A capillary barrier develops and restricts water flow when two porous materials with dissimilar pore structures (e.g., a coarse-grained soil overlain by a fine-grained soil) are in contact with one another. This is due to a difference in the unsaturated hydraulic conductivity of the two materials at a given suction. Geotextiles are utilized in a variety of civil engineering applications and have a pore structure similar to that of a coarse-grained soil. This can be problematic in unsaturated soil as the capillary barrier caused by the geotextile may instigate undesirable moisture buildup in the overlying soil and undermine any benefit provided by the geotextile. Various versions of a new geotextile have been manufactured to help dissipate a capillary barrier by "wicking" or laterally draining excess moisture away from the soil. Additionally, nonwoven blends of the unique wicking fiber combined with standard polymeric fibers are tested to assess their ability to minimize the development of a geotextile capillary barrier and not cause additional moisture accumulation in the first place. The unsaturated properties of both woven and nonwoven configurations of these wicking geotextiles were investigated as part of a comprehensive an experimental testing program. The testing program includes small soil column infiltration tests to assess geotextile capillary barrier performance with moisture monitored by time domain reflectometers and capacitance probes. Also, modified hanging column tests were conducted to define the hydraulic properties of the geotextiles in the form of water retention curves. Finally, a microscopy study, involving both optical and scanning electron microscopes, was conducted to observe the wicking behavior of the geotextiles at a micro-scale level. Test results illustrate the enhanced lateral drainage and reduced moisture accumulation of the wicking geotextiles when compared to regular geotextiles. Additionally, the woven version of the wicking geotextile has the potential to perform the functions of separation, filtration, protection, reinforcement, and drainage. All of these functions in a single geosynthetic product could lead to significant cost savings compared to the use of separate products to perform each one of the various functions. / text

Geotextiles are often incorporated in engineered structures—including landfill liners and covers, earthen dams, retaining walls, and roads—to perform the separation, filtration, and/or drainage functions. Under unsaturated conditions typical of such structures, a capillary break may form at the interface between soil and geotextile. If the break is unplanned, the resulting build-up of moisture may be detrimental to the structure. Conversely, properly designed geotextile capillary barriers have the potential for many positive applications. Design information, including a complete framework for analysis and an accepted laboratory characterization approach, is lacking. The primary objectives of this study were to investigate geotextile capillary barrier performance with a simple laboratory model and propose a framework for complete analysis of a geotextile capillary barrier life cycle. Soil columns were designed to allow the formation and breakthrough of a geotextile capillary barrier to be observed. Materials used in the columns were obtained from a capillary barrier system currently under construction at the Rocky Mountain Arsenal in Denver, CO. Hydraulic characterization of the soil and geotextile were performed in the lab. Eleven column tests were completed for this study—soil compaction and applied flow rate were varied to investigate their effect on capillary barrier response. Analysis was approached within a proposed framework covering each stage of a capillary barrier life cycle. While there was considerable scatter in the test results, important insight was gained. The geotextile capillary barrier performed consistently. Conditions near the interface at breakthrough were similar between tests, regardless of soil compaction or applied flow rate, and were predicted adequately with the laboratory characterization. Storage capacity of the capillary barrier decreased with increasing relative compaction. A framework for analysis, from which the entire capillary barrier response may be modeled, was developed. Application of this model allowed for identification of weaknesses and recommendations for future work. / text

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第22678号 / 地環博第199号 / 新制||地環||39(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 勝見 武, 教授 三村 衛, 准教授 高井 敦史 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

This study presents the climatic effects (rainfall and evaporation) on the stability of reinforced soil walls constructed with nonwoven geotextiles reinforcements using numerical modeling. The evaluation of the climatic effects was organized in two steps: (1) numerical modeling of the infiltration compared to a laboratory full-scale model of a nonwoven reinforced soil wall and; (2) a numerical investigation of a hypothetical geosynthetic-reinforced soil wall subjected to climatic changes including precipitation and evaporation, for a period of 2 years. The numerical modeling of infiltration into the full-scale model was conducted using two representative hydraulic parameters of backfill soil (suction and volumetric moisture content). The infiltration modeling of the laboratory reinforced structure was conducted to provide better understanding around the hydraulic behavior and water path into regions not measured by instrumentation during laboratory tests. Numerical calibration was conducted in order to capture the capillary break developed at soil-geotextile interfaces, including the anchorage of the reinforcements in the wrap-around facing. As a second step of this study, a hypothetical reinforced soil wall constructed with nonwoven geotextile was modeled using the same hydraulic properties of soil and geotextile used in the previously described numerical modeling. The climatic changes were simulated considering the water balance at ground surface. The climatic effects on the reinforced soil wall were assessed by the use of soil suction changes and consequent influences on the factors of safety over 2 years of operation. Results from numerical simulation of infiltration into the laboratory model indicated that water breakthrough did not occur uniformly along the length of the geotextile. In addition, numerical infiltration into the laboratory model showed that the water path into the reinforced zone is influenced by the anchorage of the reinforcement in the wrap-around facing. The results of the climatic variations in the hypothetical structure showed that approximately 50% of potential evaporation and total rainfall effectively evaporates and infiltrates. Also, the results revealed that the capillary barrier did not generate significant surface runoff and did not reduce the effective infiltration in the reinforced zone. On the other hand, water was observed to advance faster outside of the reinforced zone than inside of the reinforced zone because of the capillary barrier. Additionally, simulations showed that soil inside of the reinforced zone never recovered its initial suction value after first wetting because the capillary barrier restricted evaporation. Results also revealed that increases in global factor of safety, after first wetting of the geotextile reinforced soil wall, occurred because of the increases in soil suction of the first reinforced layer. Lastly, cumulative precipitation during successive days of rainfall showed some correlation to changes in global factor of safety. / Este estudo apresenta os efeitos das variações climáticas (chuva e evaporação) em muros de solo reforçado com geotêxtil não tecido através de analises numéricas. A avaliação dos efeitos climáticos foi dividida em duas fases: (1) calibração numérica da infiltração em um protótipo de laboratório de muro reforçado com geotêxtil não tecido e; (2) extrapolação dos resultados de infiltração para uma estrutura hipotética incluindo as variações climáticas de chuva e evaporação por um período de 2 anos. A calibração numérica foi realizada por meio de duas variáveis (sucção e umidade volumétrica) medidas durante a infiltração no protótipo. Estudos numéricos do processo de infiltração foram conduzidos para melhor entender o comportamento hidráulico da infiltração em regiões que não foram monitoradas durante a infiltração no protótipo. A calibração numérica foi conduzida com o objetivo de capturar o efeito da barreira capilar na interface solo-geotêxtil não tecido, incluindo a ancoragem do reforço próximo a face envelopada. A partir dos resultados da calibração, um muro hipotético reforçado com geotêxtil não tecido foi modelado sob condições climáticas reais (chuva e evaporação), e seu desempenho foi avaliado através das variações de sucção e do fator de segurança ao longo de 2 anos. As variações climáticas foram modeladas considerando o balanço de hídrico na superfície do solo. Os resultados da calibração numérica do modelo de laboratório indicaram que a barreira capilar na interface solo-reforço rompeu de forma não uniforme ao longo do geotêxtil não tecido. Além disso, a avaliação da infiltração mostrou que o fluxo de água tem sua direção afetada pela ancoragem do reforço próximo a face. Os resultados das variações climáticas na estrutura hipotética mostraram que aproximadamente 50% da evaporação potencial e da chuva total efetivamente evapora e infiltra. Além disso, os resultados revelaram que a formação de barreira capilar, e consequente retardo na infiltração, não gerou escoamento superficial significativo e não reduziu o volume de água efetivamente infiltrado na zona reforçada. Ademais, as variações de sucção observadas na zona reforçada se mostraram diretamente ligadas aos dias consecutivos de chuva. Por outro lado, observou-se que a frente de umedecimento avançou mais rápido fora da zona reforçada do que dentro da zona reforçada devido à barreira capilar. As simulações mostraram que o solo dentro da zona reforçada nunca recuperou seu valor inicial de sucção após o primeiro umedecimento porque a barreira capilar restringiu a evaporação. Os resultados também revelaram que o aumento no fator global de segurança, após o primeiro umedecimento do muro reforçado com geotêxtil, ocorreu devido ao aumento da sucção do solo da primeira camada reforçada. Por fim, a precipitação acumulada durante dias consecutivos de chuva mostrou correlação com as mudanças no fator de segurança.

Identifying principles of water movement in the shallow subsurface is crucial for adequate process-based hydrological models. Hillslopes are the essential interface for water movement in catchments. The shallow subsurface on slopes typically consists of different layers with varying characteristics. The aim of this study was to draw conclusions about the infiltration behaviour, to identify water flow pathways and derive some general interpretations for the validity of the water movement on a hillslope with periglacial slope deposits (cover beds), where the layers differ in their sedimentological and hydrological properties. Especially the described varying influence of the basal layer (LB) as an impeding layer on the one hand and as a remarkable pathway for rapid subsurface stormflow on the other. We used a time lapse 3-D electrical resistivity tomography (ERT) approach combined with punctual hydrometric data to trace the spreading and the progression of an irrigation plume in layered slope deposits during two irrigation experiments. This multi-technical approach enables us to connect the high spatial resolution of the 3-D ERT with the high temporal resolution of the hydrometric devices. Infiltration through the uppermost layer was dominated by preferential flow, whereas the water flow in the deeper layers was mainly matrix flow. Subsurface stormflow due to impeding characteristic of the underlying layer occurs in form of organic layer interflow and at the interface to the first basal layer (LB1). However, the main driving factor for subsurface stormflow is the formation of a capillary barrier at the interface to the second basal layer (LB2). The capillary barrier prevents water from entering the deeper layer under unsaturated conditions and diverts the seepage water according to the slope inclination. With higher saturation, the capillary barrier breaks down and water reaches the highly conductive deeper layer. This highlights the importance of the capillary barrier effect for the prevention or activation of different flow pathways under variable hydrological conditions.

Identifying principles of water movement in the shallow subsurface is crucial for adequate process-based hydrological models. Hillslopes are the essential interface for water movement in catchments. The shallow subsurface on slopes typically consists of different layers with varying characteristics. The aim of this study was to draw conclusions about the infiltration behaviour, to identify water flow pathways and derive some general interpretations for the validity of the water movement on a hillslope with periglacial slope deposits (cover beds), where the layers differ in their sedimentological and hydrological properties. Especially the described varying influence of the basal layer (LB) as an impeding layer on the one hand and as a remarkable pathway for rapid subsurface stormflow on the other. We used a time lapse 3-D electrical resistivity tomography (ERT) approach combined with punctual hydrometric data to trace the spreading and the progression of an irrigation plume in layered slope deposits during two irrigation experiments. This multi-technical approach enables us to connect the high spatial resolution of the 3-D ERT with the high temporal resolution of the hydrometric devices. Infiltration through the uppermost layer was dominated by preferential flow, whereas the water flow in the deeper layers was mainly matrix flow. Subsurface stormflow due to impeding characteristic of the underlying layer occurs in form of organic layer interflow and at the interface to the first basal layer (LB1). However, the main driving factor for subsurface stormflow is the formation of a capillary barrier at the interface to the second basal layer (LB2). The capillary barrier prevents water from entering the deeper layer under unsaturated conditions and diverts the seepage water according to the slope inclination. With higher saturation, the capillary barrier breaks down and water reaches the highly conductive deeper layer. This highlights the importance of the capillary barrier effect for the prevention or activation of different flow pathways under variable hydrological conditions.

The objectives of this research were to 1) measure the extent to which water vapor movement results in water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement in freezing base materials; 3) determine if the corresponding changes in water content are sufficient to cause frost heave during winter; 4) determine if the corresponding changes in water content are sufficient to cause reductions in stiffness during spring; 5) evaluate relationships between selected material properties, freezing conditions, and the occurrence and impact of water vapor movement; and 6) numerically simulate heat and water movement in selected pavement design scenarios. The research involved extensive laboratory and field testing, statistical analyses, and numerical modeling. The results of the laboratory testing, which included gradations, Atterberg limits, soil classifications, specific gravity and absorption values, electrical conductivity values, moisture-density relationships, soil-water characteristic curves, moisture-stiffness curves, hydraulic conductivity values, and frost susceptibility assessments, were used to characterize each material and enable subsequent statistical analyses. Testing of both treated and untreated materials enabled investigation of a wide variety of material properties. The results of the field testing, which included temperature, moisture content, water potential, elevation, and stiffness data over time, provided the basis for comparing pavement sections with and without capillary barriers and established the framework for numerical modeling. In a pavement section with a capillary barrier underlying the base layer, water vapor movement from the subgrade through the capillary barrier may be expected to increase the water content of the base layer by 1 to 3 percent during a typical winter season in northern Utah for base materials similar to those studied in this research. During winter, cold temperatures create an ideal environment for water vapor to travel upward from the warm subgrade soil below the frost line, through the capillary barrier, and into the base material. Soil stabilization can lead to increased or decreased amounts of water vapor movement in freezing base materials depending on the properties of the stabilized soil, which may be affected by gradation, mineralogy, and stabilizer type and concentration. Accumulation of water from long-term water vapor movement into frost-susceptible base materials underlain by a capillary barrier can lead to frost heave of the base layer as it approaches saturation, as water available in the layer can be redistributed upwards to create ice lenses upon freezing. However, the incremental increase in total water content that may occur exclusively from water vapor movement during a single winter season in northern Utah would not be expected to cause measurable increases in thaw weakening of the base layer during spring. Because water in a base layer overlying a capillary barrier cannot drain until nearly reaching positive pore pressures, the base layer will remain indefinitely saturated or nearly saturated as demonstrated in this research. For materials similar to those studied in this research, potentially important material properties related to the occurrence of water vapor movement during freezing include dry density, percent of material finer than the No. 200 sieve, percent of material finer than 0.02 mm, apparent specific gravity, absorption, initial water content, porosity, degree of saturation, hydraulic conductivity, and electrical conductivity. The rate at which water vapor movement occurs is also dependent on the thermal gradient within the given material, where higher thermal gradients are associated with higher amounts of water vapor movement. The numerical modeling supported the field observations that the capillary barrier effectively trapped moisture in the overlying base material, causing it to remain saturated or nearly saturated throughout the monitoring period. Only non-frost-susceptible aggregate base materials should be specified for use in cold climates in conjunction with capillary barriers, and the base material in this case should be assumed to remain in a saturated or nearly saturated condition during the entire service life of the pavement. Further study is recommended on water vapor movement in freezing aggregate base materials.

L’hétérogénéité de la zone non saturée joue un rôle important dans le transfert d’eau et de soluté car elle accentue à la fois le développement des zones de stockage temporelles et les écoulements préférentiels. Par conséquent, la validation des modèles prédictifs nécessite le développement des outils expérimentaux spécifiques afin d’observer et de quantifier les mécanismes de transport impliqués dans un système non saturé hétérogène. Cette thèse vise à étudier l’effet combiné de la vitesse d’infiltration, de la barrière capillaire et l’angle de la pente d’interface entre deux matériaux sur les processus de l’écoulement de l’eau et du transport de soluté dans un modèle physique, le lysimètre de laboratoire 1x1x1.6 m3, nommé LUGH (Lysimeter for Urban Groundwater Hydrology) et un modèle numérique 3D de ce lysimètre. Le lysimètre LUGH est rempli par un sable fin et un mélange bimodal (50 % sable fin et 50 % gravier) en deux configurations: un profil uniforme de matériau bimodal ou un profil avec deux couches avec une pente de 14o. Ces agencements figurent l’hétérogénéité structurale et texturale observée sur un des sites expérimentaux de l’OTHU (Observatoire de Terrain en Hydrologie Urbaine) : le bassin d’infiltration d’eaux pluviales Django Reinhardt géré par la ville de Lyon (France). Le lysimètre est alimenté en eau et avec un traceur inerte (bromure de potassium, KBr) sur une partie de la surface par un système d’arrosage automatique. Les effluents ont été recueillis dans quinze sorties différentes en bas du lysimètre. La forte hétérogénéité des flux des sorties et des courbes de percée souligne la mise en place des écoulements préférentiels résultant à la fois de l’effet de barrière capillaire et de l’effet de fond du lysimètre. A partir des résultats expérimentaux, la modélisation numérique à l’aide de logiciel COMSOL MultiphysicsTM a permis de mieux comprendre les mécanismes responsables de ces transferts hétérogènes. Lorsque le modèle numérique validé, un test de sensibilité a été conduit pour étudier les effets de la vitesse d’infiltration et de la pente de l’interface sur l’écoulement. Les résultats montrent que la diminution de la vitesse d’infiltration ou l’augmentation de la pente de l’interface favorisent le développement des écoulements préférentiels. Notre étude a donné également des renseignements pertinents sur le couplage entre les processus hydrodynamiques et le transfert des solutés dans les sols non saturés hétérogènes en soulignant le rôle de la géométrie des interfaces ainsi que celui des conditions aux limites comme des facteurs clés pour la quantification des écoulements préférentiels. / The heterogeneity of the unsaturated zone plays an important role in the water and solutes transfer as it accentuates both the development of stagnant zones for water and preferential flow. Therefore, the validation of predictive models requires the development of specific experimental tools to observe and quantify the transport mechanisms involved in a heterogeneous unsaturated system. The aim of this thesis is to describe the combined effect of infiltration, capillary barrier and sloping layered soil on both flow and solute transport processes in a large physical model (1x1x1.6 m3) called LUGH (Lysimeter for Urban Groundwater Hydrology) and a 3D numerical flow model. Sand and a soil composed of a bimodal sand-gravel mixture were placed in the lysimeter represent one of the commun structural and textural elements of the heterogeneity observed in the vadose zone under an infiltration basin of Lyon (France). The soil was compacted in two configurations: a uniform profile and a profile with two layers having a slope of 14°. Water and an inert tracer (KBr) were injected from the top of the lysimeter using a specific water sprinkler system and collected at 15 different outlets at the bottom. The 15 breakthrough curves obtained presented high heterogeneity, emphasising the establishment of a preferential flow resulting from both capillary barrier and soil layer dip effects. Numerical modelling led to better understanding of the mechanisms responsible for these heterogeneous transfers and it was also used to perform a sensitivity analysis of the effects of water velocity (water and solute flux fed by the sprinkler) and the slope interface. The results show that decreasing velocity and increasing the slope of the interface can lead to the development of preferential flows. In addition, the offset of the centre of gravity of the flow distribution at the output increases linearly as a function of the slope angle of the layered soil. This paper allows coupling the hydrodynamic approach with the transfer of pollutants in unsaturated heterogeneous soil and highlighting preferential flow by flow modeling.

Après exposition par inhalation, les nanoparticules (NPs) peuvent atteindre les alvéoles pulmonaires, se retrouver au niveau de la barrière alvéolo-capillaire (BAC), et induire une toxicité locale et / ou franchir cette barrière pour se retrouver dans la circulation sanguine. Dans ce contexte, l’objectif de ce travail a été de développer des modèles de co-cultures in vitro simples à mettre en œuvre (utilisation de lignées cellulaires humaines), pour étudier les effets des NPs au niveau de la BAC. Dans un premier temps, des co-cultures de cellules épithéliales alvéolaires ou de phénotype proche (lignées A549 ou NCI-H441), et de macrophages (lignée THP-1), ont permis l’étude des effets pro-inflammatoires des NPs de SiO2 et de TiO2. Avec ces modèles nous avons montré l’importance de la coopération cellulaire mise en jeu lors des processus inflammatoires liés aux NPs, mais aussi le rôle du ratio cellulaire employé dans ces réponses. Dans un second temps, des co-cultures tridimensionnelles en chambres bicamérales associant des macrophages (lignée THP-1), des cellules épithéliales bronchiques (lignée Calu-3), et des cellules endothéliales pulmonaires microvasculaires (lignée HPMEC-ST1.6R), ont permis l’étude de l’impact de NPs fluorescentes de polystyrène sur l’intégrité de la BAC, et leur passage à travers cette barrière. Les cellules épithéliales Calu-3 permettent d’établir une barrière de qualité mais la membrane microporeuse servant de support aux cellules doit être optimisée pour ne pas être un frein au passage des NPs. Ce travail montre qu’un seul modèle ne permet pas d’étudier de façon optimale à la fois la toxicité et la translocation des NPs, et qu’une approche adaptée doit être envisagée en fonction du paramètre que l’on souhaite étudier. / After inhalation, nanoparticles (NPs) can reach the alveoli and the alveolo-capillary barrier (ACB), and consequently induce local toxicity and / or cross this barrier to reach the bloodstream. In this context, the aim of this work was to develop co-culture in vitro models simple to implement (using human cell lines), to study effects of NPs on the ACB. In a first time, pro-inflammatory effects of SiO2 and TiO2 NPs were studied on co-cultures of alveolar epithelial cells (A549 and NCI-H441 cell lines), and macrophages (THP-1 cell line). We demonstrated the importance of cell cooperation during inflammatory processes caused by these NPs, and the role of the cellular ratio in these inflammatory responses. In a second time, effects of fluorescent polystyrene NPs on the ACB integrity, and their translocation were studied on three-dimensional co-cultures in bicameral chambers involving macrophages (THP-1 cell line), bronchial epithelial cells (Calu-3 cell line), and micro-vascular pulmonary endothelial cells (HPMEC ST1.6R cell line). The use of Calu-3 has provided a good barrier, but further investigations on microporous membranes are still needed to not interfere with NPs translocation. Altogether, these results show that a tailored approach should be considered in order to study toxicity or translocation of NPs.