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Nous étudions le drainage des mousses de suspension granulaire. Nos paramètres de contrôle sont : la fraction en gaz, la taille des bulles, celle des particules et la fraction volumique de celles-ci dans la phase interstitielle. En premier lieu, nous mesurons la proportion de liquide et de particules retenus dans le réseau de la mousse en fonction des paramètres cités précédemment. Ces mesures réalisées une fois le drainage terminé apportent des éléments de compréhension indispensables à la description des vitesses de drainage. Nous montrons également que certaines combinaisons de nos paramètres d'étude conduisent au blocage du système gaz, liquide, solide. Dans un second temps, nous avons identifié différents régimes de cinétique de drainage, nous montrons qu'ils sont contrôlés par deux paramètres : (i) le rapport lambda de la taille des particules et de la taille des constrictions du réseau, (ii) la fraction en particules dans la phase interstitielle phi. Le point clé pour comprendre ces régimes est le piégeage des particules dans la mousse qui peut avoir deux origines : (i) par piégeage collectif (jamming) qui peut survenir pour des fractions étonnamment basses à cause de la géométrie du réseau interstitiel, (ii) la capture individuelle des particules par la mousse lorsque leur taille devient supérieure à celle des constrictions du réseau interstitiel. Des particules encore plus grosses sont exclues du réseau et participent à une remontée de la vitesse de drainage, faisant apparaître un minimum pour le régime correspondant à la capture individuelle. La fraction granulaire de la phase interstitielle est aussi essentielle, le drainage pouvant être stoppé pour des fractions suffisamment élevées lorsque lambda est judicieusement choisi. Ce travail propose des pistes prometteuses pour la stabilité des matériaux triphasiques / We study the drainage of granular suspensions foams. Our control parameters are the gas fraction, the bubble size, the particles size and the interstitial particle fraction. First, we measure the proportion of liquid and particles retained in the foam network as function of the above mentioned parameters. These measurements are performed when the drainage is over, they are essential for the description of drainage velocity. We show that certain combinations of our study parameters lead to the jamming of the three-phase system : gas, liquid, solid. Secondly, we highlight different regimes of drainage velocity, we show that is controlled by two parameters : (i) lambda, the ratio of the particle size and constriction size, (ii) the fraction of particles in the interstitial network : phi. The key to understand these regimes is the trapping of particles in the foam : (i) the jamming, which may occur for surprisingly low fractions due to the geometry of the pore network, (ii) the particles captured by the foam network when they become larger than the constrictions network. Finally, larger particles excluded from the network increase the drainage velocity, as a consequence the minimum for the velocity corresponds to the individual capture. The granular fraction of the suspension in the foam network is the other key parameter. Especially, the drainage can be stopped for sufficiently high fractions for certain values of lambda. This work offers promising outlook for the stability of three-phase materials

Les variations latérales d'exhumation de l'Himalaya sont peu documentées, notamment dans la partie est. Dans ce mémoire, l'évolution de la chaîne himalayenne est étudiée à partir de trois coupes réalisées dans le bassin d'avant-pays mio-pliocène où l'âge des sédiments a été déterminé par magnétostratigraphie. La contribution des différents domaines sources ainsi que leur exhumation ont été définies par des analyses géochimiques (εNd) et de thermochronologie détritique (apatite et zircon). Dans la partie orientale, nos observations suggèrent que les surrections concomitantes du plateau du Shillong et du prisme Indo-Birman ont repoussé le Brahmapoutre vers 7 Ma le long du front de la chaîne himalayenne. Les résultats des analyses de thermochronologie détritique soulignent une dynamique et des vitesses d'exhumation (1,7 km/Ma) semblables à celles de la partie centrale de la chaîne, en dépit de précipitations plus intenses et malgré la présence du plateau du Shillong au sud qui pourrait avoir absorbé une partie du raccourcissement tectonique. En revanche, l'installation d'une exhumation contrastée semble légèrement plus tardive que dans la partie centrale et ouest de la chaîne. Enfin, ces travaux suggèrent qu'au niveau de la syntaxe orientale il a existé un temps de latence d'au moins 3 Ma avant l'installation d'une rétroaction tectonique-érosion dans le massif du Namche Barwa liée à l'installation d'un drainage transverse à la chaîne. Au sein même de la partie centrale de la chaîne des variations latérales d'exhumation ont été mises en évidence, notamment, la mise en place au Népal occidental d'une exhumation rapide, reconnue dès 13 Ma, alors que celle-ci semble plus tardive dans la partie orientale du Népal. L'étude de la coupe occidentale a montré que le réseau de drainage du paléo-Indus est stable dans le bassin d'avant-pays depuis le Miocène moyen. En revanche, la proportion de matériaux provenant de l'Himalaya augmente à partir du Pliocène et ceci de manière généralisée le long de la partie ouest de la chaîne, suggérant un changement drastique des conditions d'exhumation de la chaîne. L'exhumation de la chaîne himalayenne apparaît donc comme étant segmentée latéralement. La mise en place d'une exhumation contrastée et diachrone le long de la chaîne ne semble donc pas liée à d'éventuels changements climatiques qui auraient affecté la chaîne de manière globale. La dynamique d'exhumation du prisme himalayen observée actuellement semble donc liée à des hétérogénéités de la croûte indienne, qui contrôlerait la mise en place des structures profondes de la chaîne. / From west to east along the Himalayan range, exhumation rates are variable and remain poorly constrained for the most part, especially in the eastern part of the mountain belt. To better understand their variability and to determine the influence of climatic and tectonic control, this thesis investigates the evolution of the range thanks to samples collected from three sections located in the eastern, central and western parts of the Mio-Pliocene Himalayan foreland basin. In these sections, sediment depositional ages were determined using magnetostratigraphy. Sediment provenance and contribution of the main litho-tectonic source-rock units were identified using geochemical analyses (Nd), while exhumation rates were determined with detrital apatite and zircon thermochronology. In the eastern part of the Himalaya, our results from the Kameng section in Arunachal Pradesh suggest that the surface uplift of both the Shillong Plateau and the Indo-Burman range have pushed the Brahmaputra River to the north, in front of the Himalayan range at about 7 Ma. Miocene-Pliocene exhumation rates inferred from detrital thermochronology are on the order of 1.7 km/Myr for the fastest exhuming areas, which is close to the rates reported for the central part of the range. Therefore, the distribution of precipitation, as well as the Shillong Plateau uplift which may have modified the convergence rate between the Indian and Eurasian plates, seem to have minor influence on the exhumation of eastern Himalaya. However, the onset of contrasting exhumation seems to have begun somewhat earlier than in the western and central parts of the range. In addition, our results highlight a 3 Myr time-lag between the installation of the Brahmaputra as a trunk river in the eastern syntaxes, and the onset of a fast exhumation there. Within the central part of the Himalaya, our work along the Muksar section in eastern Nepal documents lateral variations in exhumation rates, as western Nepal has been exhuming rapidly since 13 Ma, whereas the onset of fast exhumation seems to have occured later in eastern Nepal. Our results from the Chinji section in Pakistan, in western Himalaya, suggest that the Indus drainage network in the foreland basin has been stable since the middle Miocene. However, the Himalayan source contribution has been increasing since the Pliocene all along the western part of the range, and this suggests that a drastic change in the exhumation dynamics of the range occurred at that time. The Himalayan exhumation seems to be divided into independent segments along the range. The lateral variability in exhumation rates and timing of changes in exhumation rates do not seem to be linked to climatic change, which should produce a global response of the range. The exhumation dynamics is more likely to be linked to the tectonics structuring the wedge, possibly controlled by the crustal heterogeneity within the Indian plate.

Les déchets sulfurés issus de l’extraction des minerais métalliques génèrent des drainages miniers acides (DMA) contenant des éléments toxiques tels que l’arsenic. Les procédés de traitement passifs basés sur l’oxydation bactérienne du fer et de l’arsenic, en favorisant la précipitation de ces éléments sous une forme stable, pourraient représenter une solution efficace et économique pour traiter cette pollution. Dans ce contexte, l’objectif général de cette thèse était de mieux comprendre les facteurs environnementaux et opérationnels qui contrôlent l’efficacité d’élimination de l’arsenic. Une approche en pilote à flux continu a été mise en oeuvre afin de se rapprocher des conditions réelles d’un traitement. L’étude a été conduite d’abord à l’échelle d’un bioréacteur de paillasse en conditions contrôlées (température, lumière, débit, temps de séjour et hauteur d’eau), puis dans un dispositif de taille supérieure, fonctionnant de manière totalement passive et in situ. Ces dispositifs ont été alimentés avec de l’eau d’un DMA riche en arsenic, issue de l’ancien site minier de Carnoulès, dans le Gard. Les caractéristiques de l’eau et des bioprécipités au sein de ces pilotes, en particulier le rédox du fer et de l’arsenic, ont été suivis dans différentes conditions environnementales et d’opération par des méthodes de spéciation liquide et solide (HPLC-ICP-MS, EXAFS, XANES), des analyses minéralogiques (DRX) et des analyses microbiologiques (ARISA, séquençage haut débit du gène de l'ARNr 16S, quantification du gène aioA). Les résultats issus des expériences en laboratoire ont mis en évidence l’effet de différents paramètres opérationnels (hauteur d’eau, temps de rétention hydraulique, et présence/absence d’une pellicule flottante) sur les performances du traitement, ainsi que sur la microbiologie et la minéralogie des bioprécipités formés. Le dispositif de terrain a permis de tester les performances du procédé dans des conditions environnementales fluctuantes (variabilité de la physico-chimie de l’eau d’entrée et de la température) et d’acquérir des connaissances nouvelles sur l’évolution des bioprécipités au cours de six mois de traitement. Les connaissances acquises dans cette thèse pourront servir de base à la conception d’une étape d’élimination de l’arsenic dans les processus de traitement des DMA. / Acid mine drainage (AMD) are produced by sulfuric tailings from mining of metal ores. They are characterized by high contents of toxic elements like arsenic. One efficient and economical solution for the treatment of As in these tailings could be the use of a passive method based on iron and arsenic bacterial oxidation, and the subsequent precipitation of these elements in a stable form. In this context, the objective of this PhD thesis was to better understand the environmental and operational factors controlling the efficiency of As removal processes. A continuous-flow pilot approach was implemented in order to better reproduce the real treatment conditions. This study was first performed in a bench-scale bioreactor with controlled conditions (temperature, light, flow, residence time and water height). Then, it was performed in a field-scale bioreactor installed in situ, reproducing a passive treatment in real conditions. These devices were fed with As-rich AMD waters from the ancient mine of Carnoulès (Gard, France). Water and bioprecipitate properties were monitored in both devices, specially the redox speciation of iron and arsenic. This monitoring was held for different environmental and operational conditions. Iron and arsenic speciation in liquid and solid phases was measured by different analytical techniques such as HPLC-ICP-MS, EXAFS and XANES. Mineral identification was made by XRD analysis, while microbiological characterization was made by ARISA, high-throughput sequencing of 16S rRNA gene, and aioA gene quantification. Results from the lab-scale experiments evidenced the effects of the different operational parameters (water height, hydraulic retention time and the presence/absence of a floating film) on the treatment performance, as well as on the microbiology and mineralogy of the produced bioprecipitates. The field device was used to test the treatment performance under fluctuating environmental conditions (variability of the physico-chemistry of the feed water and of the temperature) and to gain new knowledge about the evolution of the bioprecipitates during six months of treatment. All the knowledge acquired in this PhD thesis could serve as a basis for the design of an arsenic removal stage in DMA treatment processes.

L’évaporation d’une solution saline en milieu poreux intervient dans diverses situations comme lors de l’injection de dioxyde de carbone dans des aquifères salins ou dans des processus de dégradation des monuments ou de la végétation. Un aspect clé est la cristallisation des sels dissous à la surface ou au sein du milieu poreux résultant de l’évaporation de la solution. Dans la première partie de ce manuscrit, nous étudions le séchage d’un milieu poreux modèle initialement saturé par une solution aqueuse de chlorure de sodium pour différentes tailles moyennes de pores et différents flux d’évaporation. Ceci nous permet d’obtenir une caractérisation des cristaux formés en surface (efflorescence) en fonction de ces paramètres. Nous nous intéressons ensuite tout particulièrement au cas où l’efflorescence forme une croûte d’apparence compacte. Un aspect intrigant est que cette croûte ne bloque pas complètement l’évaporation. Le taux d’évaporation est réduit d’un ordre de grandeur environ. Une modélisation de la croissance de la croûte est développée pour expliquer ce phénomène. Dans une deuxième partie du manuscrit, nous nous intéressons au phénomène relié à la croissance d’un efflorescence “rampante” à la surface d’un substrat solide, dans notre cas la surface externe d’un tube capillaire droit dont une extrémité est plongée dans une solution de chlorure de sodium. Les lois de croissance de ce phénomène sont caractérisées à partir du suivi temporel par double pesée de la masse d’eau évaporée et de la masse de sel qui précipite ainsi que de la géométrie de l’enveloppe externe de la couche de sel recouvrant progressivement le capillaire. Ici encore, l’analyse du phénomène de croissance est confortée par une modélisation numérique simple. Un aspect important de ce travail est le recours à des techniques de visualisations modernes (microtomographie à rayons X, microscopie électronique à balayage, scanner de surface à lumière structurée) pour obtenir autant d’informations que possible sur la structure des efflorescences et les mécanismes de croissance mis en jeu dans ces expériences. / Evaporation of saline solution in porous media occurs in various situations such as injection of carbon dioxide in saline aquifers or in degradation processes on monuments or on vegetation. A key aspect is the crystallization of dissolved salts on the surface or in the porous medium resulting from the evaporation of the solution. In the first part of this manuscript, we study the drying of model porous media model initially saturated with an aqueous solution of sodium chloride, for different average pore sizes and different evaporation fluxes. This allows us to obtain a characterization of the salt crystals formed on the surface (efflorescence) depending on these parameters. We are particularly interested in the case when the efflorescence forms an apparently compact crust. An intriguing aspect is that the crust does not completely block the evaporation. The evaporation rate is in fact reduced by an order of ten. To explain this phenomenon, a model of the growth of the crust is developed. In a second part of the manuscript, we are interested in the growth of a salt efflorescence by “creeping” on a solid substrate, here the outer surface of a straight capillary tube, with one end immersed in a sodium chloride solution. The growth laws of this phenomenon are characterized by weighing both the mass of water evaporated and the mass of salt that precipitates, as well as recording the geometry of the outer casing of the salt layer gradually covering the capillary. Again, the analysis of this growth phenomenon is supported by a simple numerical model. An important aspect of this work is the use of up-todate visuablisation techniques (such as X-ray micro-tomography, scanning electron microscopy and structuredlight surface scanning) to get as much as possible additional information on the efflorescence structure and growth mechanism at play in these experiments.

Os diversos e indesejáveis problemas associados à ocorrência de inundações e de picos rápidos de cheia são comuns nos centros urbanos brasileiros, sendo agravados em decorrência da crescente impermeabilização das superfícies alavancada pelo crescimento das cidades. Uma das alternativas para reduzir esses problemas consiste no uso de pavimentações drenantes, que possibilitem a infiltração e colaborem com o retardo do escoamento das águas pluviais. Dentre as opções disponíveis, vem atraindo atenção, nos últimos anos, o denominado concreto permeável, material fabricado com uma composição granulométrica selecionada (sem agregado miúdo e com partículas de dimensões similares), de forma a gerar uma estrutura de grandes poros conectados, que permite uma rápida percolação de fluidos pelo seu interior, em grandes quantidades. Levando em consideração os diferentes desafios associados à drenagem urbana, as pesquisas no LEME voltaram-se para a investigação de uma nova possibilidade de utilização do concreto permeável, como material componente dos próprios elementos dos sistemas urbanos de drenagem pluvial. Sabe-se que um dos principais problemas de funcionamento desses sistemas consiste na obstaculização de suas entradas por materiais diversos em conjunto com a diminuição da área de passagem de água nas galerias pelo acúmulo de material nas mesmas, gerando entupimento parcial ou total. Nesses casos, o uso de concreto permeável pode viabilizar a passagem de elevados fluxos, ao mesmo tempo em que constitui uma barreira à passagem de detritos e um filtro natural das águas, potencialmente evitando o ingresso de materiais, lixo e partículas sólidas no interior das galerias do sistema de drenagem. Buscando contribuir para a avaliação da ideia, o presente trabalho foi concebido tendo como foco o estudo da utilização do concreto permeável para fabricação de elementos tipo placa, em substituição às grelhas utilizadas atualmente. Para orientar tecnicamente o estudo, tomou-se como referência o Caderno de Encargos do Departamento de Esgotos Pluviais (DEP) da cidade de Porto Alegre, que estabelece as características dessas grelhas. Após um estudo preliminar para ajuste do traço e caracterização básica do concreto permeável, foram moldados seis protótipos de placas com um traço 1:4 (cimento:areia), com dimensões similares às grelhas do DEP, confeccionadas em concreto permeável. As placas foram testadas quanto à capacidade de flexão e à permeabilidade (sendo esses últimos efetuados em corpos de prova extraídos das placas). Para fins de comparação, foi ensaiada, também, uma grelha real fabricada e disponibilizada pelo DEP. Adicionalmente, foram criados, no LEME, dispositivos especiais para simular os efeitos de chuva e de passagem de água, carreando material em suspensão, para avaliar o desempenho em termos de colmatação desses elementos. Os resultados dos ensaios de resistência mecânica e de permeabilidade indicaram que os novos elementos apresentam desempenho superior às grelhas convencionais, indicando que os estudos na direção da produção de elementos drenantes em concreto permeável são promissores e devem ser continuados. Os resultados do teste de colmatação indicam, no entanto, que procedimentos de manutenção e limpeza podem ser necessários se material pulverulento bloquear os poros do concreto permeável. / Many undesirable problems associated with the occurrence of floods and rapid flood peaks are common in Brazilian urban centers and are intensified due to the increase of waterproofing of surfaces caused by the growth of cities. An alternative to mitigate these problems is the use of draining pavements that allow infiltration and collaborate with the delay of storm water runoff. Among the available options, pervious concrete has been attracting attention in recent years. This is a special concrete made with selected particle size distribution (without coarse aggregate and particles of similar dimensions) to generate a structure containing large connected pores, which would allow a fast and large percolation of fluids trough the material. Taking into account the different challenges associated with urban drainage, the research group at LEME has been investigating a new possibility for the use of pervious concrete as a constituent material of urban stormwater drainage systems. It is well known that the major problem that affects this kind of systems is the obstruction of the openings by different materials, in addition to the decrease of water flow in the galleries because of the accumulation of material inside them, causing partial or total loss of flow capacity. The use of pervious concrete can enable the passage of high flow rates, while constituting a barrier to the passage of debris and a natural water filter, preventing the entry of potentially granular material and solid waste particles inside the galleries of the drainage system. Seeking to contribute to the evaluation of this idea, the present work was designed focusing on the study of the use of pervious concrete for the manufacture of plate elements, which could be used to replace the grilles that are currently in use in sewers. In order to guide the study, the requirements of the Rain Sewage Department (Departamento de Esgotos Pluviais - DEP) from Porto Alegre were taken as a reference. After a preliminary study made to adjust and characterize the mix of pervious concrete to be used, six plates prototypes were fabricated using a 1:4 (cement:sand) proportion, with similar dimensions to the DEP grilles. These were then tested to check flexural capacity and permeability (of specimens cored from the plates). Also, using special devices created at LEME, the effects of rain and the passage of water carrying fine material in suspension were simulated, and the performance in terms of clogging of these elements was roughly assessed. For comparison, a conventional grille currently made by DEP was also tested. The results from the mechanical strength and permeability tests indicated that the pervious plates had superior performance when compared to the conventional grilles, indicating that studies toward the production of drainage elements in pervious concrete are promising and should be continued. The results from the clogging test however indicate that cleaning strategies may be necessary on the long run if fine material accumulates in the pores of the pervious concrete.

Os diversos e indesejáveis problemas associados à ocorrência de inundações e de picos rápidos de cheia são comuns nos centros urbanos brasileiros, sendo agravados em decorrência da crescente impermeabilização das superfícies alavancada pelo crescimento das cidades. Uma das alternativas para reduzir esses problemas consiste no uso de pavimentações drenantes, que possibilitem a infiltração e colaborem com o retardo do escoamento das águas pluviais. Dentre as opções disponíveis, vem atraindo atenção, nos últimos anos, o denominado concreto permeável, material fabricado com uma composição granulométrica selecionada (sem agregado miúdo e com partículas de dimensões similares), de forma a gerar uma estrutura de grandes poros conectados, que permite uma rápida percolação de fluidos pelo seu interior, em grandes quantidades. Levando em consideração os diferentes desafios associados à drenagem urbana, as pesquisas no LEME voltaram-se para a investigação de uma nova possibilidade de utilização do concreto permeável, como material componente dos próprios elementos dos sistemas urbanos de drenagem pluvial. Sabe-se que um dos principais problemas de funcionamento desses sistemas consiste na obstaculização de suas entradas por materiais diversos em conjunto com a diminuição da área de passagem de água nas galerias pelo acúmulo de material nas mesmas, gerando entupimento parcial ou total. Nesses casos, o uso de concreto permeável pode viabilizar a passagem de elevados fluxos, ao mesmo tempo em que constitui uma barreira à passagem de detritos e um filtro natural das águas, potencialmente evitando o ingresso de materiais, lixo e partículas sólidas no interior das galerias do sistema de drenagem. Buscando contribuir para a avaliação da ideia, o presente trabalho foi concebido tendo como foco o estudo da utilização do concreto permeável para fabricação de elementos tipo placa, em substituição às grelhas utilizadas atualmente. Para orientar tecnicamente o estudo, tomou-se como referência o Caderno de Encargos do Departamento de Esgotos Pluviais (DEP) da cidade de Porto Alegre, que estabelece as características dessas grelhas. Após um estudo preliminar para ajuste do traço e caracterização básica do concreto permeável, foram moldados seis protótipos de placas com um traço 1:4 (cimento:areia), com dimensões similares às grelhas do DEP, confeccionadas em concreto permeável. As placas foram testadas quanto à capacidade de flexão e à permeabilidade (sendo esses últimos efetuados em corpos de prova extraídos das placas). Para fins de comparação, foi ensaiada, também, uma grelha real fabricada e disponibilizada pelo DEP. Adicionalmente, foram criados, no LEME, dispositivos especiais para simular os efeitos de chuva e de passagem de água, carreando material em suspensão, para avaliar o desempenho em termos de colmatação desses elementos. Os resultados dos ensaios de resistência mecânica e de permeabilidade indicaram que os novos elementos apresentam desempenho superior às grelhas convencionais, indicando que os estudos na direção da produção de elementos drenantes em concreto permeável são promissores e devem ser continuados. Os resultados do teste de colmatação indicam, no entanto, que procedimentos de manutenção e limpeza podem ser necessários se material pulverulento bloquear os poros do concreto permeável. / Many undesirable problems associated with the occurrence of floods and rapid flood peaks are common in Brazilian urban centers and are intensified due to the increase of waterproofing of surfaces caused by the growth of cities. An alternative to mitigate these problems is the use of draining pavements that allow infiltration and collaborate with the delay of storm water runoff. Among the available options, pervious concrete has been attracting attention in recent years. This is a special concrete made with selected particle size distribution (without coarse aggregate and particles of similar dimensions) to generate a structure containing large connected pores, which would allow a fast and large percolation of fluids trough the material. Taking into account the different challenges associated with urban drainage, the research group at LEME has been investigating a new possibility for the use of pervious concrete as a constituent material of urban stormwater drainage systems. It is well known that the major problem that affects this kind of systems is the obstruction of the openings by different materials, in addition to the decrease of water flow in the galleries because of the accumulation of material inside them, causing partial or total loss of flow capacity. The use of pervious concrete can enable the passage of high flow rates, while constituting a barrier to the passage of debris and a natural water filter, preventing the entry of potentially granular material and solid waste particles inside the galleries of the drainage system. Seeking to contribute to the evaluation of this idea, the present work was designed focusing on the study of the use of pervious concrete for the manufacture of plate elements, which could be used to replace the grilles that are currently in use in sewers. In order to guide the study, the requirements of the Rain Sewage Department (Departamento de Esgotos Pluviais - DEP) from Porto Alegre were taken as a reference. After a preliminary study made to adjust and characterize the mix of pervious concrete to be used, six plates prototypes were fabricated using a 1:4 (cement:sand) proportion, with similar dimensions to the DEP grilles. These were then tested to check flexural capacity and permeability (of specimens cored from the plates). Also, using special devices created at LEME, the effects of rain and the passage of water carrying fine material in suspension were simulated, and the performance in terms of clogging of these elements was roughly assessed. For comparison, a conventional grille currently made by DEP was also tested. The results from the mechanical strength and permeability tests indicated that the pervious plates had superior performance when compared to the conventional grilles, indicating that studies toward the production of drainage elements in pervious concrete are promising and should be continued. The results from the clogging test however indicate that cleaning strategies may be necessary on the long run if fine material accumulates in the pores of the pervious concrete.

Esta dissertação apresenta o uso de drenagem profunda para estabilização de encostas, detalhando os sistemas existentes e suas aplicações. São relatados alguns casos de encostas estabilizadas através da drenagem profunda, tanto no Brasil como no exterior. Apresenta-se também um estudo de caso da obra de estabilização da encosta na qual está implantado o viaduto denominado VA-19, na Rodovia dos Imigrantes no Estado de São Paulo, em que foi utilizado túnel de drenagem como solução. É feita a análise da eficiência do túnel de drenagem para o rebaixamento do lençol freático e conseqüente estabilização da encosta. / This dissertation presents the use of deep drainage for slope stabilization, detailing the existent systems and their applications. Some cases of slope stabilized through deep drainage are reported. It is also presented a study of case of the slope stabilization which affected the overpass called VA-19, in the Imigrantes Highway, in the State of São Paulo which used drainage tunnel as a solution. The analysis of the drainage tunnel efficiency in the water table lowering and consequent slope stabilization.

Os diversos e indesejáveis problemas associados à ocorrência de inundações e de picos rápidos de cheia são comuns nos centros urbanos brasileiros, sendo agravados em decorrência da crescente impermeabilização das superfícies alavancada pelo crescimento das cidades. Uma das alternativas para reduzir esses problemas consiste no uso de pavimentações drenantes, que possibilitem a infiltração e colaborem com o retardo do escoamento das águas pluviais. Dentre as opções disponíveis, vem atraindo atenção, nos últimos anos, o denominado concreto permeável, material fabricado com uma composição granulométrica selecionada (sem agregado miúdo e com partículas de dimensões similares), de forma a gerar uma estrutura de grandes poros conectados, que permite uma rápida percolação de fluidos pelo seu interior, em grandes quantidades. Levando em consideração os diferentes desafios associados à drenagem urbana, as pesquisas no LEME voltaram-se para a investigação de uma nova possibilidade de utilização do concreto permeável, como material componente dos próprios elementos dos sistemas urbanos de drenagem pluvial. Sabe-se que um dos principais problemas de funcionamento desses sistemas consiste na obstaculização de suas entradas por materiais diversos em conjunto com a diminuição da área de passagem de água nas galerias pelo acúmulo de material nas mesmas, gerando entupimento parcial ou total. Nesses casos, o uso de concreto permeável pode viabilizar a passagem de elevados fluxos, ao mesmo tempo em que constitui uma barreira à passagem de detritos e um filtro natural das águas, potencialmente evitando o ingresso de materiais, lixo e partículas sólidas no interior das galerias do sistema de drenagem. Buscando contribuir para a avaliação da ideia, o presente trabalho foi concebido tendo como foco o estudo da utilização do concreto permeável para fabricação de elementos tipo placa, em substituição às grelhas utilizadas atualmente. Para orientar tecnicamente o estudo, tomou-se como referência o Caderno de Encargos do Departamento de Esgotos Pluviais (DEP) da cidade de Porto Alegre, que estabelece as características dessas grelhas. Após um estudo preliminar para ajuste do traço e caracterização básica do concreto permeável, foram moldados seis protótipos de placas com um traço 1:4 (cimento:areia), com dimensões similares às grelhas do DEP, confeccionadas em concreto permeável. As placas foram testadas quanto à capacidade de flexão e à permeabilidade (sendo esses últimos efetuados em corpos de prova extraídos das placas). Para fins de comparação, foi ensaiada, também, uma grelha real fabricada e disponibilizada pelo DEP. Adicionalmente, foram criados, no LEME, dispositivos especiais para simular os efeitos de chuva e de passagem de água, carreando material em suspensão, para avaliar o desempenho em termos de colmatação desses elementos. Os resultados dos ensaios de resistência mecânica e de permeabilidade indicaram que os novos elementos apresentam desempenho superior às grelhas convencionais, indicando que os estudos na direção da produção de elementos drenantes em concreto permeável são promissores e devem ser continuados. Os resultados do teste de colmatação indicam, no entanto, que procedimentos de manutenção e limpeza podem ser necessários se material pulverulento bloquear os poros do concreto permeável. / Many undesirable problems associated with the occurrence of floods and rapid flood peaks are common in Brazilian urban centers and are intensified due to the increase of waterproofing of surfaces caused by the growth of cities. An alternative to mitigate these problems is the use of draining pavements that allow infiltration and collaborate with the delay of storm water runoff. Among the available options, pervious concrete has been attracting attention in recent years. This is a special concrete made with selected particle size distribution (without coarse aggregate and particles of similar dimensions) to generate a structure containing large connected pores, which would allow a fast and large percolation of fluids trough the material. Taking into account the different challenges associated with urban drainage, the research group at LEME has been investigating a new possibility for the use of pervious concrete as a constituent material of urban stormwater drainage systems. It is well known that the major problem that affects this kind of systems is the obstruction of the openings by different materials, in addition to the decrease of water flow in the galleries because of the accumulation of material inside them, causing partial or total loss of flow capacity. The use of pervious concrete can enable the passage of high flow rates, while constituting a barrier to the passage of debris and a natural water filter, preventing the entry of potentially granular material and solid waste particles inside the galleries of the drainage system. Seeking to contribute to the evaluation of this idea, the present work was designed focusing on the study of the use of pervious concrete for the manufacture of plate elements, which could be used to replace the grilles that are currently in use in sewers. In order to guide the study, the requirements of the Rain Sewage Department (Departamento de Esgotos Pluviais - DEP) from Porto Alegre were taken as a reference. After a preliminary study made to adjust and characterize the mix of pervious concrete to be used, six plates prototypes were fabricated using a 1:4 (cement:sand) proportion, with similar dimensions to the DEP grilles. These were then tested to check flexural capacity and permeability (of specimens cored from the plates). Also, using special devices created at LEME, the effects of rain and the passage of water carrying fine material in suspension were simulated, and the performance in terms of clogging of these elements was roughly assessed. For comparison, a conventional grille currently made by DEP was also tested. The results from the mechanical strength and permeability tests indicated that the pervious plates had superior performance when compared to the conventional grilles, indicating that studies toward the production of drainage elements in pervious concrete are promising and should be continued. The results from the clogging test however indicate that cleaning strategies may be necessary on the long run if fine material accumulates in the pores of the pervious concrete.