Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 1985. / Die ontstaan van waaisand langs die Suidwes-Kaapse kus en die geskiedenis van waaisandherwinning in die gebied word behandel. Die gebruik van Ammophila arenaria (marram) en A. breviligulata tydens die herwinning van waaisand in ander lande word bespreek. Verskillende metodes kan gebruik word om die resultate van die onderskeie behandelings op die groei van marramgras te bepaal.

Située à la pointe du Médoc, la paroisse de Soulac (communes actuelles de Soulac-sur-Mer et du Verdon-sur-Mer, Gironde) est selon une expression médiévale « à la fin des terres ». Prise en tenaille entre l’Atlantique, à l’ouest, et la Gironde, à l’est, son finage comprend un long liseré littoral (14 km de rivages océaniques et 11 km de rives estuariennes) qui l’expose aux phénomènes d’origine naturelle liés à des dynamiques maritimes et fluviomaritimes. Depuis la fin du XVIe siècle, le sable accumulé le long du littoral sous la forme de dunes est porté par le vent sur les habitations et les cultures, poussant à l’abandon de l’église de Soulac et du bourg primitif au milieu du XVIIIe siècle. Parallèlement, le littoral est fortement attaqué par l’érosion qui se généralise au milieu du Siècle des Lumières. À l’est, les marais salants s’envasent, réduisant en moins d’un siècle la moitié de leur surface. Enfin, les zones basses de la paroisse sont exposées aux submersions marines, qui demeurent cependant peu fréquentes. Ce micro-espace de 50 km² constitue un bon point d’observation pour étudier les transformations d’un territoire littoral et l’adaptation des populations à ces changements. Prenant appui sur des ressources documentaires importantes (archives textuelles et cartographiques) et continues dans le temps (de la fin du XVIe au milieu du XIXe siècle), l’analyse croise les méthodes historiques traditionnelles avec les possibilités offertes par les outils informatiques contemporains tels que les SIG (géolocalisation et extraction de données qualitatives et quantitatives de cartes anciennes). L’analyse spatio-temporelle permet la reconstitution géohistorique des paysages de Soulac sur un temps long, en mettant en avant les dynamiques naturelles, les transformations importantes et les réponses apportées par les habitants. Ces derniers, d’abord impuissants et livrés à eux-mêmes par les autorités, tentent de s’adapter aux changements en adoptant plusieurs stratégies au cours du XVIIIe siècle. De la simple retenue des sables par des palissades à l’assèchement des marais doux et salés, ils essayent de répondre aux contraintes exercées sur eux par leur environnement. Mais ce sont les actions de l’État au début du XIXe siècle qui conditionnent la réussite des opérations de lutte et le début d’une nouvelle ère. Les dunes fixées par des pins et l’érosion enrayée par la construction d’ouvrages donnent naissance au paysage actuel de la pointe du Médoc. Plus qu’une simple monographie paroissiale, cette étude de cas permet de s’interroger sur notre environnement et les interactions que son exploitation et son peuplement influencent. Reconstruire sur un temps long les transformations permet une meilleure compréhension des risques et des phases de construction d’un espace géographique, et offre un recul historique permettant de mieux comprendre les événements récents. / Situated at the pointe du Medoc region, the parish of Soulac (modern day communes of Soulac-sur-Mer and Verdon-sur-Mer) is according to a medieval expression “at the end of the lands”. Squeezed between the Atlantic to the west, and the Gironde estuary to the east, the area includes a long coastline (14km of ocean coastline and 11km of estuary banks) which exposes it to phenomenon of natural origin linked to these maritime and fluvial-maritime movements. Since the end of the sixteenth century, the sand accumulated along the length of the coastline in the forms of dunes and carried by the wind onto habitations and cultures, causing the abandonment of the Soulac church and the early initial village in the mid eighteenth century. Simultaneously, the coastline was strongly attacked by erosion that spread in the middle of the Age of Enlightenment. To the east, the flat salt marshes were getting wider, reducing half their surface in less than a century. Finally, the low-lying areas of the parish are exposed to marine submersions, despite beginning with little frequency. This micro space, of 50km2, encompasses a good observation point in order to study the transformations of coastal land and the adaptations of populations to these changes. Taking support from important documentary resources (textual archives and cartographic maps) and continuous in the time (from the end of the 16th century to the middle of the 19th century), the analysis combines traditional historic methods with the possibilities offered by the contemporary computer tools, such as GIS (geolocation, extraction of qualitative data and quantitative old maps). The spatiotemporal analysis allows for the geohistoric reconstruction of the Soulac landscape over a long period, reflecting the natural dynamics, the important transformations and the responses from the inhabitants. The inhabitants, firstly made powerless by the authorities and had given up on themselves, have adapted to the changes by adopting many strategies throughout the course of the 18th century. From the simple control of the sand, using boundaries that dry up the soft, dirty marshes, they are trying to respond to the constraints forced upon them by their environment. However, the actions of the government at the beginning of the nineteenth century which allow for the success of the preventative actions and the start of a new era. The dunes fixed by pine trees and the erosion, stopped by the construction of structures, has given birth to the current landscape at the point of Medoc. More than a simple parish monograph, this case study allows us to ask questions about our environment and the affect that the interactions of cultivation and people have. Reconstructing over a long period of time the transformations offers a better understanding of the risks and the phases of construction of a geographical area offering a historical reviews which allows for a better understanding recent events.

Made available in DSpace on 2014-12-17T14:08:38Z (GMT). No. of bitstreams: 1 Janaina Medeiros Dantas Barbosa_DISSERT_01_35.pdf: 3284535 bytes, checksum: 7cd819680331f233db6c8299e7522b7b (MD5) Previous issue date: 2009-06-12 / Petr?leo Brasileiro SA - PETROBRAS / Continuous steam injection is one of heavy oil thermal recovery methods used in the Brazilian Northeast because of high occurrence of heavy oil reservoir. In this process, the oil into the reservoir is heated while reduces, substantially, its viscosity and improves the production. This work analyzed how the shaly sand layers influenced in the recovery. The studied models were synthetics, but the used reservoir data can be extrapolated to real situations of Potiguar Basin. The modeling was executed using the STARS - Steam Thermal and Advanced Process Reservoir Simulator - whose version was 2007.10. STARS is a tool of CMG Computer Modeling Group. The study was conducted in two stages, the first we analyzed the influence of reservoir parameters in the thermal process, so some of these were studied, including: horizontal permeability of the reservoir and the layer of shaly sand, ratio of horizontal permeability to vertical permeability, the influence of capillary pressure layer of shaly sand and as the location and dimensions of this heterogeneity can affect the productivity of oil. Among the parameters studied the horizontal permeability of the reservoir showed the most significant influence on the process followed by diversity. In the second stage three models were selected and studied some operational parameters such as injection rate, distance between wells, production time and completion intervals. Among the operating parameters studied the low rate and intermediate distances between wells showed the best recoveries / A inje??o cont?nua de vapor ? um dos m?todos t?rmicos de recupera??o de ?leos pesados utilizados no Nordeste Brasileiro, devido ? grande ocorr?ncia de reservat?rios contendo este tipo de ?leo. Este processo consiste em aquecer o ?leo existente no reservat?rio diminuindo substancialmente a sua viscosidade melhorando assim, a sua produ??o. Neste trabalho foi estudada qual a influ?ncia da presen?a de camadas de areia argilosas no reservat?rio para este tipo de recupera??o. Os modelos s?o sint?ticos, por?m com dados de reservat?rios que podem ser extrapolados para situa??es de aplica??es pr?ticas na Bacia Potiguar que apresenta reservat?rios com essa heterogeneidade. A modelagem foi implementada no simulador de recupera??o t?rmica STARS (Steam, Thermal, and Advanced Processes Reservoir Simulator) vers?o 2007.10 da CMG (Computer Modelling Group). O estudo foi realizado em duas etapas, na primeira foi analisada a influ?ncia dos par?metros de reservat?rio neste processo t?rmico, sendo assim, alguns desses foram estudados, dentre eles: permeabilidade horizontal do reservat?rio e da camada de areia argilosa, rela??o da permeabilidade horizontal com a permeabilidade vertical, influ?ncia da press?o capilar da camada de areia argilosa e como a localiza??o e as dimens?es dessa heterogeneidade podem afetar a produtividade de ?leo. Dentre os par?metros estudados a permeabilidade horizontal do reservat?rio foi o que apresentou maior influ?ncia significativa ao processo seguido da heterogeneidade. Na segunda etapa foram selecionados tr?s modelos e estudado alguns par?metros operacionais, tais como: vaz?o de inje??o, dist?ncia entre po?os, tempo de produ??o e intervalos de completa??o. Dentre os par?metros operacionais estudados as baixas vaz?es e as dist?ncias entre po?os intermedi?rias foram as que apresentaram as melhores recupera??es

Made available in DSpace on 2014-12-17T14:48:12Z (GMT). No. of bitstreams: 1 JohnGBG_DISSERT.pdf: 5632038 bytes, checksum: eabbd6743af14f648742650469c3d48f (MD5) Previous issue date: 2012-07-02 / A numerical study on the behavior of tied-back retaining walls in sand, using the finite element method (FEM) is presented. The analyses were performed using the software Plaxis 2D, and were focused on the development of horizontal displacements, horizontal stresses, shear forces and bending moments in the structure during the construction process. Emphasis was placed on the evaluation of wall embedment, tie-back horizontal spacing, wall thickness, and free anchor length on wall behavior. A representative soil profile of a specific region at the City of Natal, Brazil, was used in the numerical analyses. New facilities built on this region often include retaining structures of the same type studied herein. Soil behavior was modeled using the Mohr-Coulomb constitutive model, whereas the structural elements were modeled using the linear elastic model. Shear strength parameters of the soil layers were obtained from direct shear test results conducted with samples collected at the studied site. Deformation parameters were obtained from empirical correlations from SPT test results carried out on the studied site. The results of the numerical analyses revealed that the effect of wall embedment on the investigated parameters is virtually negligible. Conversely, the tie-back horizontal spacing plays an important role on the investigated parameters. The results also demonstrated that the wall thickness significantly affects the wall horizontal displacements, and the shear forces and bending moments within the retaining structure. However, wall thickness was not found to influence horizontal stresses in the structure / O presente trabalho apresenta um estudo num?rico atrav?s do m?todo dos elementos finitos (MEF) utilizando-se o aplicativo computacional Plaxis 2D, com o objetivo de verificar aspectos do comportamento de estruturas de conten??o atirantadas em areia. As an?lises foram dirigidas ao desenvolvimento dos deslocamentos horizontais, das tens?es horizontais e dos esfor?os internos (esfor?o cortante e momento fletor) durante o processo construtivo da estrutura. As simula??es num?ricas inclu?ram avalia??es da influ?ncia do comprimento da ficha, do espa?amento horizontal entre os tirantes, da espessura da parede e do comprimento do trecho livre. O perfil de solo utilizado nas simula??es num?ricas ? representativo de uma determinada regi?o da Cidade de Natal RN, na qual s?o constru?das com frequ?ncia conten??es do tipo analisado no presente trabalho. Utilizou-se o modelo constitutivo de Mohr-Coulomb para simular o comportamento do solo e o modelo el?stico linear para simular o comportamento dos elementos estruturais. Os par?metros de resist?ncia do solo foram determinados por meio de ensaios de cisalhamento direto e os par?metros de deformabilidade foram estimados atrav?s de correla??es emp?ricas obtidas de resultados de ensaios SPT executados na regi?o em estudo. Os resultados obtidos mostraram que varia??es no comprimento da ficha praticamente n?o influenciam o comportamento da estrutura, no ?mbito dos par?metros avaliados, ao passo que o espa?amento horizontal entre os tirantes apresenta forte influ?ncia sobre essas grandezas. Verificou-se tamb?m que a espessura da parede apresenta consider?vel influ?ncia sobre os deslocamentos horizontais e sobre os esfor?os internos e pouca influ?ncia sobre as tens?es horizontais

Made available in DSpace on 2014-12-17T14:48:13Z (GMT). No. of bitstreams: 1 FranciscoMGL_DISSERT.pdf: 2920200 bytes, checksum: c9c74c01a86db791fd1fef40b8b653c2 (MD5) Previous issue date: 2012-03-09 / Soil improved with the addition of cement have been utilized as an alternative to the construction of various types of geotechnical works, almost always present economic and environmental advantages. This paper presents a study on the usage of cement in the improvement of mechanical properties of sandy soils, characteristic of the region of Natal, collected from its dunes. This research was made in order to analyze the influence of cement content, voids, and also including water immersion and confining pressure. Samples molded from cement-soil mixtures were tested for unconfined compression tests and triaxial tests. The samples had the percentage of cement mixed in 2.5%, 5% and 10% by weight. The cement agent used was the Portland Cement of High Early strength(CPV-ARI), which promoted agility to the experimental procedure for presenting a rapid gain in strenght. The void ratio used ranged from 0.7 (more compact), 0,9 and 1,1(softer). The soil under study can be considered as pure sand. In general, it can be stated that the larger the amount of cement added to the sand studied is, the greater ultimate strength will be. Likewise, as more compact the soil is, the less void ratio and more resistant it will be present. The confining pressure tends to increase the resistance of the specimens. The cementing adopted grades showed that the use of different criteria for failure did not significantly alter the stress-strain parameters for the sand studied. The angle of friction values were found within the typical range of medium and compact sands. Cementing acted in the sand providing an intercepted cohesion which increased enhancing the potential cementation. In triaxial compression tests, the sand with void ratio is equal to 0.7 and showed the expected behavior for a compact sand while the stress-strain behavior of the same sand with the void ratio of 0.9 tended to be expected for the soft sand as well / Solos melhorados com adi??o de cimento t?m sido bastante utilizados como alternativa na constru??o de diversos tipos de obras geot?cnicas, quase sempre por apresentar vantagens econ?micas e ambientais. Este trabalho apresenta um estudo sobre a utiliza??o de cimento no melhoramento das propriedades mec?nicas de solos arenosos caracter?sticos da regi?o de Natal, coletados em dunas. Foi avaliada a influ?ncia do teor de cimento, do ?ndice de vazios, da inunda??o e da tens?o confinante. Corpos-de-prova moldados a partir de misturas de solo-cimento foram submetidos a ensaios de resist?ncia ? compress?o simples e ? compress?o triaxial convencional. Nas amostras as porcentagens de cimento foram variadas em 2,5%, 5% e 10% em peso. O agente cimentante utilizado foi o Cimento Portland de Alta resist?ncia inicial (CP-V ARI), que promoveu agilidade ao procedimento experimental por apresentar um processo de cura mais r?pido.Os ?ndices de vazios utilizados variaram de 0,7 (mais compacto), 0,9 e 1,1(mais fofo). O solo estudado pode ser considerado como uma areia pura. De uma forma geral, pode-se afirmar que quanto maior a quantidade de cimento adicionado ? areia estudada, maior a sua resist?ncia final. Da mesma forma, quanto mais compacto estiver esse solo, isto ?, quanto menor o ?ndice de vazios, mais resistente ele se apresentar?. A tens?o confinante tende a aumentar a resist?ncia dos corpos de prova. Nos graus de cimenta??o adotados, a utiliza??o de diferentes crit?rios de ruptura n?o alterou significativamente os par?metros tens?o-deforma??o para a areia estudada. Os valores de ?ngulo de atrito encontrados estavam dentro dos valores t?picos para areias m?dias e compactas. A cimenta??o agiu na areia de modo a proporcionar um intercepto de coes?o que aumentou com o incremento da cimenta??o. Nos ensaios de compress?o triaxial, a areia com ?ndice de vazios igual a 0,7 apresentou o comportamento esperado para uma areia compacta, enquanto o comportamento tens?o deforma??o da mesma areia com ?ndice de vazios de 0,9 tendeu ao esperado para a areia fofa

Made available in DSpace on 2014-12-17T14:48:16Z (GMT). No. of bitstreams: 1 ArthurGDA_DISSERT.pdf: 3193366 bytes, checksum: 6e05d0803e66a8ae37a24358be586be8 (MD5) Previous issue date: 2013-12-10 / An experimental study has been conducted to investigate the behavior of continuous flight auger (cfa) bored piles and metalic driven H-section piles under lateral loading in cohesionless soils. The piles were tested in two different areas at the same site. Both areas consisted of a 3-m thick compacted superficial fill of pure fine sand, underlain by layers of naturally occurring pure fine-thick sand. Fills are differentiated by the relative densities which were compressed, 45% e 70%, respectively. Each area received one identical pair of cfa piles and two identical pairs of H-piles. A static lateral loading test was performed in each pair of piles. In this work, the pile load test results are reported and interpreted. The horizontal coefficient of subgrade reaction was determined from the results of the loading tests and compared with values determined by correlations based on penetration resistance index of SPT tests (NSPT). p-y formulations describing the static behavior of the piles were applied to the problem under evaluation. Back Analyses were made through theoretical and experimental p-y curves for obtaining input parameters for the analytic models, among which the coefficient of horizontal reaction. The soil pile system horizontal loading at rupture was determined by the theoretical methods and the results were compared with the experimental results, checking its validity / Um estudo experimental foi realizado para investigar o comportamento de estacas escavadas h?lice cont?nua e estacas cravadas met?licas submetidas a carregamentos laterais em areia. As estacas foram ensaiadas em duas ?reas diferentes no mesmo local. Ambas as ?reas eram compostas por um aterro superficial de 3 m de espessura de areia fina, seguido de camadas naturais de areia fina a grossa. Os aterros diferenciam-se pela densidade relativa com que foram compactados, 45% e 70%, respectivamente. Cada ?rea recebeu um par id?ntico de estacas h?lice cont?nua e dois pares id?nticos de estacas met?licas com perfil H . Em cada par de estacas foi executada uma prova de carga est?tica. Neste trabalho, os resultados das provas de carga s?o apresentados e interpretados. O coeficiente de rea??o horizontal do solo foi determinado atrav?s dos resultados das provas de carga e comparado com valores obtidos a partir de correla??es baseadas no ?ndice de resist?ncia ? penetra??o do ensaio SPT (NSPT). Curvas p-y foram constru?das para prever o comportamento de estacas submetidas a carregamentos horizontais. Retro an?lises foram efetuadas atrav?s das curvas p-y te?ricas e experimentais para obten??o de par?metros de entrada para os modelos anal?ticos, dentre os quais o coeficiente de rea??o horizontal. A carga de ruptura do sistema solo estaca foi determinada atrav?s de m?todos te?ricos e os resultados foram comparados com os resultados experimentais, verificando sua validade

Made available in DSpace on 2014-10-09T12:28:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:15Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientador: Sérgio Luís de Carvalho / Banca: Edson Pereira Tangerino / Banca: Domingos Sávio Barbosa / Resumo: O aumento da contaminação de corpos hídricos por pesticidas juntamente com o melhor conhecimento das propriedades nocivas desses poluentes, têm aumentado o interesse na remoção destes compostos durante o tratamento de água potável. Sendo os pesticidas constituídos por moléculas biologicamente ativas e de difícil remoção durante o processo convencional de tratamento de água, o uso de filtros lentos de areia seguidos por filtros de carvão ativado biologicamente pode representar um sistema eficiente no tratamento de água. Considerando estes aspectos, o presente estudo teve como objetivo avaliar a eficiência da filtração lenta e da filtração utilizando carvão ativado biológico (CAB) na remoção do herbicida atrazina em escala de bancada e a composição fenotípica e genotípica dos microrganismos associados na degradação do herbicida. A remoção de atrazina atingiu uma remoção próxima de 100% nos efluentes dos filtros de areia e carvão. Foi verificada a presença de microrganismos (Bacillus e Salirhabdus) em ambos conjunto de filtros, podendo estes estarem ligados à degradação do herbicida da água. Os resultados deste estudo demonstraram eficiência na remoção de atrazina em níveis resguardados pela legislação sanitária, possibilitando o uso deste sistema na remoção do herbicida avaliado, assegurando a distribuição e consumo humano desta água. Além de avaliar a viabilidade do uso de filtros biológicos de carvão antecedidos por filtros lentos de areia na remoção de pesticidas, o presente trabalho poderá contribuir para realização de novas pesquisas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The increased contamination of watercourses by pesticides along with better knowledge of the harmful properties of these pollutants have increased interest in the removal of these compounds during treatment of drinking water. Since pesticides consisting of biologically active molecules and hard to remove during conventional water treatment, use of slow sand filters followed by biologically activated carbon filters may represent an efficient system for water treatment. Considering these aspects, this study aimed to evaluate the efficiency of slow sand filtration and biological filtration using activated carbon (BAC) in the removal of the herbicide atrazine in bench scale and phenotypic and genotypic composition of the microorganisms involved in degradation of the herbicide. The removal of atrazine reached a level close to 100% in effluent from sand and carbon filters compounds. We observed the presence of microorganisms (Bacillus and Salirhabdus) in both set of filters and they can be linked to degradation of the herbicide from water. The results showed removal efficiency of atrazine at levels controlled by the health legislation, enabling the use of this system in the removal of the herbicide evaluated, ensuring the distribution and consumption of water. Besides evaluating the feasibility of using biological filters charcoal preceded by slow sand filters for removal of pesticides, this study may contribute to new research on the technologies used in the treatment of drinking water contaminated by recalcitrant compounds. / Mestre

Cette thèse présente une étude expérimentale des mécanismes contrôlant la réponse macroscopique d’une interface sable-pieu sous sollicitations axiales monotones et cycliques. Une approche innovante associant la tomographie rayons X à des outils avancés d’analyses d’images en trois dimensions (3D) est utilisée dans le but d’extraire des informations à différentes échelles, notamment à l’échelle micro. L’analyse quantitative du comportement individuel des grains situés au voisinage du pieu fournit une collection de données 3D qui pourraient être utilisées pour la validation de modèles numériques ou théoriques.Une série de tests est réalisée sur un pieu instrumenté à pointe conique installé par vérinage monotone dans un échantillon dense de sable calcaire. Après l’installation, le pieu est soumis à un grand nombre de cycles axiaux contrôlés en déplacements (jusqu’à 2000 cycles), à contraintes constantes. Ces essais ont été conduits dans une mini chambre de calibration qui permet d’acquérir des tomographies rayons X à haute résolution après différentes étapes de chargement. Il est admis que le dispositif expérimental n’est pas représentatif des conditions d’essais sur pieux in-situ pour les raisons principales suivantes : le ratio entre le diamètre de la chambre le diamètre du pieu et le ratio entre le diamètre du pieu et la taille moyenne des grains sont bien inférieurs aux ratios recommandés dans la littérature afin de limiter les effets d’échelle. Par conséquent, les résultats obtenus dans ce travail ne peuvent et ne doivent pas être directement extrapolés pour le design de pieux réels. Cependant, un tel dispositif permet de reproduire qualitativement des tendances similaires à celles observées à l’échelle macro sur des essais à grande échelle et d’observer des mécanismes se déroulant à l’échelle micro.Les images 3D obtenues par reconstruction des tomographies rayons X sont utilisées afin d’identifier et de suivre l’évolution des grains individuels. Le champ cinématique complet en 3D est mesuré grâce à un code de corrélation d’images numériques 3D (DIC), « TomoWarp2 ». Des outils de traitement d’image sont également employés pour suivre les changements de porosité et la production de fines par broyage des grains à l’interface.Pendant la mise en place du pieu, plusieurs zones où les déplacements se concentrent sont identifiées. Une recirculation des grains le long du fût du pieu est mise en évidence. Globalement, le sable a un comportement dilatant à l’exception d’une fine couche (épaisseur d’environ 3 à 4·D50) autour du pieu où les fines sont produites. Pendant les cycles, la réponse macroscopique de l’interface montre une évolution en deux phases, avec une augmentation non négligeable de la résistance du fût dans la seconde phase. Pour ces deux phases, la mesure de la cinématique granulaire révèle un comportement du sol différent associé à une densification importante à l’interface. Dans la première phase, le sol se contracte radialement dans une zone de 4·D50 d’épaisseur. Ce phénomène est certainement dû au réarrangement granulaire mesuré par DIC. Dans la seconde phase, les grains de sables se déplacent difficilement et la densité à l’interface atteint un seuil pour lequel le frottement sur le pieu augmente de manière significative. / This doctoral work presents an experimental investigation into the mechanisms governing the macroscopic response of sand-pile interface during monotonic installation and subsequent axial cyclic loading. An innovative approach combining x-ray tomography and advanced image analysis tools is employed to extract information at different scales, including the micro-scale. A quantitative analysis of the behavior of individual sand grains in the vicinity of the pile offers valuable three-dimensional (3D) data set against which theoretical or numerical approaches could be tested.A series of tests is run on an instrumented close-ended conical model pile installed by monotonic jacking in a dense calcareous sand sample. Following the installation, the model pile is submitted to a large number of axial displacement-controlled loading cycles (a few thousands cycles) under constant normal stress. The tests are performed in a mini-calibration chamber that allows the acquisition of high resolution x-ray images at different stages of the loading. The chamber is admittedly not representative of field pile testing conditions for the main following reasons: the calibration chamber-to-pile diameter ratio and the sand particle-to-pile diameter ratio are far below the ratios recommended in the literature to limit scale effects on the interface response. Consequently, the results presented in this work can not, and should not, be directly extrapolated to field pile design. Yet, such a setup is able to reproduce qualitatively trends that are similar to those obtained at the macro-scale on large-scale experiments and allows the observation of full-field mechanisms taking place at the micro-scale.3D images resulting from the reconstruction of the x-ray scans are used to identify and follow the evolution of individual sand grains. Full-kinematics are measured thanks to a 3D Digital image Correlation (DIC) code, “TomoWarp2”. Image processing tools are also employed to measure local porosity changes and the production of fines by grain crushing at the interface.During pile installation, different zones where grains displacements concentrate are identified. A recirculation of the grains alongside the pile is also observed. Globally, the sand mass exhibits a dilative behavior except within a relatively thin layer (about 3 to 4·D50 thickness) around the model pile where grain crushing occurs. During subsequent loading cycles, the macroscopic response of sand-pile interface shows a two-phases evolution, with a non negligible increase of shaft resistance in the latter phase. For these two phases, the measurement of grain kinematics reveals a different behavior of the sand mass associated with a significant densification at the interface. In the first phase, the sand mass contracts radially within a region of thickness 4·D50. This mechanism is likely due to inter-granular rearrangement as measure by DIC. In the second phase, sand grains hardly move and the sand mass reaches a threshold density for which the friction on the shaft starts to increase substantially.

This thesis analyses the impact of granular aggregates with structures using experiments and numerical simulations. Original contributions include an insight into multiple factors affecting the loading and damage to the structures, along with study of numerical parameters important for realistic prediction of the interaction between the granular media and structures. It extends the current understanding related to such interactions, with an underlying motivation to guide strategies in order to reduce the structural damage. The response of structures impacted by granular media (sand or soil) is of significant research interest for many applications. One of the applications is for landmine explosions which causes ejection of soil from ground and damage to structures impacted by this ejected soil. Experimentation is done in a laboratory setting where the cylindrical sand slugs are generated at high speed using an impulse provided by a piston. This induces a velocity gradient along the slug, because of which the slug expands during the flight before impacting the target. Deformable as well as rigid flat targets are considered in two orientations relative to the incoming slug: perpendicular (i.e. normal orientation) and inclined at an angle of 45°. The targets are supported by force transducers to capture the loading from the slug. Simulations are performed using a combination of discrete particle and finite element schemes, which enables the analysis of the fully coupled interaction between the flowing granular media and the structure. A contact model involving multiple parameters is used for inter-particle and particle-target contact. Firstly, a numerical analysis is performed to characterise the temporal evolution of slugs and their impact on monolithic beams constrained at the ends. Out of all the parameters used for inter-particle contact definition in discrete particle method, only the contact stiffness is found to effect the velocity gradient in the slug before it impacts the target. Other factor influencing the gradient is the acceleration provided by the piston. A strong dependence of beam deflection on the stand-off distance is observed due to the velocity gradient in the slugs. As the second step, the effect of target surface properties on the transmitted momentum is analysed. Experiments are done by applying coatings of different hardness and roughness on the target surface impacted by sand slugs. For normally oriented targets, the transmitted momentum is observed to be insensitive to the change in surface coating. In contrast, for inclined targets, a significant influence of coatings is observed. Additionally, the momentum transmitted to the inclined targets is always less than that for normal targets. Numerical analysis of this surface effect reveals that assuming the slug particles to be spherical shape in simulations does not capture the particle/target interactions accurately and under-predicts the frictional loading on the target. Following this, a detailed numerical study is done to understand the effect of the shape of particles in the slug. Simple shaped non-spherical particles are constructed by combining spherical sub-particles. With increasing angularity of particles in the slug, the frictional loading on the target is shown to increase. This results in an increase of momentum transmitted to inclined targets. For normally oriented targets however, the particle shape does not affect the overall transmitted momentum, which is a behaviour similar to that observed when studying the effect of target surface properties. In addition, effect of fracture of particles in the slug is analysed by using beam connections between sub-particles that break during the impact with the target. If the fracture results in increasing particle angularity, the transmitted momentum increases, whereas the situation reverses if fracture results on more spherical shaped particles. Lastly, a strategy to reduce the loading on the targets is analysed by using sacrificial coating on the target surface. In experiments, this coating is placed on the rigid target surface using a lubricant at their interface. When impacted by the slug, this coating slides on the target surface, resulting in a reduction of frictional loading on the target. If the friction at the coating/target interface vanishes, the transmitted momentum approaches the theoretical minimum value. Simulations are used to first validate the experimental observations and then to extend the concept of sliding coatings using deformable targets. Both the transmitted momentum and deflections depended on the thickness of the target and coating. When a coating is used, the deflections increase due to reduction in target thickness. It is found that the best strategy to reduce the damage to the target is to use least possible thickness of the coating and minimise the friction at the interface between the coating and the target. The presented work examines many of the factors that affect the loading on the target impacted by granular slugs, in addition to characterising the expansion of slugs before the target impact. The analysed factors include those already known such as target stand-off distance, inclination and unveils others such as target surface properties and granular properties. The numerical analysis discloses important parameters and shows the effect of particle shape, highlighting the shortcomings of widely used spherical particle assumption in the numerical studies. A strategy using a sacrificial coating to reduce damage to the target is also analysed.