A series of relatively recent bridge failures due to pier scour, as reported in literature, has rekindled interest in furthering our understanding of the scour process and for developing improved ways of protecting bridges against scour. Moreover, increased attention is being given to the state of Canadas infrastructure, a major aspect of which is the transportation network. In part, there is concern about both the impact of a failure on the handling of traffic flow while the failure is being remedied and on the cost of replacing the failed system component. As such, attention is being given to the scour design of new bridges and to the inspection, maintenance and management of existing bridge structures. The two major countermeasure techniques employed for preventing or minimising local scour at bridge piers are increased scour resistance and flow alteration. In the former case, the objective is to combat the erosive action of the scour-inducing mechanisms using hard engineering materials or physical barriers such as rock riprap. In the latter case, the objective is to either inhibit the formation of the scour-inducing mechanisms or to cause the scour to be shifted away from the immediate vicinity of the pier. This research focuses on a particular application of the latter technique. <p> In this study, the use of collars for reducing the effects of local scour at a bridge pier is presented together with the time aspect of the scour development. The adoption of a collar is based on the concept that its existence will sufficiently inhibit and/or deflect the local scour mechanisms so as to reduce the local scour immediately adjacent to the pier. The overall objective of the research is to study the temporal development of the scour for a pier fitted with a collar and a pier without a collar. More specifically, the objectives are: i) to evaluate the effectiveness of a pier collar for mitigating the depth of scour that would otherwise occur at a bridge pier; and ii) to assess the occurrence of an equilibrium scour condition, if achieved, or of the implications of not achieving such a condition in respect of interpreting the results obtained from a physical hydraulic model study. <p>The study was conducted using a physical hydraulic model operated under clear-water conditions in cohesionless bed material. Tests were conducted using two different pier diameters so as to determine the effect of pier diameter on the temporal development of scour for a plain pier. Also investigated was the effect of collar size on the time development of scour and its efficacy at preventing scour at a bridge pier. The time development of the scour hole around the model pier with and without a collar installed was compared with similar studies on bridge piers. Several equations for the temporal development of scour depth and those for the prediction of the equilibrium scour depth were tested as part of this study. <p>The results of the model study indicated that the maximum depth of scour is highly dependent on the experimental duration. The depth of the scour hole increases as the duration of the increased flow that initiates the scour increases. The extent of scour observed at the pier also increases as the duration of the tests increases. It was found that the temporal development of the scour hole at the pier was dependent on whether or not the pier was fitted with a collar placed at the bed level. The pathway to an equilibrium scour depth is different depending on whether the pier is fitted with a collar or not. With a collar in place, the development of the scour hole is considerably delayed. A truly equilibrium scour condition is not readily attainable and was not achieved in the work reported herein. It was demonstrated that wrong conclusions may be reached if a test is stopped short of an equilibrium state. As regards the temporal development of scour depth and for the tests in which no collar was fitted to the pier, it was noted that the form of equation that fits the experimental data well was the one given by Franzetti et al. (1982). Furthermore, it is possible to reach a variety of conclusions about the efficacy of using collars as a pier scour countermeasure technique, depending on which definition of time to equilibrium scour is adopted.

L’étude présentée a pour objectif de mieux comprendre l’influence de l’hydrodynamique sur le transfert de produits phytosanitaires lors d’écoulement dans les fossés agricoles. Quatre paramètres ont plus particulièrement été étudiés : i) la vitesse de l’écoulement de surface ; ii) la submergence, définie comme le rapport moyen entre la hauteur des formes du lit et la hauteur d’eau ; iii) la forme du lit et iv) le degré de saturation en eau du lit avant la contamination par les produits phytosanitaires. L’influence de ces paramètres a été étudiée en conditions semicontrôlées à travers la mise en oeuvre d’expérimentations en canal expérimental, au fond duquel a été fixé pour chaque expérimentation un substrat type constitué d’un assemblage de fibres de chanvre utilisé pour approcher de manière simplifiée un système naturel relativement complexe et hétérogène (en considération des nombreux substrats rencontrés dans le lit des fossés naturels : herbes, feuilles mortes, végétation en décomposition, paille, sédiments, …). Les fibres de chanvre ont été choisies après une étude préliminaire en laboratoire visant à comparer les possibilités d’adsorption et de désorption des produits phytosanitaires sélectionnés sur diverses fibres couramment utilisées dans l’industrie géotextile (jute, lin, chanvre, polyamide, polypropylène et polyester). Les expérimentations en canal expérimental ont été menées de manière à tester l’influence spécifique des paramètres étudiés. La comparaison des différentes expérimentations indique qu’une augmentation de la vitesse de l’écoulement de surface augmente la quantité de produits phytosanitaires transférés de l’écoulement de surface vers le lit, ainsi que la cinétique de ce transfert. Le constat est le même lorsqu’on augmente la submergence, ou bien lorsqu’on passe d’une géométrie de petites formes en « dunes » à une géométrie de grandes formes en « créneau ». Enfin, le fait que le lit soit saturé en eau en début d’expérimentation réduit fortement le transfert de la lame d’eau vers le lit. On observe également que l’influence de chaque paramètre semble être interdépendante. Devant le coût en temps et en argent de ces expérimentations, un modèle a été sélectionné dans la littérature, codé et utilisé pour conforter et compléter l’interprétation des données expérimentales. / The aim of this work was to better understand the influence of hydrodynamics on the transfer of pesticides in water flows in agricultural ditches. Special attention was given to four parameters: i) the speed of the surface water flow, ii) the submergence, defined as the mean ratio between the height of the bedforms and the water depth, iii) the shape of the bedforms and iv) the water content of the bed substrate before contamination by pesticides. The influence of these various parameters was investigated with an experimental flume, using a standard of substrate made of hemp fibres. Hemp fibres were chosen as a simplified model of natural substrates such as grass, dead leaves, decaying vegetation, straw and sediments, which are rather complex and heterogeneous. Hemp fibres were selected from preliminary laboratory studies which allowed to compare the adsorption and desorption characteristics of various pesticides for different fibres often used in the geotextile industry (jute, linen, hemp, polyamide, polypropylene and polyester). The flume experiments were designed in order to assess the influence of the four parameters mentioned above. The comparison between the different experiments shows that an increase in surface water speed results in an increase in the amount of pesticides transferred from the water to the bed substrate and the transfer kinetics. A similar result is observed when increasing the submergence, or when going from small sinusoidal bedforms to larger rectangular bedforms. In addition, the data show that the transfer of pesticides from surface water to the bed substrate is strongly decreased when the substrate was saturated with water at the beginning of the experiments. Also, it appears that there is a link between the influence of the differents parameters. When considering the long time duration and the cost of the experiments, it was decided to use a model from the literature which was adapted and used to confirm and extend the interpretation of the experimental data.

No description available.

La Société le Nickel ’SLN’ est l’un des plus grands exploitants de nickel en Nouvelle Calédonie. Le Stockage des déchets de l’exploitation minière sur le site d’exploitation se fait sous forme de tas manufacturés appelés versants. Pour assurer la stabilité de ces versants, il est nécessaire d’assurer un stockage hors d’eau de ces stériles miniers. Pour se faire, une mise en place des ouvrages en enrochement enterrés se fait au fur et à mesure de l’avancement des travaux d’installation des versants. Le rôle de ces ouvrages enterrés est de maintenir l’écoulement d’eau à travers le milieu poreux. Le premier objectif de la thèse est donc de mieux comprendre les interactions hydrodynamiques dans les milieux très perméables dans le cas d’écoulements pleinement turbulents. La première partie de ce travail concerne une étude expérimentale menée à l’Institut National Agronomique de Tunisie (INAT) mais aussi à l’Institut de mécanique de fluide de Toulouse (IMFT) dont le but est d’étudier à la fois l’évolution de la ligne d’eau dans les milieux macroporeux et la variation de la perméabilité de ces derniers en fonction du nombre de Reynolds. Des simulations avec des modèles de perte de charge les plus utilisés dans la littérature ont été effectuées, pour tester leur capacité à reproduire la ligne d’eau dans les conditions de nos expériences. Les deux relations de Forchheimer (1901) et d’Ergun (1952) donnent des résultats proches de nos expériences avec des valeurs de coefficients adaptés pour notre cas, alors que la relation de Barree et Conway (2004) ne semble pas reproduire les résultats attendus. L’eau qui circule dans les ouvrages enterrés est une eau chargée d’où l’intérêt d’étudier le transport sédimentaire dans ces milieux macroporeux. Pour se faire, une étude expérimentale a été réalisée sur le transport et le dépôt des particules dans des milieux synthétiques constitués de particules de diamètre moyen de 15 cm / The 'SLN' Company is one of the largest nickel operators in New Caledonia. The mining wastestorage at the operation site is as a slope. To ensure the stability of these slopes, it is necessary toensure an out of water storage of the waste rock. To do that, an underground rockfillimplementation is installed. The purpose of these buried structures is to maintain the flow of waterthrough its pores. The first objective of the thesis is to better understand the hydrodynamicinteractions in highly permeable porous media and in case of fully turbulent flows. The first part ofthis work relates to an experimental study carried out at the National Agronomic Institute of Tunisia(INAT) and the Institute of Fluid Mechanics of Toulouse (IMFT) whose aim is to study the waterprofile evolution in macro porous media and the permeability variation as a function of theReynolds number. Simulations with the most widely used pressure drop relationships in theliterature were performed to check their ability to reproduce our experimental water profile. Thetwo relations of Forchheimer (1901) and Ergun (1952) give the most satisfactory results withadapted coefficients values for our case, whereas the Barree and Conway (2004) formula doesn’tseems to give expected results. Given that the circulating water in these buried structures is acharged water, we studied the sedimentary transport in macro porous media. To do this, anexperimental study was carried out on the transport and deposition of particles in the studiedporous media which mean diameter is d=15 cm.

Tidal power, or the use of tides for electricity production, exists in many forms including tidal barrages, which exploit tidal head differentials, and turbines placed directly in regions with large tidal current velocities. The latter is actively being investigated in many countries around the world as a means of providing renewable and wholly predictable electricity (cf. wind, solar and wave power). The expansion of the in-stream tidal industry is hindered however by several factors including: turbine durability, deployment and maintenance costs, and the lack of abundant locations which meet the necessary current velocities for turbine start-up and economic power production. A new novel type of augmentation device, entitled the ‘Tidal Acceleration Structure’ or TAS (Canadian patent pending 2644792), has been proposed as a solution to the limited number of coastal regions which exhibit fast tidal currents. In preliminary investigations, the TAS, a simple Venturi section consisting of walls extending from the seafloor to above the high water mark in an hourglass shape, was found as able to more than double current velocities entering the device. The results indicated a significant advantage over other current channeling technologies and thus the need for more in-depth investigations. The main objective of the present study was to optimise the design of the TAS and to predict the power that a turbine placed within it could extract from flow. To do this, two principal methods were employed. Firstly, a 1:50 scale model of the TAS was tested and its shape optimised in a 1.5 m wide flume. Secondly, a 3D numerical model (ANSYS Fluent) was used for comparison with the experimental results. During the tests, a TAS configuration was found that could accelerate upstream velocities by a factor of 2.12. In separate tests, turbines were simulated using Actuator Disc Theory and porous plates. The TAS-plate combination was found to be able to extract up to 4.2 times more power from flow than the stand-alone plate, demonstrating that the TAS could provide turbines with a significant advantage in slower currents. Though further research is needed, including the testing of a larger TAS model in conjunction with a small in-stream turbine, the results of this thesis clearly demonstrate the potential of the TAS concept to unlock vast new areas for tidal energy development.

This Master’s thesis deals with design of hydraulic circuit of laboratory of the Slovak university of agriculture in Nitra with focus on project of its machine part. The thesis includes a description of current condition of the laboratory and a list of investor’s requirements. The main task of this thesis is to complete a project documentation which will be used to build a hydraulic circuit in laboratoty of Department of Water Resources and Environmental Engineering under Faculty of Horticulture and Landscape Engineering of the Slovak University of Agriculture in Nitra. The hydraulic circuit is based on recirculation concept. It consists of an underground water storage tank, stainless steel distribution pipes, measuring flumes and centrifugal submersible pumps. The hydraulic circuit will serve employees of the university for their scientific and educational purposes. Important parts of this thesis are hydrotechnical calculations and circuit control visualisations. The final design is based on a series of negotiations with the investor and suits his requirements.

Studying the behavior of hydraulic structures under various extreme conditions is far beyond the reach of traditional build-test experimental methods. Following the typical method, it is necessary to provide the downscaled model to be used in the laboratory and determine various structural parameters against unforeseen scenarios, which should be mimicked in the laboratory. Usually, human and instrument errors as well as scale effects are some of the causes of inaccurate results; therefore, substitute methods have always been sought to determine the stability and efficiency of various hydraulic devices. The implementation of computer models, also referred to as numerical simulation, is one of the most efficient ways to reduce time and cost, and at the same time, add to the degree of confidence in the design process. Improvements in computational power of supercomputers in recent decades have led researchers and engineers to become familiar with these numerical models and implement them in various studies. One of the basic hydraulic structures that is widely used to measure the flow for open channels is the Parshall flume. Although the Parshall flume is simple to use, the application of various rating equations for different sizes highly affects the output value, which is the flowrate. To avoid this, appropriate rating equation must be developed for various sizes that are not listed in the standard Parshall flume size chart. With the help of the Computational Fluid Dynamic (CFD) techniques, numerous turbulence models i.e., standard k-ε, RNG k-ε, realizable k-ε, k-ω, k-ω SST, k-ω SST DES, Smagorinsky and Dynamic k equation, have been used to simulate different geometric setups for different sizes of Parshall flumes. The result from various families of turbulence models, i.e., Reynold Average Navier-Stokes (RANS), Large Eddy Simulation (LES) and Detached Eddy Simulation (DES), used in this study, provide promising values with acceptable margins of error, which were found to be less than 3% in all cases except one. The application of numerical modeling to simulate the flow in Parshall flumes is used to verify the reliability of applying OpenFOAM as the open-source CFD used for all the simulations in this study. The data obtained from the numerical simulations are considered a reliable source to adjust the rating equation for any future non-standard Parshall flume. Overall, it should be pointed out that the quality of non-linear turbulence models, i.e., Shih-Q, LC, and v²-f, were considerably higher than those obtained using linear turbulence models.

The diploma thesis deals with an urban and architectural design of a stretch of area along the Svitava raceway and the Ponávka river in Brno, specifically of the locality in the area where the Svitava raceway has already merged with the Ponávka river. The area is situated south of the city centre, in the cadastral maps of Komárov and partly Trnitá. The main objective of the thesis is to find the potential and capacity of the Svitava raceway concerning redevelopment and creation of new municipal areas, especially in the form of embankments designated for pedestrians and cyclists. The design also focuses on the redevelopment and on finding a new suitable functional utilization of the area. The theoretical part of the diploma thesis describes the urban development of the city, its history and the development of Brno region as well as of the rivers in its district. It examines and analyses the prerequisites of the area affecting the design. Complete description and specifications of the proposed design are to be found here. The drawing part deals with the graphic analysis of the area as well as the concretization of the prerequisites influencing the design and it solves the complete urban design accompanied with the detailed local views of the area.

This study is the first to consider how the combination of root physical effects, microbial production of EPS, and root effects on the hydrodynamic boundary layer could influence streambank soil erodibility. Specifically, the goal of this research was to quantify the physical and biological effects of roots on streambank fluvial erosion. A series of laboratory-scale erosion tests were conducted using a mini jet erosion testing device and a recirculating flume channel to address this goal. Several soil and vegetation factors that influence fluvial entrainment, like extracellular polymeric substances (EPS), soil aggregate stability and root length density, were measured following erosion testing. For flume experiments, three streambank boundary conditions were constructed to simulate unvegetated streambanks, as well as streambanks with herbaceous and woody roots. Soil treatments were also created to represent unamended and organic matter (OM) amended soil either without roots (bare soil), with synthetic roots, or with living roots (Panicum virgatum). Median soil erosion rates along the simulated rooted boundaries were two to ten times higher compared to the unvegetated boundary due to protruding root impacts on the boundary layer. In flume experiments, median erosion rates were 30% to 72% lower for unamended soils containing compacted synthetic root fibers as compared to bare soil samples. Adding both OM and fibers to the soil had a greater effect; the median erosion rate reductions of live rooted treatments (95% to 100%) and synthetic rooted + OM treatments (86% to 100%) were similar and statistically lower than bare soil controls. Stimulated microbial production of EPS proteins were significantly correlated with increased erosion resistance in OM-amended treatments while OM treatments had significantly lower EPS carbohydrates compared to unamended treatments. In summary, while sparsely spaced roots exposed on streambanks may increase soil erosion rates due to impacts on the hydrodynamic boundary layer, overall results highlight how the synergistic relationship between root fibers and soil microbes can significantly reduce streambank soil erodibility due to fiber reinforcement and EPS production. / Doctor of Philosophy / Plant roots are known to protect streambank soils from erosion by water; however, exactly how roots provide this protection has remained unclear. Among other things, roots can influence streambank soil erosion by holding soil together through a thick root network, interacting with soil microorganisms to stimulate the release of "sticky" organic compounds called extracellular polymeric substances (EPS), and altering the force of the water against the streambank. This research aimed to quantify and compare the relative importance of these three mechanisms on streambank soil erosion using a mini jet erosion testing device and an indoor recirculating flume channel. To do this in the flume, three walls were constructed to simulate unvegetated streambanks, as well as streambanks with herbaceous and woody roots. In greenhouse settings, soil treatments were also created to represent unamended and organic matter (OM) amended soil either without roots (bare soil), with artificial roots, or with living roots (Panicum virgatum). While roots protruding out of streambanks appeared to increase median soil erosion rates due to the impact of roots on near-bank flow, artificial roots in the soil and OM amended soils reduced soil erosion rates. Specifically, OM amendments stimulated the production of EPS proteins, leading to improved soil stability and increased soil resistance to erosion by water. Overall results highlight how the synergistic relationship between root fibers (living roots and artificial roots) and soil microbes can significantly reduce streambank soil erodibility due to root binding and microbial production of EPS. While plant roots naturally provide both fibers and EPS to soils, these materials could be incorporated into fill soils during construction to rapidly increase soil erosion resistance following levee construction and stream restoration projects.

It is suitable to add practical illustrations of hydraulic tasks during teaching hydraulics and hydrology. These practical illustrations can be realized by mobile hydraulic circuit which is situated in the auditorium. This thesis is focused on constructional and project solution of the circuit which consists of a compensatory tank with sufficient capacity, pump aggregate and hydraulic measure flume. The construction of hydraulic flume must enable quick, simple and safety installation of a scaled down models of a hydro technical structures. The main requirements of a mobile teaching circuit are clearness of practical hydraulic illustrations, compact dimensions, comparatively low weight, mobility and simple control and manipulation. This diploma thesis also includes design of a scaled down models of a hydro technical structures, especially set of plate weirs, bed-crested weir, ogee-crested weir, culvert, Venturi flume, sluice and radial gate, pier and roughened bed. The hydraulic circuit drawing part also includes instrument carrier with level gauge. This diploma thesis includes theoretical text part, technical report of designed objects, hydraulic calculations and drawing part.