This thesis thrives to promote community health and wellbeing through smart design, celebrating culture(s), and offering efficacious and real-world solutions to mitigate certain challenges arising from the imminent threat of climate change and the gradual depletion of our planet's natural resources. The projected building harnesses naturel forces, minimizes energy consumption, and uses natural/passive strategies like thermal mass and natural ventilation. Interior spaces enjoy an abundance of Natural lighting, biophilic attributes, and thera-serlized or uninterrupted views. It generates electrical energy due to adequate solar power and clear skies, especially in hot and arid climates like the proposed location of the project in Tuba City, AZ. In my proposal of a sustainable, community-focused, wellness center, this project will attempt to embrace diversity, celebrate the Navajos heritage through incorporating their belief system and culture into the genius Loci of the place, which will have a long-term healing effect on patients during their journey of recovery. The Navajo nation is a native American reservation and a self-governing community located in the southwest of the US between four states (UT, AZ, NM, CO). Since it's an Underserved, marginalized, and medically under-resourced community, the Navajo Nation was prone to COVID-19 onslaught in 2020, which resulted in substantial number of cases compared to other US states. / Master of Architecture / In Dec 2020, the World witnessed the first case of Coronavirus disease or COVID-19 in Wuhan, China. The disease has since spread rapidly worldwide, leading to an ongoing pandemic. Like many countries across the globe, the health system in the United States of America has to grabble with this deadly virus by inducing measures such as mask mandates and lockdowns in many US states. Unfortunately, and due to economic and social disparities, COVID-19 pandemic has brought injustice and inequity to the forefront of public health. Some communities were hit hard due to lack of emergency response, the availability of health professionals, and healthcare infrastructure. Tuba city, which is the Diné or the Navajo nation second-largest community in Coconino County, AZ, was majorly hit with COVID-19 resulting in a significant number of cases compared to other US cities. This project is a critical component of an emergency preparedness matrix that can firstly; help absorb the shock of such outbreaks by providing primary and outpatient services. Secondly; it offers community-focused and wellness service that can empower underserved, under-resourced and valuable communities like the Navajo Nation. This project is unique due to its inherited and embedded characteristics of bringing the Navajo tradition into the spirit of the building, by celebrating their culture making it a key component in a patent's healing process.

The purpose of this study was to extract galvanized steel wire reinforcement coupons from mechanically stabilized earth (MSE) walls along I-15 and determine the rate of corrosion that has taken place since Phase I, which was conducted by Gerber and Billings (2010). The galvanized steel reinforcement analyzed in this study has been in place for 19 to 20 years at the time of extraction. A total of 85 coupons were extracted and laboratory analysis was performed to determine the thickness of remaining zinc galvanization on each coupon. Soil samples were obtained from each one-stage wall extraction location to determine moisture content for correlation with corrosion. After laboratory testing was performed, the measured zinc coating thickness was compared to that determined in Phase I. An average corrosion rate of approximately 0.032 oz/ft²/year has occurred since Phase I. According to the AASHTO (2017) design corrosion rate of 0.35 oz/ft²/year for the first two years and 0.09 oz/ft²/year until the depletion of the zinc, the zinc coating would have been completely depleted after 16 years. Based on the results of laboratory testing, the initial galvanization coating was likely greater than the specified thickness of 2.0 oz/ft² (86 μm). The zinc galvanization is corroding at a slower rate than the AASHTO design rate. The AASHTO design rate for depletion of zinc coating and subsequent corrosion of the steel reinforcement is conservative for the corrosion conditions present in the MSE wall reinforcement coupons tested. The integrity of the steel reinforcement that is currently in place is not likely to be compromised by corrosion.

A Mechanically Stabilized Earth (MSE) wall is a vertical grade separation that uses earth reinforcement extending laterally from the wall to take advantage of earth pressure to reduce the required design strength of the wall. MSE wall systems are often prefabricated to reduce construction time, thus improving constructability when compared with conventionally cast-in-place reinforced wall systems. However, there is a lack of knowledge for predicting the service-life of MSE retaining wall systems when recycled backfill materials such as Recycled Asphalt Pavement (RAP) and Crushed Concrete (CC) are used instead of Conventional Fill Material (CFM). The specific knowledge missing is how these recycled materials, when used as backfill in MSE wall systems, affects the corrosion rate of the reinforcing strips. This work addresses this knowledge gap by providing recommendations for MSE wall systems backfilled with CC or RAP, and provides a guide to predict the service-life based on corrosion rate test data obtained from embedding steel and galvanized-steel earth reinforcing strips embedded in MSE wall systems backfilled with CC, RAP, and CFM. Experimental data from samples emulating MSE wall systems with steel and galvanized-steel reinforcing strips embedded in CC and RAP were compared to samples with strips embedded in CFM. The results of the testing provide data and methodologies that may, depending on the environmental exposure conditions, justify the use of RAP and CC for the construction of MSE walls. If these backfill materials are obtained from the construction site, this could provide a significant cost savings during construction.

Cette thèse étudie le comportement de remblais en sol renforcé lors du passage de trains par simulation numérique. Il s'agit de déterminer si les trains à grande vitesse ont un impact particulier sur ce type d'ouvrage. Après un état de l'art des remblais en sol renforcé et de la modélisation numérique de problèmes ferroviaires, les résultats du chargement harmonique d'un remblai expérimental en Terre Armée sont analysés. Ils montrent que les valeurs des tractions dans les armatures, des contraintes et déplacements dans le massif dépendent de la fréquence de la sollicitation, c'est-à-dire de la vitesse de passage du train. On construit un modèle 3D aux éléments finis pour reproduire cette expérience. Il permet de retrouver les valeurs expérimentales avec une bonne précision, en mettant en avant l'importance du choix des lois de comportement du sol, du parement et des armatures. Ce modèle avec ses paramètres est alors utilisé pour discuter du comportement local de l'interface armature/remblai au cours d'un chargement harmonique en régime établi. Le confinement varie beaucoup le long des armatures supérieures au cours du chargement dynamique, tandis que les tractions sont peu affectées par le chargement dynamique. Cependant, malgré ces variations au cours du temps, la stabilité de l'interface reste peu affectée par rapport au cas d'un chargement statique. Un second modèle a été développé pour représenter un remblai de taille plus importante, en utilisant la modélisation multiphasique et en utilisant un repère mobile pour prendre en compte le déplacement du train. Les aspects théoriques et l'implémentation de ce modèle dans le code CESAR-LCPC sont détaillés. On l'utilise pour effectuer une étude tri-dimensionnelle d'un remblai renforcé. Elle met en évidence la faible influence de la vitesse de la charge sur la réponse de l'ouvrage, dans le cas d'un remblai rigide ayant des caractéristiques tirées du remblai expérimental. Dans le cas d'un remblai moins rigide, la vitesse d'un TGV peut s'approcher de la vitesse des ondes de cisaillement dans le massif avec des conséquences significatives au sein de la structure. Finalement, les valeurs expérimentales et les deux modèles numériques développés présentent les mêmes tendances : l'effet dynamique du passage du train a pour conséquence une augmentation des déplacements et une variation du confinement des armatures, tandis que les niveaux de traction sont peu affectés par la charge, ce qui nous incite à conclure que la vitesse du train n'est pas significativement pénalisante sur la stabilité des remblais pour les paramètres issus de l'analyse du remblai expérimental. Toutefois, ces résultats dépendent fortement de la géométrie de la structure, de la façon de modéliser le train, des lois de comportement et des valeurs des paramètres retenus pour le sol, le parement et l'interface sol/armature / This study focuses on the numerical modeling of the Mechanically Stabilized Earth (MSE) walls behavior under High Speed Train (HST) loading. First, the state of the art in reinforced earth as well as in railway dynamics modeling is analyzed. Then we present results coming from the testing of a one-scale reinforced embankment submitted to harmonic loading. They indicate that tensile forces in reinforcements, stresses and displacements depend on loading frequency which is related to train speed. One proposes a 3D Finite Element Model (FEM) in order to numerically reproduce this experimentation. The numerical results fit reasonably well with the experimental ones, highlighting the great importance of the choice of the constitutive law for the soil, reinforcement and facing. The same model is used to locally investigate the soil/reinforcement interface behaviour during a harmonic loading in steady-state. The confining pressure presents significant variations along the reinforcement strip during the dynamic loading while tensile forces are less affected by the load. Nevertheless, the global interface stability remains acceptable compared to a static load. A second numerical model is proposed, which represents a bigger embankment. The multiphase model is used to represent the reinforced soil and moving coordinates are used to take into account the moving train. Theoretical developments of this model and its implementation into CESAR-LCPC FEM code are detailed. The results indicate that the train speed does not play a big role in the overall response of the structure, in the case of a stiff reinforcement comparable to the experimental one. If the embankment is weaker, the HST speed may be close to shear waves speed within the soil, which has significant consequences into the structure, particularly on the stability of the soil/reinforcement interface. Globally the experimental results and those coming from both numerical models present the same trends: the dynamic effect coming from the train passing leads to the in-crease of displacements and confining pressure close to the highest strips, while tensile forces are less affected by the load. This leads us to the conclusion that the train speed does not have a significant effect on the stability of MSE walls, at least for embankments having similar parameters than the experimental one. However these results strongly depend on the embankment geometry, the way to model the train and the parameters and constitutive laws chosen for the soil, the soil/reinforcement interface and the facing

Rammed earth is a technique of forming in-situ structural wall elements using rigid formwork. Advantages of rammed earth walls include flexibility in plan form, scope for adjusting strength and wall thickness, variety of textural finishes, lower embodied carbon and energy, etc. There is a growing interest in the construction of rammed earth buildings in the recent past. Well focused comprehensive studies in understanding the structural performance of rammed earth structures are scanty. Clear-cut guidelines on selecting soil grading and soil characteristics, assessing strength of rammed earth walls, density strength relationships, limits on shrinkage, standardised testing procedures, behaviour of rammed earth walls under in-plane and out of plane loads, etc are the areas needing attention. The thesis attempts to address some of these aspects of cement stabilized rammed earth for structural walls. Brief history and developments in rammed earth construction with illustrations of rammed earth buildings are presented. A review of the literature on rammed earth has been provided under two categories: (a) Unstabilised or pure rammed earth and (b) stabilised rammed earth. Review of the existing codes of practice on rammed earth has also been included. Summary of the literature on rammed earth along with points requiring attention for further R&D are discussed. Objectives and scope of the thesis are listed. The thesis deals with an extensive experimentation on cement stabilised rammed earth (CSRE) specimens and walls. Four varieties of specimens (cylindrical, prisms, wallettes and full scale walls) were used in the experiments. A natural soil and its reconstituted variants were used in the experimental work. Details of the experimental programme, characteristics of raw materials used in the experimental investigations, methods of preparing different types of specimens and their testing procedures are discussed in detail. Influence of soil grading, cement content, moulding water content, density and delayed compaction on compaction characteristics and strength of cement stabilised soil mixes were examined. Five different soil gradings with clay content ranging between 9 and 31.6% and three cement contents (5%, 8% and 12%) were considered. Effect of delayed compaction (time lag) on compaction characteristics and compressive strength of cement stabilised soils was examined by monitoring the results up to 10 hours of time lag. Influence of moulding water content and density on compressive strength and water absorption of cement stabilised soils was examined considering for a range of densities and water contents. The results indicate that (a) there is a considerable difference between dry and wet compressive strength of CSRE prisms, and the strength decreases as the moisture content at the time of testing increases, (b) wet strength is less than that of dry strength and the ratio between wet to dry strength depends upon the clay fraction of soil mix and cement content, (c) saturated moisture content depends upon the cement content and the clay content of the soil mix, (d) optimum clay percentage yielding maximum compressive strength is about 16%, (e) compressive strength of compacted cement stabilised soil increases with increase in density irrespective of cement content and moulding moisture content, and the strength increases by 300% for 20% increase in density from 15.70 kN/m3, (f) compressive strength of rammed earth is one - third higher than that of rammed earth brick masonry and (g) density decreases with increase in time lag and there is 50% decrease in strength with 10 hour time lag. Stress-strain relationships and elastic properties of cement stabilised rammed earth are essential for the analysis of CSRE structural elements and understanding the structural behaviour of CSRE walls. Influence of soil composition, density, cement content and moisture on stress-strain relationships of CSRE was studied. Three different densities (15.7 – 19.62 kN/m3) and three cement percentages (5%, 8% and 12% by weight) were considered for CSRE. Stress-strain characteristics of CSRE and rammed earth brick masonry were compared. The results reveal that (a) in dry condition the post peak response shows considerable deformation (strain hardening type behaviour) beyond the peak stress and ultimate strain values at failure (dry state) are as high as 3.5%, which is unusual for brittle materials, (b) modulus for CSRE increases with increase in density as well as cement content and there is 1 to 3 times increase as the cement content changes from 5% to 12%. Similarly the modulus increases by 2.5 to 5 times as the dry density increases from 15.7 to 19.62 kN/m3 and (c) the modulus of CSRE and masonry in dry state are nearly equal, whereas in wet state masonry has 20% less modulus. Compressive strength and behavior of storey height CSRE walls subjected to concentric compression was studied. The results of the wall strength were compared with those of wallette and prism strengths. The wall strength decreases with increase in slenderness ratio. There is nearly 30% reduction in strength as the height to thickness ratio increases from 4.65 to 19.74. It was attempted to calculate the ultimate compressive strength of CSRE walls using the tangent modulus theory. At higher slenderness ratios, there is a close agreement between the experimental and predicted values. The storey height walls show lateral deflections as the load approaches failure. The walls did not show visible buckling and the shear failure patterns indicate material failure. The shear failures noticed in the storey height walls resemble the shear failures of short height wallette specimens. The thesis ends with a summary of the results with concluding remarks in the last chapter.