In Trinidad the implications of high sediment concentrations in the rivers are becoming a major concern. Three models were used to estimate sediment loads from soil loss due to rainfall in the 41 km2 St. Joseph River Catchment. The models were the empirically-based RUSLE and MUSLE for annual and single event loading predictions, respectively and the physically based, Erosion 3D, for single event loading predictions. A hydrologic network was constructed that included an on-line Optical Backscatter sensor (OBS), and a water quality sampler. RUSLE overpredicted the measured sediment yield for the year 2006 seven-fold. MUSLE provided reasonable estimates for rain events greater than 10 mm. For Erosion 3D, estimates for rainfall depths greater than 6 mm were reasonably predicted. For both models, estimates improved with increasing sediment load and rainfall depth. / En Trinidad les implications de la haute concentration de sédiments devient un grand souci. Trois modèles ont été utilisés pour estimer les quantités de sédiments des pertes du sol causé par la pluie dans les 41 Km2 de St. Joseph River Catchment. Les deux modèles empiriques ont été RUSLE et MUSLE pour la prédiction d'événements simples et le modèle physique, Erosion 3, utilisé aussi pour la prédiction d'événements simples. Un réseau hydrologique a été construit en incluant un Optical Backscatter sensor (OBS) en ligne, et un échantillonneur de la qualité de l'eau. RUSLE a prédit sept fois plus de sédiments pour l'année 2006 que la valeur réelle mesurée. MUSLE a prouvé être un modèle précis lorsque les pluies atteignent plus de 10mm de colonne. Erosion 3D est considéré précis pour des hauteurs de colonne de plus de 6mm. Les deux modèles deviennent plus précis en fonction de l'augmentation de la quantité de sédiments, et de l'hauteur de la colonne d'eau.

Due to the anthropogenic activities, the increasing carbon dioxide concentration in the atmosphere is disturbing the natural equilibrium of the greenhouse gas, and causes the global temperature rise. In 1990, the CO2 emission from fossil fuel fired power plants contributed 30% of global emissions. In the same year, the cement industry contributed about 5% of the total. According to Kyoto Protocol, a tremendous effort is required to reduce the carbon dioxide emission. One potential technology in CO2 mitigation responses is the use of concrete products as carbon sink through the early age fast curing. The cement compounds C3S and C2S are instantaneously carbonized into calcium carbonate and silica gel, once cement is mixed with water and exposed to the carbon dioxide gas. If it works, concrete production lines can be set next to the power plants or cement kilns to produce the concrete products using the captured CO2 as curing agent. This thesis reports a feasibility study based on a preliminary work. The purpose of the research was to find a proper combination of a large number parameters to use cement, slag or waste cement to sequester CO2 emitted from industrial point sources, and at the same time to make high performance concrete products. In order to understand the carbonation curing, this study was directed towards the mix designs, carbonation conditions and the mechanical properties of carbonated products. More than 40 batches of carbonated concrete specimens were prepared with the following variables in their preparation: chemical additive, CO2 concentration, carbonation time, carbonation pressure, thickness of specimen, and CO2 supply method. The performance of the carbonated specimens was assessed through the mass gain, the compressive strength, the bending strength, the pressure drop, the temperature rise in the curing chamber, the carbonation depth and the microstructure characteristics. Two-hour carbonated concrete products can have a strength equivalent to 2-month air curing, and take up 8% carbon dioxide by weight without special treatment.

This thesis presents the experimental modelling of Light Non-Aqueous Phase Liquids transport in partially saturated with water sand using centrifuge tests, which were carried out at the Geotechnical Centrifuge facility located at Delft Technical University (The Netherlands). The experimentation consisted of a two-dimensional three-phase flow (air, water, Light Non-Aqueous Phase Liquids) in an unsaturated sand for two values of porosity. The Light Non-Aqueous Phase Liquids used in this research was a multigrade motor oil. The modelling of a two-dimensional flow and the use of a transparent strongbox enabled the direct observations of the experiments. Scaling laws developed in connection with other studies available in the literature were used. Tests were conducted at two different gravity accelerations, 20g and 30g, in order to verify, by means of the "modelling of models " technique, the similitude between the different experiments. The thesis covers details of the experimental methodologies and the measurement techniques which where used to evaluate the final water and LNAPL content in the experiments.

In laboratory-scale flumes, flows of dry granular material develop roll waves under certain flow conditions. Water-saturated debris flows formed in a large-scale flume (95 m x 2 m) designed by the U.S. Geological Survey also exhibit roll waves. This work explores the characteristics of these waves. It focuses primarily on the wave profile and speed. / Using a discontinuous theoretical solution of the shallow water wave equations, it is possible to predict wave speed, depth and period and to compare these values to the experimental results from both systems. The theoretical solution assumes that the discontinuous roll wave profiles can be connected through travelling shock waves. The height of a granular shock wave moving downstream must then match that of the roll waves for a particular flow condition. This method of predicting the wave depth was tested against the experimental evidence and was fairly successful. / A power spectral density analysis of the larger scale debris flows exhibited no fundamental periodicity. The controlled granular chute flows, however had increased spectral densities in fairly wide low-frequency bands. This zone of increased spectral power may correspond to the natural frequencies of a quasi-periodic phenomenon.

Many concrete structures built in the 1960s and 1970s are now showing significant signs of deterioration. The Dickson Bridge, constructed in 1959, was decommissioned by the City of Montreal in 1994 due to extensive deterioration of the bridge deck. A collaborative research investigation was carried out in 1997--8 on the bridge to: (a) assess the corrosion induced damage in the concrete deck, (b) identify the causes of the observed deterioration, and (c) investigate suitable test techniques for predicting corrosion. The results of this collaborative research program between McGill University and The Queen's University of Belfast, Northern Ireland, and some industrial partners, are presented in this thesis. / A range of test methods related to the mechanisms causing corrosion, or to the concrete properties indicative of the probability of corrosion was used. Both methods (measuring damage, and measuring material properties and exposure parameters) were used to predict the corrosion rate of the reinforcing steel. Overall, the measurement of the corrosion potential was of important significance, however, to improve the assessment of the likelihood of corrosion, it was advantageous in combining this technique with a survey of the delamination, concrete cover thickness and chloride profiles. (Abstract shortened by UMI.)

The effects of high-strength concrete on the seismic performance of reinforced concrete exterior beam-column-slab subassemblages were investigated by comparing the behaviour of three full-scale specimens. Two specimens, one constructed with normal-strength concrete and one constructed with high-strength concrete, were designed with square columns. The specimen tested in this thesis was constructed with high-strength concrete and designed with a circular column. All the specimens were designed as ductile moment-resisting frames and tested under reversed-cyclic loading. / The Canadian Standard, CSA A23.3-94, limits the concrete compressive strength used in seismic design to 55 MPa. The applicability of the current design specifications, developed for normal-strength concrete, were investigated when applied to ductile beam-column joints made with higher strength concrete. The reduced amount of confinement reinforcement permitted by the New Zealand Standard is also investigated. All specimens in the study were instrumented to allow for detailed strain, load and deflection measurements to be monitored during testing process. The hysteretic behaviour of each specimen was analysed in order to investigate energy dissipating characteristics as well as attainable ductility levels. Strains in the slab bars were used to determine the amount of effective slab reinforcement which contributes to the negative flexural capacity of the main beam. Deflection and strain measurements were used to determine the full torsional response of the spandrel beams. Non-linear dynamic analyses were also performed to compare the predicted seismic performance of normal-strength concrete and high-strength concrete prototype structures.

Urbanisation is a phenomenon that has continued undisturbed since the rise of the industrial era. As the populations of cities increase so do the needs and demands associated with urban expansion. These include the provision of adequate infrastructure to support and sustain the current quality of life, while also planning prudently for future growth. However this continued intensified land use progressively presents challenges to planners and operators alike. It is for this reason that engineers are opting to use underground space as an alternative means of meeting societal needs without significant disruption to activities at the surface. Tunnels are therefore becoming increasingly useful for inspecting and retrofitting buried facilities; buried transportation routes can be seen in subway lines and tunnelled highways. However these services cannot exist without adequate knowledge of the ground in which they exist. It is therefore imperative that studies be done in order to understand as much as possible the intricacies of soil-tunnel interaction. A review of the literature has shown that overwhelming attention has been placed on modelling tunnels in isotropic, homogeneous media, whether those models be empirical, analytical, physical or numerical. However soils in nature are neither homogeneous nor isoptropic. Therefore the objective of this thesis was to examine the soil-tunnel interaction within an excavation in layered ground. A flexible aluminum lining sleeve was placed inside of a cavity excavated out of a cohesive medium for the purpose of monitoring the reaction stresses and bending moments arising from contact with the encroaching soil. A granular stratum was introduced within the cohesive soil at varying elevations ab / L'urbanisation est un phénomène qui n'a cessé de croître de manière continue depuis l'apparition de l'ère industrielle. À mesure que les populations citadines augmentent, les besoins et les demandes liés à l'expansion urbaine augmentent également. Ceux-ci incluent l'approvisionnement en infrastructures capable de répondre à la fois aux besoins de la population et à satisfaire sa qualité de vie, tout en projetant prudemment vers l'horizon afin d'anticiper la croissance urbaine. Cependant cette continuelle expansion de terrain aménagé présente graduellement des défis aussi bien aux planificateurs qu'aux opérateurs. C'est pour cette raison que les ingénieurs optent pour l'exploitation des espaces souterrains comme moyen alternatif, dans le but de satisfaire les besoins sociaux sans perturber de manière significative les activités menées en surface. Les tunnels deviennent donc de plus en plus utiles pour l'inspection et la mise à niveau des équipements enterrés; des voies de transport telles que les lignes de métro et les autoroutes souterraines peuvent également être rencontrées. Cependant ces services ne peuvent exister sans une connaissance adéquate du sol dans lequel ils existent. Il est donc impératif que des études soient faites afin de comprendre autant que possible les complexités de l'interaction sol-tunnel. Une revue de la littérature a montré qu'une attention particulière a été placée sur la modélisation des tunnels dans des milieux isotropes et homogènes aussi bien pour des modèles empiriques, analytiques, physiques ou numériques. Cependant les sols naturels ne sont ni homogènes ni isotrope. Par conséquent l'objectif de cette thèse consistait à examiner l'interaction sol-t

Half-scale models of two-way column-footing hinge connections were tested under constant axial load and reversed cyclic lateral load. In one of the specimens, the column and hinge were circular in cross section; in the other specimen, the column and hinge were square in cross section. The main objective was to assess the seismic performance of these details, which are common in existing bridge structures in moderate seismic regions. / The test results confirmed that the lateral column displacement was due almost entirely to rotations in the hinge. Horizontal slip at the hinge and flexural deformation in the column were insignificant prior to hinge gap closure, which occurred at large column displacements. Hinge gap closure resulted in sudden increases in stiffness and strength, but these increases occurred at column displacements which would be excessive in the prototype structure. The hinge responses are characterized by hysteretic pinching, poor energy absorption and significant stiffness degradation. / The measured moment-curvature responses of the hinge regions are compared predicted monotonic responses. Special attention is given to the effect of confinement on the hinge concrete in increasing the strength and the ductility of the concrete.

Concrete dams suffer from many forms of deterioration and specifically the presence of internal cracks. Presently, the borehole technique is used to evaluate the orientation of the cracks and the mechanical properties of the concrete. High costs are associated to this method as well as the need to extrapolate results between adjacent boreholes. Nondestructive testing is seen as a possible solution for reducing high inspections costs and increase the precision of crack location. This thesis presents the theoretical and practical aspects of a nondestructive method called the Miniature Seismic Reflection (MSR Impact-Echo) system. The system can evaluate a crack profile and determine the quality of concrete from one test surface. The objective of the research is to extend the capabilities of the system to crack detection in large scale concrete structures. Results are presented with respect to inclined crack detection, the minimum crack thickness detectable, and tests performed on a section of a concrete gravity dam. The experiments are part of a long term research project between McGill University and the "Institut de Recherche en Electricite d'Hydro-Quebec (IREQ)".

The punching shear behaviour of interior slab-column connections in flat plates is investigated. The response of six two-way slab specimens, which were designed such that they would fail in punching shear, are presented. The parameter introduced in the experimental program is member depth. The effects of this parameter on the punching shear capacity of slab elements are investigated. The results show a strong "size effect", with deeper members having a smaller shear stresses at failure than shallow ones. / Test results obtained from this experimental program are compared with the punching shear predictions of the Canadian CSA A23.3-94 Standard, the American ACI 318-95 Code, the British BS 8110-85 Standard and the European CEB-FIP 1990 Model Code. Predictions were also made using computer program "Response 2000", assuming an equivalent beam analogy to represent the slab. It is concluded that the shear design of slabs, according to the current Canadian and American codes, can be unconservative under certain conditions, particularity for thick slabs. It is recommended that the punching shear expressions of the CSA Standard and the ACI Code be modified to take into account the "size effect" on the punching shear strength of slabs.