bon indicateur pour distinguer le comportement linéaire du sol du comportement non linéaire / The interaction of the soil with the structure has been largely explored the assumption of material and geometrical linearity of the soil. Nevertheless, for moderate or strong seismic events, the maximum shear strain can easily reach the elastic limit of the soil behavior. Considering soil-structure interaction, the nonlinear effects may change the soil stiffness at the base of the structure and therefore energy dissipation into the soil. Consequently, ignoring the nonlinear characteristics of the dynamic soil-structure interaction (DSSI) this phenomenon could lead toerroneous predictions of structural response. The goal of this work is to implement a fully nonlinear constitutive model for soils into anumerical code in order to investigate the effect of soil nonlinearity on dynamic soil structureinteraction. Moreover, different issues are taken into account such as the effect of confining stress on the shear modulus of the soil, initial static condition, contact elements in the soil-structure interface, etc. During this work, a simple absorbing layer method based on a Rayleigh / Caughey damping formulation, which is often already available in existing. Finite Element softwares, is also presented. The stability conditions of the wave propagation problems are studied and it is shown that the linear and nonlinear behavior are very different when dealing with numerical dispersion. It is shown that the 10 points per wavelength rule, recommended in the literature for the elastic media is not sufficient for the nonlinear case. The implemented model is first numerically verified by comparing the results with other known numerical codes. Afterward, a parametric study is carried out for different types of structures and various soil profiles to characterize nonlinear effects. Different features of the DSSI are compared to the linear case : modification of the amplitude and frequency content of the waves propagated into the soil, fundamental frequency, energy dissipation in the soil and the response of the soil-structure system. Through these parametric studies we show that depending on the soil properties, frequency content of the soil response could change significantly due to the soil nonlinearity. The peaks of the transfer function between free field and outcropping responsesshift to lower frequencies and amplification happens at this frequency range. Amplificationreduction for the high frequencies and even deamplication may happen for high level inputmotions. These changes influence the structural response.We show that depending on the combination of the fundamental frequency of the structureand the the natural frequency of the soil, the effect of soil-structure interaction could be significant or negligible. However, the effect of structure weight and rocking of the superstructurecould change the results. Finally, the basin of Nice is used as an example of wave propagation ona heterogeneous nonlinear media and dynamic soil-structure interaction. The basin response isstrongly dependent on the combination of soil nonlinearity, topographic effects and impedancecontrast between soil layers. For the selected structures and soil profiles of this work, the performed numerical simulations show that the shift of the fundamental frequency is not a goodindex to discriminate linear from nonlinear soil behavior

O ensaio SPT (Standard Penetration Test), é o ensaio de campo geotécnico mais usado no Brasil e grande parte do mundo. A ampla utilização deste ensaio no âmbito da engenharia geotécnica deve-se à sua simplicidade, baixo custo, grande experiência prática e facilidade de aplicação dos seus resultados. Os principais objetivos do ensaio são a determinação do índice de resistência do solo (NSPT) e amostragem. Apesar de ser muito utilizado na estimativa da capacidade de carga de fundações, o ensaio SPT tem sido questionado pelo fato de que o índice NSPT é utilizado em correlações empíricas baseadas em observações práticas, sem nenhum fundamento científico. Além do mais, seus resultados apresentam significativas dispersões. Para analisar racionalmente os resultados do ensaio e de possibilitar a comparação dos diferentes resultados de distintas equipes, é necessário conhecer as quantidades de energia envolvidas na penetração do amostrador no solo. Tais análises requerem o conhecimento da eficiência do equipamento (η) e a força de reação dinâmica do solo à cravação do amostrador (RD). Neste cenário, o presente trabalho aborda a interpretação racional dos resultados de ensaios SPT a partir de simulações numéricas realizadas com o software Abaqus/Explicit®. Esse programa fornece os deslocamentos do amostrador (Δρ), força de reação dinâmica do solo (RD), e as forças de reação nas paredes laterais externa e interna do amostrador (R1 e R2). Baseando-se nos resultados dos modelos numéricos, foi possível calcular a eficiência do equipamento, a partir da força de reação dinâmica do solo, as resistências unitárias de atrito atuantes nas paredes e a resistência unitária na ponta do amostrador. Também foi possível determinar a relação entre as resistências unitárias de atrito desenvolvidas no interior e exterior do amostrador (fator de atrito a). Os resultados obtidos foram comparados com resultados de trabalhos experimentais e valores teóricos determinados com base no Princípio de Hamilton da conservação da energia. Também foi possível simular uma prova de carga dinâmica com energia crescente no amostrador, variando a altura de queda do martelo. Isso confirmou que a resistência mobilizada do solo para certa energia aplicada pode estar bem abaixo da ruptura e apenas representar um ponto na curva de resistência mobilizada versus deslocamento. / The Standard Penetration Test (SPT) is one of the most used geotechnical tests in the world. The wide use of this test in the context of geotechnical engineering is due to its simplicity, low cost, large practical experience and its ease of application of results. The main objectives of the test are the determination of soil resistance index (NSPT) and sampling. Despite being widely used in estimating the bearing capacity of foundations, the SPT test has been questioned by the fact that the NSPT index is used in empirical correlations based on practical observations, with no scientific basis. Furthermore, its results show significant dispersions. To analyze rationally the test results and to make possible to compare different results obtained from different equipment, it is necessary to know the amounts of energy existing during the penetration of the sampler into soil. Such analyses require information about the equipment efficiency (η) and the dynamic soil reaction force during the sampler penetration (RD). In this scenario, this work addresses the rational interpretation of SPT test results from numerical simulations performed with the Abaqus/Explicit software. This program provides the sampler displacements (Δρ), the dynamic soil reaction force (RD) and the external and internal reaction forces acting on the sampler walls (R1 e R2). Based on the results of the numerical models, it was possible to calculate the efficiency of the equipment, from the dynamic soil reaction force, the unit friction resistance acting on the sampler walls and the unit resistance at the sampler tip. In addition, it was possible to estimate the relationship between the unit friction resistance acting on the internal and external walls of the sampler (friction factor a). The numerical results were compared with experimental results and theoretical values, obtained using the Hamilton\'s principle of conservation of energy. Furthermore, it was possible to simulate a dynamic load test with increasing energy applied to the sampler, by varying the height of fall of the hammer. It was obtained the confirmation that resistance mobilized for a certain level of energy applied to the sampler may be below the failure load and represent only a point on the graph curve mobilized resistance versus displacement.

Στην παρούσα εργασία, πραγματοποιείται η μελέτη του φαινομένου της δυναμικής αλληλεπίδρασης εδάφους-κατασκευής όταν αυτή θεμελιώνεται επί εύκαμπτων, επιφανειακών θεμελιώσεων με ή χωρίς πασσάλους. Η μέχρι σήμερα μελέτη της αλληλεπίδρασης εδάφους-κατασκευής έχει περιορισθεί κυρίως σε επιφανειακά, άκαμπτα ή εύκαμπτα θεμέλια και επιφανειακές ή βαθιές, άκαμπτες θεμελιώσεις επί πασσάλων. Ο συνδυασμός εύκαμπτων θεμελιώσεων, επιφανειακών ή βαθιών, και πασσαλώσεων, κοινή πρακτική σε πλείστες κατασκευές, δεν έχει μελετηθεί λόγω της περιπλοκότητας του φαινομένου και των σχετικών αβεβαιοτήτων όσον αφορά στα δεδομένα του προβλήματος. Συνεπώς, η κρισιμότητα των διαφόρων παραμέτρων, και των πολλαπλών αλληλεπιδράσεων τους, στη σεισμική απόκριση των κατασκευών παραμένει εν πολλοίς άγνωστη. Στόχος της εργασίας είναι η ανάπτυξη ενός διακριτού προσομοιώματος για τον εδαφικό ημιχώρο, το οποίο θα δύναται να χρησιμοποιηθεί για την δυναμική ανάλυση εύκαμπτων θεμελίων με ή χωρίς πασσάλους. Σε αυτή την μελέτη χρησιμοποιείται αποκλειστικά η μέθοδος των πεπερασμένων στοιχείων (ΜΠΣ), για την διακριτοποίηση της κατασκευής, του εδάφους και του συστήματος θεμελίωσης. Ειδικότερα, με τη χρήση του πακέτου πεπερασμένων στοιχείων ACS SASSI, διακριτοποιείται ο εδαφικός ημιχώρος και υπολογίζεται το πεδίο μετακινήσεων της επιφάνειας του ημιχώρου για διάφορες συχνότητες που αντιστοιχούν σε συνήθεις σεισμικές διεγέρσεις. Με γνωστό το πεδίο μετακινήσεων, υπολογίζονται οι δυναμικές δυσκαμψίες του ημιχώρου συναρτήσει της συχνότητας και της απόστασης από το σημείο φόρτισης και δημιουργείται ένα νέο διακριτό προσομοίωμα που αντικαθιστά το έδαφος, με βάση το μητρώο δυναμικών δυσκαμψιών. Τέλος με κατάλληλη αδιαστατοποίηση, προκύπτουν κλειστές εκφράσεις για τα στοιχεία του μητρώου δυναμικών δυσκαμψιών, που παρέχουν το επιπλέον πλεονέκτημα ότι είναι ανεξάρτητες της συχνότητας διέγερσης και έτσι γίνεται εφικτή η απευθείας ανάλυση συστημάτων αλληλεπίδρασης εδάφους – κατασκευής στο πεδίο του χρόνου. Το προτεινόμενο προσομοίωμα του ελαστικού ημιχώρου επεκτείνεται στην περίπτωση του μεμονωμένου πασσάλου σε εδαφικό ημιχώρο. Το διακριτό προσομοίωμα που αναπτύχθηκε προηγουμένως είναι κατάλληλο για εισαγωγή σε πρόγραμμα πεπερασμένων στοιχείων γενικού σκοπού ( όπως π.χ. ANSYS, SAP2000, ABAQUS ) και μπορεί να χρησιμοποιηθεί για κάθε είδος επιφανειακής εύκαμπτης ή άκαμπτης θεμελίωσης ανεξαρτήτου γεωμετρίας, υποκαθιστώντας τον ελαστικά γραμμικό εδαφικό ημιχώρο. Με αυτό τον τρόπο γίνεται εφικτή η επίλυση οποιουδήποτε συστήματος αλληλεπίδρασης εδάφους – κατασκευής. Η ακρίβεια και αποτελεσματικότητα του προτεινόμενου προσομοιώματος για τον εδαφικό ημιχώρο, γίνεται φανερή από μια σειρά συγκρίσεων με αποτελέσματα παλαιοτέρων δημοσιεύσεων για άκαμπτα και εύκαμπτα θεμέλια και κατασκευών με ή χωρίς πασσάλους. / During the last decades the problem of dynamic soil-structure interaction (SSI), has received considerable attention due to the large number of installations and structures sensitive to dynamic excitations such as multistory buildings, bridges, nuclear reactors, platforms etc. In fact every structure that lies on a deformable soil medium, experiences the effects of dynamic SSI. Although the phenomenon is thoroughly studied for a variety of soil-structure systems the main research effort has been focused on the dynamic behavior of rigid foundations. The assumption of foundation rigidity is so popular because it simplifies the solution procedure. In contrast, the dynamic analysis of flexible foundations adds more parameters to the problem, by requiring the discretization of both the soil medium and the foundation itself. In this work, the main goal is the study of the dynamic response of flexible foundations (e.g. mat foundations, raft foundations) and the development of a new discrete model for the analysis of soil-foundation-structure systems, which incorporates the effects of foundation flexibility. The problem under consideration consists of determining the dynamic response of the surface of the soil medium idealized as a linear elastic, isotropic half space. To this end the Finite element Method (FEM) is utilized throughout this work. The FEM computer code ACS SASSI is used to simulate the half space. Using the dynamic response of half space surface due to a unit harmonic load, calculated at a dense network of surface nodal points, the impedances of the half space are computed. Using these values a simplified, frequency independent discrete impedance matrix is constructed. Results of the above analysis are presented for a range of frequencies and half-space material properties, in easy to use graphs. This model is expanded to incorporate the case of a single flexible pile embedded on a homogenous half space. The above discrete model can easily be imported to any standard general purpose FEM code (e.g., ANSYS, SAP2000), where the solution of the soil-structure system can be obtained for a variety of soil-structure systems. The main advantages of this model are 1) Accurate, easy and fast discretization of the soil medium 2) No limitation exist due to foundation type or geometry 3) Analyses can be performed both in frequency and time domain.

The interaction of the soil with the structure has been largely explored the assumption of material and geometrical linearity of the soil. Nevertheless, for moderate or strong seismic events, the maximum shear strain can easily reach the elastic limit of the soil behavior. Considering soil-structure interaction, the nonlinear effects may change the soil stiffness at the base of the structure and therefore energy dissipation into the soil. Consequently, ignoring the nonlinear characteristics of the dynamic soil-structure interaction (DSSI) this phenomenon could lead toerroneous predictions of structural response. The goal of this work is to implement a fully nonlinear constitutive model for soils into anumerical code in order to investigate the effect of soil nonlinearity on dynamic soil structureinteraction. Moreover, different issues are taken into account such as the effect of confining stress on the shear modulus of the soil, initial static condition, contact elements in the soil-structure interface, etc. During this work, a simple absorbing layer method based on a Rayleigh / Caughey damping formulation, which is often already available in existing. Finite Element softwares, is also presented. The stability conditions of the wave propagation problems are studied and it is shown that the linear and nonlinear behavior are very different when dealing with numerical dispersion. It is shown that the 10 points per wavelength rule, recommended in the literature for the elastic media is not sufficient for the nonlinear case. The implemented model is first numerically verified by comparing the results with other known numerical codes. Afterward, a parametric study is carried out for different types of structures and various soil profiles to characterize nonlinear effects. Different features of the DSSI are compared to the linear case : modification of the amplitude and frequency content of the waves propagated into the soil, fundamental frequency, energy dissipation in the soil and the response of the soil-structure system. Through these parametric studies we show that depending on the soil properties, frequency content of the soil response could change significantly due to the soil nonlinearity. The peaks of the transfer function between free field and outcropping responsesshift to lower frequencies and amplification happens at this frequency range. Amplificationreduction for the high frequencies and even deamplication may happen for high level inputmotions. These changes influence the structural response.We show that depending on the combination of the fundamental frequency of the structureand the the natural frequency of the soil, the effect of soil-structure interaction could be significant or negligible. However, the effect of structure weight and rocking of the superstructurecould change the results. Finally, the basin of Nice is used as an example of wave propagation ona heterogeneous nonlinear media and dynamic soil-structure interaction. The basin response isstrongly dependent on the combination of soil nonlinearity, topographic effects and impedancecontrast between soil layers. For the selected structures and soil profiles of this work, the performed numerical simulations show that the shift of the fundamental frequency is not a goodindex to discriminate linear from nonlinear soil behavior

O ensaio SPT (Standard Penetration Test), é o ensaio de campo geotécnico mais usado no Brasil e grande parte do mundo. A ampla utilização deste ensaio no âmbito da engenharia geotécnica deve-se à sua simplicidade, baixo custo, grande experiência prática e facilidade de aplicação dos seus resultados. Os principais objetivos do ensaio são a determinação do índice de resistência do solo (NSPT) e amostragem. Apesar de ser muito utilizado na estimativa da capacidade de carga de fundações, o ensaio SPT tem sido questionado pelo fato de que o índice NSPT é utilizado em correlações empíricas baseadas em observações práticas, sem nenhum fundamento científico. Além do mais, seus resultados apresentam significativas dispersões. Para analisar racionalmente os resultados do ensaio e de possibilitar a comparação dos diferentes resultados de distintas equipes, é necessário conhecer as quantidades de energia envolvidas na penetração do amostrador no solo. Tais análises requerem o conhecimento da eficiência do equipamento (η) e a força de reação dinâmica do solo à cravação do amostrador (RD). Neste cenário, o presente trabalho aborda a interpretação racional dos resultados de ensaios SPT a partir de simulações numéricas realizadas com o software Abaqus/Explicit®. Esse programa fornece os deslocamentos do amostrador (Δρ), força de reação dinâmica do solo (RD), e as forças de reação nas paredes laterais externa e interna do amostrador (R1 e R2). Baseando-se nos resultados dos modelos numéricos, foi possível calcular a eficiência do equipamento, a partir da força de reação dinâmica do solo, as resistências unitárias de atrito atuantes nas paredes e a resistência unitária na ponta do amostrador. Também foi possível determinar a relação entre as resistências unitárias de atrito desenvolvidas no interior e exterior do amostrador (fator de atrito a). Os resultados obtidos foram comparados com resultados de trabalhos experimentais e valores teóricos determinados com base no Princípio de Hamilton da conservação da energia. Também foi possível simular uma prova de carga dinâmica com energia crescente no amostrador, variando a altura de queda do martelo. Isso confirmou que a resistência mobilizada do solo para certa energia aplicada pode estar bem abaixo da ruptura e apenas representar um ponto na curva de resistência mobilizada versus deslocamento. / The Standard Penetration Test (SPT) is one of the most used geotechnical tests in the world. The wide use of this test in the context of geotechnical engineering is due to its simplicity, low cost, large practical experience and its ease of application of results. The main objectives of the test are the determination of soil resistance index (NSPT) and sampling. Despite being widely used in estimating the bearing capacity of foundations, the SPT test has been questioned by the fact that the NSPT index is used in empirical correlations based on practical observations, with no scientific basis. Furthermore, its results show significant dispersions. To analyze rationally the test results and to make possible to compare different results obtained from different equipment, it is necessary to know the amounts of energy existing during the penetration of the sampler into soil. Such analyses require information about the equipment efficiency (η) and the dynamic soil reaction force during the sampler penetration (RD). In this scenario, this work addresses the rational interpretation of SPT test results from numerical simulations performed with the Abaqus/Explicit software. This program provides the sampler displacements (Δρ), the dynamic soil reaction force (RD) and the external and internal reaction forces acting on the sampler walls (R1 e R2). Based on the results of the numerical models, it was possible to calculate the efficiency of the equipment, from the dynamic soil reaction force, the unit friction resistance acting on the sampler walls and the unit resistance at the sampler tip. In addition, it was possible to estimate the relationship between the unit friction resistance acting on the internal and external walls of the sampler (friction factor a). The numerical results were compared with experimental results and theoretical values, obtained using the Hamilton\'s principle of conservation of energy. Furthermore, it was possible to simulate a dynamic load test with increasing energy applied to the sampler, by varying the height of fall of the hammer. It was obtained the confirmation that resistance mobilized for a certain level of energy applied to the sampler may be below the failure load and represent only a point on the graph curve mobilized resistance versus displacement.

In the built environment, human activities such as railway and road traffic, constructionworks or industrial manufacturing can give rise to ground borne vibrations. Such vibrations become a concern in urban areas as they can cause human discomfort or disruption of vibration sensitive equipment in buildings. In Sweden, geological formations of soft clay soils overlying till and a high quality bedrock are encountered in densely populated areas, which are soil conditions that are prone to high levels of ground borne vibrations. Under such soil conditions, end-bearing piles are often used in the design of building foundations. The dynamic response of a building is governed by the interaction between the soil and the foundation. It is therefore essential that models used for vibration predictions are able to capture the dynamic soil-structure interaction of pile foundations. The purpose of this thesis is to experimentally and numerically investigate dynamic soil-structure interaction of an end-bearing pile group in clay by constructing a test foundation of realistic dimensions. The small-strain properties in a shallow clay deposit are estimated using different site investigation and laboratory methods. The results are synthesised into a representative soil model to compute the free-field surface response, which is validated with vibration measurements performed at the site. It is found that detailed information regarding material damping in the clay and the topmost soil layer both have a profound influence on the predicted surface response, especially with an increasing distance from the source. Dynamic impedances of four end-bearing concrete piles driven at the site are measured. Pile-soil-pile interaction is investigated by measuring the response of the neighbour piles when one of the piles in the group is excited. The square pile group is subsequently joined in a concrete cap and measurements of the impedances of the pilegroup and acceleration measurements within the piles at depth are performed. A numerical model based on the identified soil properties is implemented and validated by the measurements. A good agreement between the predicted and measured responses and impedances of the pile group foundation is found, establishing confidence in the ability to predict the dynamic characteristics of end-bearing pile foundations under the studied soil conditions. / Mänsklig verksamhet i urbana miljöer så som väg- och järnvägstrafik, byggnation eller maskindrift inom industri kan ge upphov till vibrationer som sprider sig via marken i närområdet. Dessa vibrationer kan ge upphov till kännbara vibrationer eller påverka vibrationskänslig utrustning i byggnader. I Sverige förekommer ofta mjuka lerjordar ovanpå berg, och inte sällan i tätbebyggda områden. Under sådana jordförhållanden används ofta spetsbärande pålar för grundläggning av byggnader. Det dynamiska verkningssättet för byggnader är beroende av interaktionen mellan jorden och byggnadens grund. Det är därför viktigt att modeller som används för vibrationsanalys i byggnader kan beskriva denna interaktion mellan jord och byggnadsfundament. Syftet med denna avhandling är att experimentellt och via numeriska modeller studera dynamisk jord-struktur-interaktion av ett spetsbärande pålfundament i lera. Jordensmekaniska egenskaper vid små töjningar utvärderas för en lerjord som är avsatt på morän och berg genom både fältförsök och laboratorieanalyser av prover. Informationen kombineras för att konstruera en lagerförd jordmodell av platsen för att beräkna jordens dynamiska respons till följd av en punktlast. Modellen valideras med vibrationsmätningar som utförts på platsen. Studien visar att detaljerad information angående lerans materialdämpning och de mekaniska egenskaperna av jordens översta lager har en stor inverkan på förutsägelser av jordens dynamiska respons vid ytan, speciellt vid stora avstånd från vibrationskällan. Experimentella tester utförs för att mäta dynamiska impedanser av fyra slagna spetsbärande betongpålar. Interaktionen mellan pålarna utvärderas genom att utföra mätningarav de omgivande pålarnas respons till följd av excitering av en påle. Pålgruppen sammanfogas därefter i ett betongfundament och impedanserna samt accelerationer inuti pålarna uppmäts. En numerisk modell baserad på de identifierade mekaniska egenskaperna av jorden upprättas och valideras genom mätningarna. De numeriska resultaten är i god överensstämmelse med de uppmätta vilket styrker användningen av numeriska modeller för att förutsäga interaktionen mellan jord och spetsbärandepålar under de studerade jordförhållandena. / <p>QC 20210302</p>