The primary purpose of pile foundations is to transfer vertical loads due to the transfer of the weight of the superstructure to the deeper ground. However, many civil engineering structures, such as bridges, transmission towers, tall chimneys, and solar panels, are subjected to significant lateral loads and overturning moments in addition to axial loads. Potential sources of lateral loads (not due to earthquakes) include wind, waves, ice forces, passive earth pressure, etc. On the other hand, axial loadings can be live loads from a structure, forces developed due to ground freezing, etc. Consequently, pile foundations for these structures should be adequately designed to resist compressive loads combined with lateral and uplift loads and moments. In most cases, these forces (compressive, lateral, and uplift) and moments are often simultaneously applied on the piles. One of the key objectives for the engineer and designer is to determine the deflections and stresses in a pile in order to keep them within tolerable limits. Passive soil resistance can be very effective in proving lateral support for the pile. However, passive soil resistance is a function of the soil thermal regime (freezing, thawing, and temperature). Due to global warming, the thermal regimes of the soils in Canada and other cold regions in the world have changed in the past decades. The change in the thermal regimes of the soil may affect the geotechnical response or performance of the pile foundations. This thesis presents and discusses the results of physical model testing on model piles in unfrozen, frozen, and thawing fine sand, which are subjected to individual and combined axial (uplift) and lateral loads. The dimensions of the pile model are established by using physical scaling laws. The physical model is also equipped with various sensors and instruments (e.g., linear variable differential transformer (LVDT), and temperature sensors) to monitor the pile and soil response during and after loading. The results of the study show that the thermal regime in the soil significantly affects the performance of the pile under combined loadings (lateral and uplift). The lateral capacity of the pile under combined loads in frozen soil is increased by 648% compared to that in unfrozen ground whereas the uplift capacity under combined loadings in frozen soil is increased by 29%. Due to the effects of the freezing and thawing (F-T) cycles of the soil, a steady increase in the lateral capacity of the pile under the combined loadings is observed. On the other hand, the uplift capacity under the combined loadings in soil subjected to F-T cycles remains constant. The results will be useful in the geotechnical design of pile foundations for bridges and other structures in Canada and other cold regions in the world. The findings of this research will contribute to efficient design practices for pile foundations in cold regions with rapid changing climatic conditions.

Dans le contexte énergétique mondial actuel, les piles à combustible à membrane échangeuse de protons constituent une solution prometteuse au futur développement d'une nouvelle génération de véhicules électrifiés, permettant une autonomie plus importante que celle des véhicules électrifiés à batteries. Néanmoins, le développement à grand échelle des piles à combustible reste à ce jour limité en raison de certains verrous technologiques, tel que la gestion de l'eau. Afin de permettre une production de masse des piles à combustible, de tels problèmes doivent être résolus. Plusieurs axes de travail peuvent être envisagés, tant sur les aspects matériels sur la structure de la pile, que du point de vue de la commande en développant des outils algorithmiques permettant le suivi de l'état de fonctionnement du système en vue de détecter les défaillances éventuelles, ou la dégradation des conditions de fonctionnement, et permettre ainsi d'y apporter une solution au moyen du système de commande ou de supervision.Les travaux de cette thèse s'inscrivent dans cette seconde approche et portent plus particulièrement sur la mise en évidence des phénomènes d'engorgement ou d'asséchement du cœur de pile afin de diagnostiquer les éventuels problèmes d'hydratation conduisant à la réduction du rendement, à la diminution des performances ou encore à un vieillissement prématuré.Les méthodes développées au cours de ces travaux se fondent sur des stratégies de suivi de paramètres significatifs d'un modèle de pile dont les évolutions, comparativement à des valeurs de référence, sont caractéristiques de l'état hydratation du cœur de pile. Le suivi en temps réel de ces paramètres permet ainsi de mettre en évidence les phénomènes d'engorgement ou d'asséchement du cœur de pile.Les modèles adoptés pour ces travaux font appel à une représentation de l'impédance électrique de la pile.Ainsi, en suivant cette approche, la stratégie adoptée se fonde alors sur le développement de deux modèles de type circuit électrique : un modèle d'ordre entier puis un modèle d'ordre fractionnaire. Cette deuxième formulation des modèles, plus proche de la réalité physique des phénomènes de transports se produisant au cœur de pile, permet une meilleure représentation de la pile tant du point de vue temporel que fréquentiel. En effet, les analyses effectuées en utilisant des résultats expérimentaux obtenus au moyen d'une cellule de pile (surface active de 100 cm2 conçue par la société UBzM) ont permis de valider que le modèle d'ordre fractionnaire, en contrepartie d'une augmentation de la complexité, permet de mieux reproduire d'une part les résultats temporels de la pile (suivi de tension pour un profil de courant donnée), d'autre part une meilleure approximation de l'impédance mesurée.Des méthodes d'identification paramétrique, conventionnelles et adaptées aux systèmes d'ordre fractionnaire, sont ensuite utilisées afin d’extraire les paramètres des modèles développés à partir de données expérimentales temporelles (tension/courant de la pile), ou fréquentielles (spectroscopie d'impédance). Une étude de sensibilité permet alors de définir les paramètres les plus indicatifs des phénomènes d'engorgement et d'assèchement. L'évolution de ces paramètres, associés à la tension et le spectre d'impédance de la pile, sont alors combinés afin de construire une stratégie de diagnostic de l’engorgement et de l’asséchement du cœur de pile. / In the current global energy context, proton exchange membrane fuel cells represent a promising solution to the future development of a new generation of electrified vehicles, allowing greater autonomy than electrified vehicles using batteries.Nevertheless, the large-scale development of fuel cells remains limited due to some technological locks, such as water management. To enable mass production of fuel cells, such problems must be solved. Several working axes may be envisaged both on the hardware aspects of the fuel cell structure, and from the point of view of control, by developing algorithmic tools for monitoring the operating state of the system to detect any failures, or degradations that may occur.The work of this thesis falls within this second approach and focuses specifically on the identification of drying and drowning phenomena which can appear in a fuel cell, to diagnose any moisture problems leading to yield reduction.The methods developed in this work are based on the monitoring of relevant parameters of the fuel cell model which changes, compared to reference values, are characteristic of the state of the fuel cell hydration.The real-time monitoring of these parameters can highlight the drying and drowning phenomena.Adopted models for this work are based on a representation of the electrical impedance of the fuel cell.Thus, following this approach, the adopted strategy is then based on the development of two electrical models: an integer order model and a fractional order model. It appears that the second model formulation is closer to the physical reality of transport phenomena occurring in the fuel cell. It allows a better representation of the fuel cell behavior in time and frequency domain. Indeed, the analyzes based on experimental results performed using a single fuel cell (100 cm2 active area designed by UBzM company) have validated that the fractional order model, in return for an increase of complexity, allows better reproduce, in the one hand of the fuel cell time-series voltage response (voltage monitoring for a given current profile), on the other hand a better approximation of the measured impedance. Conventional and of fractional order parametric identification methods are then used to extract the model’s parameters from time-series experimental data (voltage / current from the battery) or frequency data (impedance spectroscopy).A sensitivity analysis allows then the defining of the most indicative parameters of the drowning and drying phenomena. The evolution of these parameters associated with the voltage and impedance spectrum of the fuel cell are then combined to build a diagnosis strategy of the fuel cell water management.

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This thesis wants to save character and identity of local territory and bring a new function in to the historical objects. So it offers comfortable and special living and brings new values for the local inhabitants.

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Full-scale dynamic lateral load tests were performed on a pile cap with a dense silty sand backfill condition. Two hydraulic load actuators connected a test pile cap with a reaction cap. The load actuators incrementally loaded the test cap up to 50 mm of displacement. After each load increment, the displacement was held constant while an eccentric mass shaker induced dynamic loads under a ramping sequence from 1 Hz to 10 Hz. A baseline response was developed under a no backfill condition. Passive soil pressure was measured using pressure cells and tactile sensors. It was concluded that the presence of the backfill significantly increased the lateral load resistance of the pile-cap system, with the resistance nearly doubling at a 50 mm deflection level. After initial loading, the pile cap system experienced a loss in load resistance. In the case with backfill present, this relaxation generally represented a 10 to 15% loss in resistance. Additionally, after undergoing dynamic, cyclic loading, the resistance was approximately 40 to 80% of its initial value. Dynamic displacement amplitudes were on the order of 0 to 2 mm. Passive pressure from the backfill was observed to be non-linear with a concentration of pressure near the bottom of the pile cap. Rankine, Coulomb, and log-spiral earth pressure theories underestimated the passive earth pressure from the backfill by at least 30%. The natural frequency of the pile cap increased with increasing with static displacement level while placement of the backfill further increased the frequency of the pile cap. On average, the presence of the backfill increased the reloading stiffness of the pile cap by a factor of three to four, whereas the damping ratio increased by a factor of two. The dense silty sand backfill acting by itself on the face of the 1.12 m tall and 5.18 m wide pile cap face exhibited a reloading stiffness on the order of 120 to 250 kN/mm and a damping ratio of 30 to 70%. These damping ratios are significantly higher than that typical expected for structural materials but appear to be consistent with values for soils.

Pile caps are used in foundation design to aid multiple single piles to act as a pile group to resist lateral forces that may cause overturning moments. The pile cap and pile group resist these forces by pile-soil-pile interaction, base and side friction along the pile cap-backfill interface, and passive earth resistance. Passive earth resistance has been neglected in design due to a limited amount of full-scale testing. This research presents the results of a combination of hydraulic actuator and eccentric-mass shaker full-scale testing of a pile cap with loose silty sand backfill to quantify the contribution of the passive earth resistance to the lateral force resistance. The test cap is 1.12 m tall and 5.18 x 3.05 m in plan view, connecting 12 steel pipe piles (324mm O.D) placed in a 4 x 3 pattern with center-to-center spacing of 4.4 and 3.3 pile-diameters in the long and short dimensions, respectively. The hydraulic actuator applied a static load to the system (backfill + pile group) while the eccentric-mass shaker introduced cyclic and dynamic loading to the system. The passive earth resistance accounted for approximately 22% of the total system resistance, with piles contributing approximately 78%. Furthermore, the results produce general correlations between cyclic and dynamic effects on degradation of the backfill provided by the testing and soil characteristics obtained, including target (static) displacement, dynamic displacement amplitude, stiffness, and damping. The dynamic displacement amplitudes during the eccentric mass shaker tests typically ranged between .4 and 2 mm for frequencies between 5 and 9.5 Hz representing behavior under reloading conditions rather than virgin loading conditions. Generally, the presence of the loose silty sand backfill nearly doubled the dynamic stiffness of the pile cap. The stiffness of the backfill and pile cap combined was typically between 100 and 200 kN/mm for frequencies between 4 and 8 Hz, while the stiffness for the backfill alone was typically a decreasing trend between 100 and 40 kN/mm for the same frequency range. The overall isolated loose silty sand damping ratio shows a general increasing trend with values from 32% to 55% for frequencies 3 and 8 Hz.

In order to design more efficient and reliable structures, axial load tests are performed on foundation piles. Traditionally, static tests with an average duration of approximately twenty-four hours have been performed on test piles to obtain their axial capacity. These static tests require multiple piles used as anchors in addition to the test pile. Static tests are both expensive and time consuming. An alternative to static testing is dynamic testing which requires sophisticated interpretation, can damage the pile and may not produce accurate results. There is a relatively new testing method called the Statnamic Testing Method which tests foundation piles at a very fast rate, but still slower than with dynamic tests. As the rate at which load is applied to a test pile increases, the axial capacity also increases, particularly in clay. Research suggests that shear strength of soil typically increases 10% per log cycle increase in strain rate. Strain rate effects can vary widely and may be influenced by many factors including plasticity index, structure, ageing, overconsolidation ratio, temperature, etc. Statnamic testing was performed for this work. Nine static tests were performed on six different piles identical to the Statnamic test pile and driven through the same soil profile. The static tests had times to failure ranging from ten seconds to eighteen hours. Failure load increased by 13.7% per log cycle increase in velocity. Statnamic tests need more careful analysis when performed in clay to avoid over predicting pile capacity. A factor of 0.55 should be applied to Statnamic capacity to predict static capacity.

Deep foundations constructed in liquefiable soils require specialized design. The design engineer of such foundations must consider the effects of liquefaction on the foundation and overlying structure, such as excessive settlement, loss of skin friction at the soil-pile interface, and the development of downdrag on the pile. Controlled blasting was employed to liquefy a loose, saturated sand in order to test the liquefaction prevention capabilities of full-scale, vertical composite earthquake (EQ) drains and to investigate the development of downdrag on full-scale test piles. Blasting produced liquefaction at a test site without EQ drains which eventually resulted in 270 mm of settlement. Liquefaction caused the skin friction on the test pile to decrease to zero immediately following blasting. As pore pressures dissipated and the sand settled, negative skin friction developed, with a maximum magnitude of about onehalf of the positive skin friction. Blasting also produced liquefaction at a site with drains but the settlement was reduced to 225 mm, a decrease of 17% relative to the untreated site. Nevertheless, the dissipation rate dramatically increased. Skin friction did not decrease to zero in the liquefied sand and negative skin friction increased to a value equal to the positive skin friction in the liquefied layer. The computer software, FEQDrain, was utilized to develop a calibrated model of the soil profile using pore pressure and settlement data measured during blast testing. This model was then used to simulate drainage systems with smaller drain spacing and larger drain diameter. Results indicated that pore pressures and settlement could be limited to levels acceptable for many applications. However, development of downdrag on deep foundations would not likely be prevented. EQ drains provide an attractive method of liquefaction mitigation. Furthermore, liquefaction can cause significant amount of downdrag on pile foundations which should be accounted for in deep foundation design.