No description available.

A new spatially telescoping approach was proposed to improve measurement flexibility and account for hydrologic scale in field studies of groundwater-surface water (GW-SW) interaction. We applied this spatially telescoping approach in a study GW-SW interactions along Lucile Creek, Alaska. Catchment-scale data were used to screen areas of potentially significant GW-SW exchange, indicating groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during base flow conditions. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Point measurements of vertical water fluxes were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatially telescoping approach identified locations of GW-SW exchange and improved interpretation of reach-scale and point-scale measurements.

The efficacy of injection-driven remediation techniques for non-aqueous phase liquid (NAPL) source zones is limited by the principle that fluid flow is focused along paths of least hydraulic resistance. The pressure pulse technology stands among a number of innovative methods that have been developed with the aim of overcoming or mitigating this limitation. The objective of this research was to observe and document differences in saturated groundwater flow and solute transport between an injection using a conventional or continuous pressure delivery approach and an injection using a pressure pulsing instrument. The underlying motivation was to identify engineering opportunities presented by pressure pulsing with the potential to improve remediation efficiency at contaminated sites. A series of tracer injections were conducted in the unconfined aquifer at the University of Waterloo Groundwater Research Facility at Canadian Forces Base (CFB) Borden near Alliston, ON (homogeneous fine sand), and in the shallow aquifer at a groundwater research site located on the North Campus at the University of Waterloo (moderately heterogeneous with discrete layers varying from fine sand to silt). A single injection well was used at each site for both the conventional and pressure pulsing injections. Different tracers were used for consecutive injections. Bromide, Lithium, Chloride, and fluorescent dyes (Rhodamine WT and Sulforhodamine B) were used. Formation pressurization data was captured by pressure transducers. The spatial distribution of the injected tracers was monitored at a series of multilevel wells. A groundwater flow and solute transport modeling exercise (MODFLOW and MT3DMS numerical engines) simulating the rapid boundary pressure modulation that occurs in association with pressure pulsing was conducted to complement the field injections. A two-dimensional domain was used to conduct a parametric investigation of pressure modulation and its effect on flow and transport. A three-dimensional domain served to scale-up the two-dimensional results and for benchmarking against field observations. Pressure pulsing simulation results reveal that repeated sudden onset of injection cessation produces brief periods of gradient reversal near the injection well and the development of a mixing zone around the injection well. The spatial extents of this mixing zone are highly dependent upon the hydraulic diffusivity of the medium. Greater heterogeneity in combination with presence of high hydraulic diffusivity pathways maximized the extent of the mixing zone and the magnitude of transverse and reversal hydraulic gradients. Lower pulsing frequency and higher pulsing amplitude favoured a more significant mixing zone, though these effects were secondary to geologic properties. Use of the pressure pulsing tool did not manifest into distinct changes in tracer breakthrough at either field research site. Comparison between tracer tests was complicated by sorption of fluorescent dyes and ongoing well development. Solute transport simulation results demonstrated augmentation of dispersion arising from the mixing zone phenomenon, but no distinct changes in advection.

The efficacy of injection-driven remediation techniques for non-aqueous phase liquid (NAPL) source zones is limited by the principle that fluid flow is focused along paths of least hydraulic resistance. The pressure pulse technology stands among a number of innovative methods that have been developed with the aim of overcoming or mitigating this limitation. The objective of this research was to observe and document differences in saturated groundwater flow and solute transport between an injection using a conventional or continuous pressure delivery approach and an injection using a pressure pulsing instrument. The underlying motivation was to identify engineering opportunities presented by pressure pulsing with the potential to improve remediation efficiency at contaminated sites. A series of tracer injections were conducted in the unconfined aquifer at the University of Waterloo Groundwater Research Facility at Canadian Forces Base (CFB) Borden near Alliston, ON (homogeneous fine sand), and in the shallow aquifer at a groundwater research site located on the North Campus at the University of Waterloo (moderately heterogeneous with discrete layers varying from fine sand to silt). A single injection well was used at each site for both the conventional and pressure pulsing injections. Different tracers were used for consecutive injections. Bromide, Lithium, Chloride, and fluorescent dyes (Rhodamine WT and Sulforhodamine B) were used. Formation pressurization data was captured by pressure transducers. The spatial distribution of the injected tracers was monitored at a series of multilevel wells. A groundwater flow and solute transport modeling exercise (MODFLOW and MT3DMS numerical engines) simulating the rapid boundary pressure modulation that occurs in association with pressure pulsing was conducted to complement the field injections. A two-dimensional domain was used to conduct a parametric investigation of pressure modulation and its effect on flow and transport. A three-dimensional domain served to scale-up the two-dimensional results and for benchmarking against field observations. Pressure pulsing simulation results reveal that repeated sudden onset of injection cessation produces brief periods of gradient reversal near the injection well and the development of a mixing zone around the injection well. The spatial extents of this mixing zone are highly dependent upon the hydraulic diffusivity of the medium. Greater heterogeneity in combination with presence of high hydraulic diffusivity pathways maximized the extent of the mixing zone and the magnitude of transverse and reversal hydraulic gradients. Lower pulsing frequency and higher pulsing amplitude favoured a more significant mixing zone, though these effects were secondary to geologic properties. Use of the pressure pulsing tool did not manifest into distinct changes in tracer breakthrough at either field research site. Comparison between tracer tests was complicated by sorption of fluorescent dyes and ongoing well development. Solute transport simulation results demonstrated augmentation of dispersion arising from the mixing zone phenomenon, but no distinct changes in advection.

The primary objective of this research project was to perform live load tests on a bridge deck with GFRP reinforcement in the field under service conditions. The strains and deflections in the span reinforced with GFRP in the top mat were recorded under a series of truck crossings, and these were compared to the span reinforced with all steel bars under identical loading conditions, as well as design values and other test results. Transverse strains in the GFRP bars, girder distribution factors, girder bottom flange strains, dynamic load allowances, and weigh-in-motion gauge results were examined. From the live load tests, it was concluded that the bridge was designed conservatively for service loads, with measured strains, stresses, distribution factors, and impact factors below allowables and design values. The second objective was to monitor the construction of the bridge deck. To carry out this objective, researchers from Virginia Tech were on site during the bridge deck phase of the construction. The construction crews were observed while installing both the all-steel end span and the steel bottom/GFRP top end span. The installation of the GFRP bars went smoothly when compared to that of the steel bars. The workers were unfamiliar with the material at first, but by the end of the day were handling, installing, and tying the GFRP bars with skill. It was concluded that GFRP bars are an acceptable material in bridge deck applications with respect to constructibility issues. The third objective was to set up the long term monitoring and data collection of the bridge deck. Electrical resistance strain gauges, vibrating wire strain gauges, and thermocouples were installed in the deck prior to concrete casting to provide strain and temperature readings throughout the service life of the bridge. It was concluded that the span reinforced with GFRP was instrumented sufficiently for long-term health monitoring. / Master of Science

The purpose of this research was to investigate the effectiveness and durability of GFRP bars as reinforcement for concrete decks. Today's rapid bridge deck deterioration is calling for a replacement for steel reinforcement. The advantages of GFRP such as its high tensile strength, light weight, and resistance to corrosion make it an attractive alternative to steel. The first objective of this research was to perform live load testing on a bridge deck reinforced with GFRP in one span and steel in the other. The results were compared to the findings from the initial testing performed one year earlier. The strains and deflections of the bridge deck were recorded and the two spans compared. Transverse stresses in the GFRP bars, girder distribution factors, and dynamic load allowances were calculated for both spans. From the live load tests, it was concluded that the GFRP-reinforced span results were within design parameters. The only concern was the increased impact factor values. The second objective was to perform live load tests on a slab reinforced with GFRP installed at a weigh station. Two live load tests were performed approximately five months apart. Peak strains in the GFRP and steel bars were recorded and compared. The peak stresses had increased over time but were within design allowable stress limits. The third objective of this research was to investigate the long term behavior and durability of the GFRP reinforcing bars cast in a concrete deck. The strain gauges, vibrating wire gauges, and thermocouples in the bridge deck were monitored for approximately one year using a permanent data acquisition system. Daily, monthly, and long term fluctuations in temperature and stresses were examined. It was concluded that the vibrating wire gauges were more reliable than the electrical resistance strain gauges. It was further observed that the main influence over strain changes was temperature fluctuations. / Master of Science

Résumé : La connaissance de la fiabilité d’une structure dans sa durée de vie est d’une importance stratégique. Plusieurs méthodes non destructives ont ainsi été développées pour évaluer l’état des ouvrages en béton. Parmi ces techniques, les méthodes basées sur l’acoustique non linéaire ont démontré une performance satisfaisante en laboratoire pour détecter les microfissures de façon précoce. L’objectif de cette thèse consiste à apporter de nouvelles idées contribuant au développement de la méthode du saut temporel ultrasonore (en tant que méthode acoustique non linéaire) pour l’évaluation in situ des structures en béton. Ce travail porte plus particulièrement sur la caractérisation du béton atteint de réaction alcalis-silice (RAS). L’originalité de ce travail réside principalement dans l’utilisation des sollicitations naturelles auxquelles les ouvrages d’art sont soumis comme source d’excitation du milieu pendant l’application du saut temporel (ST). La sollicitation fournie par le passage d’un véhicule sur un tablier d’un pont est l’un des exemples de ces sources naturelles. Un programme expérimental a donc été mis sur pied, qui consiste en une phase d’étude au laboratoire et à une phase d’étude sur site. Deux dalles de béton réactif et une dalle de béton non réactif (1,40×0,75×0,3 m[indice supérieur 3]) ont été fabriquées en laboratoire afin d’évaluer l’idée générale de cette thèse. Pour générer les ondes d’excitation de basses fréquences requises pour les essais ST, un vérin hydraulique a été utilisé comme sources d’impact simulant le passage d’un véhicule. Avec ce protocole d’essais, la progression de la RAS a été caractérisée dans les dalles réactives. Il a été démontré que le ST peut détecter sans équivoque la RAS à partir d’une expansion de 0,03%. Les résultats montrent également que la perturbation des éléments structuraux par le passage d’un véhicule serait exploitable pour les investigations in situ. L’effet de la température sur le comportement acoustique non linéaire du béton a également été étudié : les mesures acoustiques non linéaires sont plus fiables dans une plage de température entre 10[degré]C et 30[degré]C. Des essais préliminaires ont été effectués sur le tablier d’un petit pont en béton. Les perturbations requises ont été fournies par le passage d’un camion dans une plage de vitesses variant de 20 km/h à 50 km/h; en utilisant deux types d’excitation (naturelle et amplifiée en utilisant des obstacles). Les résultats ont démontré qu’on peut appliquer la méthode ST sur site en utilisant l’excitation naturelle générée par un camion. Les expériences faites dans cette thèse révèlent la faisabilité de la méthode du ST pour évaluer l’état des structures en béton, notamment celles qui sont dégradées par la RAS. // Abstract : Reliability of a structure during its service life is strategically important. Several non-destructive methods have been developed to evaluate the condition of concrete structures. Among these techniques, the methods based on nonlinear acoustic have shown an excellent performance in laboratory for detecting micro-cracks at early ages. The objective of the thesis is to work on new ideas, which may contribute to develop the method of Ultrasonic Time Shift (as a nonlinear acoustic method) for evaluating concrete structures. This thesis focused was on concrete elements suffering from Alkali-Silica Reaction (ASR). The originality of the work is related to the idea that the natural vibrations, which exist in structures, can be used for perturbing structural elements during a Time Shift test. For instance, the vibration generated by a vehicle passing on a bridge is one of the examples of the natural resources of vibration. To reach the objective of this thesis, a research program was conducted in two phases: 1) experiments in laboratory; 2) field experiments. Two concrete slabs with reactive coarse aggregates and one with nonreactive aggregate were fabricated in the lab in order to assess the main idea of the thesis. A hydraulic actuator with an impact form loading pattern was used to generate low frequency waves (used to perturb the test-media) for tests of Time Shift (TS). Such loading pattern is similar to the loading imposed by a vehicle passing on a bridge deck. The progression of ASR-damage in the concrete slabs was successfully tracked using the developed methodology. It was shown that the TS can detect ASR from an expansion level about 0.03%.The results also show that the new methodology used for exciting structural elements can be used for field investigations. The effect of the temperature on nonlinear acoustic behavior of the concrete was also assessed. This investigation revealed that measurements in temperatures ranged from 10oC to 30oC can lead to better results. Some filed tests were carried out on a concrete slab of a small-size bridge. The required perturbations for the tests were provided by a truck. The velocity of the truck ranged from 20 km/h to 50 km/h.; using two types of perturbation (natural and exaggerated using some obstacles on surface). The results showed that the TS is an applicable method for field investigations, where the required perturbations are provided by a truck. The performed experimental program revealed the feasibility of the method of Time Shift for evaluating concrete structures, specifically those damaged by ASR.

The main aim of this work was comparing the supply side of tourism in selected cities (Trebon, Vodnany). After studying the literature was conducted situational analysis that led to the finding of supply of tourism in these cities. The next section was carried out field research in Trebon, who was elected as a city with a diverse range of tourism. In the evaluation of the field investigation and found the results were provided suggestions to improve the current situation in the city and has also designed a product package. The aim of this package is primarily the extension of the current range of supply of destination, increasing its attractiveness and extend visitors' stay in this destination. The package also offers reduced fees for students.