Dissertations / Theses on the topic 'Hydraulic properties'

Laboratory experiments were conducted on vesicular basalt cores to estimate hydraulic properties. Properties included dry bulk density, effective porosity, skeletal density, saturated hydraulic conductivity and determination of moisture characteristic curves. Unsaturated hydraulic properties estimated included hydraulic conductivity and diffusivity as a function of matrix suction. Infiltration tests were run on a larger block of the same basalt. Infiltration curves were developed and saturated hydraulic conductivity estimated.

The term "lime" comes from the word limestone. Limestone rocks were converted to lime powder by burning (calcining). The process of converting limestone to lime was an old process and it has been well documented, archaeologically. It has been established that the production of lime is the oldest industrial process can"ied out by humankind, dating back thousands of years. In fact, 3650 years ago Moses instructed the people of Israel, after they crossed the Jordan River, to set up large stones and whitewash them with lime and write the laws of God in lime. Lime was the most commonly used cementatious binder until about a century ago, when its use started to decline. It was replaced by Portland cement, a material essentially developed for structural purposes in the era of the industrial revolution. Portland cement has certain advantages over lime. The material develops strength and hardens faster for work to be carried out at a greater pace with better quality control and agreed standards. It has now become the dominant cementitious binder, part of it due to aggressive marketing of the material by the manufacturers. The use of Portland cement in the restoration and conservation of old buildings and structures in the UK over the past few years has resulted in a series of problems and cost millions of Pounds to eradicate. The decline in the use of lime in many countries has not only caused a diminution of its production, but has also contributed to a gradual disappearance of the traditional skills required both to produce a high quality product and to use it in construction. Therefore it is necessary to reintroduce and revive the old tradition of using lime by providing more information about its production and use. At present there are no comprehensive standards or code of practices, British or European to aid engineers and contractors in the use of hydraulic and non hydraulic limes in construction. BS EN 459 (2001) gives guidance on the chemical and physical properties of limes but it does not provide vital information about lime-based mortars e.g. mix proportions, mixing process, bond with masonry units, curing methods and all other necessary aspects to assess in the use of the material in construction. At present it is very easy for engineers, contractors and consultants to misuse lime mortars in new construction or in restoration and conservation of old buildings. Part of the decline in production of lime and reluctance of use in construction is due to the lack of understanding of the material properties and its performance in structures. Therefore it is necessary to examine and revive the old tradition in using lime mortars in construction and look at the new technologies used presently in the production process in order to provide the necessary background and information to aid the use of the material The present study provides a literature review, test results, discussions, conclusions and background information to set up standards in the production and use of hydraulic and non-hydraulic limes and their mortars in the construction of new buildings and the restoration and conservation of old buildings. Hydraulic and non-hydraulic limes have an excellent track record in buildings through history but their use in the UK was missed for some thirty years or more. Part of the reason for undertaking this research programme was to examine the properties of pre-packaged hydraulic limes available in the market at present. The properties of limes vary considerably dependent on the raw materials, composition and manufacturing process. The results of this study showed that there was a great variation in the properties and performance of limes and their mortars. The results also showed that the properties of lime mortar improved by adding different percentages of POliland cement. The research examined the effect of sand grading on the lime mortars compreSSIve, splitting and brick/mortar bond strength. The thesis also investigated the effects of using different casting moulds and curing methods on mortar strength. The results showed that the porosity of lime mortar was one of the reasons it was a success in the past and why it was so important nowadays to use it in the restoration and conservation of historic buildings.

It has been the UK experience and many other countries throughout the world that our climate is changing. It is predicted that the UK climate will become warmer and wetter weather and the frequency of heavy rainfall events will increase. Rainfall can lead to dangerous driving conditions and may lead to deterioration of in-service performance of the materials used in road construction. This was the reason for the investigations reported in thesis that studied the rainfall-runoff characteristics of road surface materials.

A tomographic survey provides different coverages and perspectives on subsurface heterogeneity--incompletely overlapping information about the subsurface. Fusion of these pieces of information expands and enhances the capability of a conventional survey, provides cross-validation, and constrains inherently ill-posed field-scale inverse problems. In this study, we explore the possibility of using river stage variation for basin-scale subsurface tomographic surveys. Basin-scale tomography requires energy sources of great strengths; spatially and temporally varying natural stimuli are ideal energy sources for this purpose. Specifically, we use numerical models to simulate groundwater level changes in response to temporal and spatial variations of river stage in a hypothetical groundwater basin. We then exploit the relation between temporal and spatial variations of well hydrographs and river stage to image the heterogeneous characteristics of the basin.Next, we apply the hydraulic tomography testing technique and analysis algorithm to synthetic fractured media. The application aims to explore the potential utility of the technique and the algorithm for characterizing fracture zone distribution and their connectivity. Results of this investigation show that using hydraulic tomography with a limited number of wells can map satisfactorily the fracture zone distribution and the general pattern of its connectivity although estimated hydraulic property fields are smooth. As the number of wells and monitoring ports increases, the fracture zone distribution and connectivity becomes more vivid and the estimated hydraulic properties approach the true values.Further we develop a new parameter identification method that allows for simultaneous inclusion of all observed hydrographs from hydraulic tomography to map aquifer heterogeneity. A procedure is then recommended to diagnose and denoise observed hydrographs. Subsequently, we introduce methods that exploit these processed hydrographs for estimating effective parameters, boundary conditions, and statistical spatial structures of heterogeneity, which are the required inputs for the new hydraulic tomography analysis method. This new method and the data processing procedure are tested in a synthetic aquifer and subsequently applied to a sand box experiment. The estimated parameter fields for the sand box experiment are validated by predicting the head distribution induced by an independent pumping test, which was not used in the hydraulic tomography analysis.

Thesis (M.E.)--University of Florida, 1999.
Title from first page of PDF file. Document formatted into pages; contains x, 146 p.; also contains graphics. Vita. Includes bibliographical references (p. 141-145).

Both empirical and process-simulation models are useful for evaluating the effects of management practices on environmental quality and crop yield. The use of these models is limited, however, because they need many soil property values as input. The first step towards modelling is the collection of input data. Soil properties can be highly variable spatially and temporally, and measuring them is time-consuming and expensive. Efficient methods, which consider the uncertainty and cost of measurements, for estimating soil hydraulic properties form the main thrust of this study. Hydraulic properties are affected by other soil physical, and chemical properties, therefore it is possible to develop empirical relations to predict them. This idea quantified is called a pedotransfer function. Such functions may be global or restricted to a country or region. The different classification of particle-size fractions used in Australia compared with other countries presents a problem for the immediate adoption of exotic pedotransfer functions. A database of Australian soil hydraulic properties has been compiled. Pedotransfer functions for estimating water-retention and saturated hydraulic conductivity from particle size and bulk density for Australian soil are presented. Different approaches for deriving hydraulic transfer functions have been presented and compared. Published pedotransfer functions were also evaluated, generally they provide a satisfactory estimation of water retention and saturated hydraulic conductivity depending on the spatial scale and accuracy of prediction. Several pedotransfer functions were developed in this study to predict water retention and hydraulic conductivity. The pedotransfer functions developed here may predict adequately in large areas but for site-specific applications local calibration is needed. There is much uncertainty in the input data, and consequently the transfer functions can produce varied outputs. Uncertainty analysis is therefore needed. A general approach to quantifying uncertainty is to use Monte Carlo methods. By sampling repeatedly from the assumed probability distributions of the input variables and evaluating the response of the model the statistical distribution of the outputs can be estimated. A modified Latin hypercube method is presented for sampling joint multivariate probability distributions. This method is applied to quantify the uncertainties in pedotransfer functions of soil hydraulic properties. Hydraulic properties predicted using pedotransfer functions developed in this study are also used in a field soil-water model to analyze the uncertainties in the prediction of dynamic soil-water regimes. The use of the disc permeameter in the field conventionally requires the placement of a layer of sand in order to provide good contact between the soil surface and disc supply membrane. The effect of sand on water infiltration into the soil and on the estimate of sorptivity was investigated. A numerical study and a field experiment on heavy clay were conducted. Placement of sand significantly increased the cumulative infiltration but showed small differences in the infiltration rate. Estimation of sorptivity based on the Philip's two term algebraic model using different methods was also examined. The field experiment revealed that the error in infiltration measurement was proportional to the cumulative infiltration curve. Infiltration without placement of sand was considerably smaller because of the poor contact between the disc and soil surface. An inverse method for predicting soil hydraulic parameters from disc permeameter data has been developed. A numerical study showed that the inverse method is quite robust in identifying the hydraulic parameters. However application to field data showed that the estimated water retention curve is generally smaller than the one obtained in laboratory measurements. Nevertheless the estimated near-saturated hydraulic conductivity matched the analytical solution quite well. Th author believes that the inverse method can give a reasonable estimate of soil hydraulic parameters. Some experimental and theoretical problems were identified and discussed. A formal analysis was carried out to evaluate the efficiency of the different methods in predicting water retention and hydraulic conductivity. The analysis identified the contribution of individual source of measurement errors to the overall uncertainty. For single measurements, the inverse disc-permeameter analysis is economically more efficient than using pedotransfer functions or measuring hydraulic properties in the laboratory. However, given the large amount of spatial variation of soil hydraulic properties it is perhaps not surprising that lots of cheap and imprecise measurements, e.g. by hand texturing, are more efficient than a few expensive precise ones.

Both empirical and process-simulation models are useful for evaluating the effects of management practices on environmental quality and crop yield. The use of these models is limited, however, because they need many soil property values as input. The first step towards modelling is the collection of input data. Soil properties can be highly variable spatially and temporally, and measuring them is time-consuming and expensive. Efficient methods, which consider the uncertainty and cost of measurements, for estimating soil hydraulic properties form the main thrust of this study. Hydraulic properties are affected by other soil physical, and chemical properties, therefore it is possible to develop empirical relations to predict them. This idea quantified is called a pedotransfer function. Such functions may be global or restricted to a country or region. The different classification of particle-size fractions used in Australia compared with other countries presents a problem for the immediate adoption of exotic pedotransfer functions. A database of Australian soil hydraulic properties has been compiled. Pedotransfer functions for estimating water-retention and saturated hydraulic conductivity from particle size and bulk density for Australian soil are presented. Different approaches for deriving hydraulic transfer functions have been presented and compared. Published pedotransfer functions were also evaluated, generally they provide a satisfactory estimation of water retention and saturated hydraulic conductivity depending on the spatial scale and accuracy of prediction. Several pedotransfer functions were developed in this study to predict water retention and hydraulic conductivity. The pedotransfer functions developed here may predict adequately in large areas but for site-specific applications local calibration is needed. There is much uncertainty in the input data, and consequently the transfer functions can produce varied outputs. Uncertainty analysis is therefore needed. A general approach to quantifying uncertainty is to use Monte Carlo methods. By sampling repeatedly from the assumed probability distributions of the input variables and evaluating the response of the model the statistical distribution of the outputs can be estimated. A modified Latin hypercube method is presented for sampling joint multivariate probability distributions. This method is applied to quantify the uncertainties in pedotransfer functions of soil hydraulic properties. Hydraulic properties predicted using pedotransfer functions developed in this study are also used in a field soil-water model to analyze the uncertainties in the prediction of dynamic soil-water regimes. The use of the disc permeameter in the field conventionally requires the placement of a layer of sand in order to provide good contact between the soil surface and disc supply membrane. The effect of sand on water infiltration into the soil and on the estimate of sorptivity was investigated. A numerical study and a field experiment on heavy clay were conducted. Placement of sand significantly increased the cumulative infiltration but showed small differences in the infiltration rate. Estimation of sorptivity based on the Philip's two term algebraic model using different methods was also examined. The field experiment revealed that the error in infiltration measurement was proportional to the cumulative infiltration curve. Infiltration without placement of sand was considerably smaller because of the poor contact between the disc and soil surface. An inverse method for predicting soil hydraulic parameters from disc permeameter data has been developed. A numerical study showed that the inverse method is quite robust in identifying the hydraulic parameters. However application to field data showed that the estimated water retention curve is generally smaller than the one obtained in laboratory measurements. Nevertheless the estimated near-saturated hydraulic conductivity matched the analytical solution quite well. Th author believes that the inverse method can give a reasonable estimate of soil hydraulic parameters. Some experimental and theoretical problems were identified and discussed. A formal analysis was carried out to evaluate the efficiency of the different methods in predicting water retention and hydraulic conductivity. The analysis identified the contribution of individual source of measurement errors to the overall uncertainty. For single measurements, the inverse disc-permeameter analysis is economically more efficient than using pedotransfer functions or measuring hydraulic properties in the laboratory. However, given the large amount of spatial variation of soil hydraulic properties it is perhaps not surprising that lots of cheap and imprecise measurements, e.g. by hand texturing, are more efficient than a few expensive precise ones.

Subjects of this thesis were sampling and hydraulic properties of stony soils. Sampling is important to achieve knowledge of soil spatial variability. Soil surveys are generally time-consuming, labour-intensive and costly. This is especially true in stony soils where large numbers of samples are required to obtain a rappresentative sample size, and where sampling efforts are bigger than in non-stony soils. The potential use, of electromagnetic induction scans (EMI) to measure bulk electrical conductivity (EC) and improve the estimate precision of sparsely sampled primary variables, was assessed in a 5-ha gravelly soil vineyard in Valpolicella, North-Eastern Italy. EMI measurements were taken using a Geonics EM38DD operating in both horizontal and vertical mode. Geoelectrical investigations were also done in 18 positions with the electrical resistivity tomography (ERT) method in order to obtain high-resolution images of soil profile. The spatial variability of soil properties and their relationships with EC, in horizontal and vertical mode, was estimated by multivariate geostatistical techniques. There was generally close relationship between EC and the measured physical properties. The results proved that EM38DD could be advantageously used to infer soil spatial variability in gravelly soils, even if ground-truth soil samples are necessary to understand and interpret EC measurements. Hydraulic properties were studied by different approaches. Reconstructed samples were manually constructed using sieved clay soil and synthetic sand, as fine earth fraction, and glass spheres or cylinders, as coarse fraction. The choice to use the glass was to have a material which did not have any porosity, so it could be possible to evaluate the steric role of coarse fragment on soil hydraulic properties. Saturated hydraulic conductivity (Ks) measurements and evaporation experiments were conducted to determine hydraulic conductivity function and soil water retention characteristic. Ks values were compared with the theoretical approaches as literature describes. These approaches decrease the soil water content and hydraulic conductivity as stone content increases. Evaporation results were fitted by RETC to determine the van Genuchten-Mualem parameters. Nevertheless the observed high variability, results showed that coarse fragment effect on soil hydraulic properties has to be considered, both in terms of reduction of area for water flow and increase of the tortuosity, and as a factor which influences fine earth characteristics, determining a fine earth bulk density variation (bdfe). Saturated hydraulic conductivity measurements, evaporation experiments and mercury intrusion porosimetry analyses were conducted on undisturbed samples. Evaporation results were inverted by Hydrus 1D to estimate the van Genuchten-Mualem parameters. Correlation matrix showed stone positive effect on saturated hydraulic conductivity, which might be explained by the negative relationship between fine earth bulk density and coarse fragment content and by the positive relationship between coarse fragments and macro-porosity classes. Eighteen tension disc infiltration experiments were conducted in three soils of Regione Lombardia, Northern Italy. Soils were different for texture, stone content and organic matter content. Infitrometry experiments were used to determine the van-Genuchten-Mualem parameters by mean of Hydrus 2D/3D, used in parameter estimation mode. Some pedotransfer functions (PTFs) were used as multiple regression tool to better understand the effects of the analysed factors. Results showed high variability and it was not possible to clearly define the coarse fragment effect on soil hydraulic properties. PTFs showed, by the way, the importance of using the fine earth bulk density, both measured and estimated, to improve the estimation of saturated hydraulic conductivity. PEST-Hydrus 3D interface was used to determine the van Genuchten-Mualem parameters of the fine earth fraction (sieved clay), of some previously described reconstructed samples, on which evaporation experiments were conducted. Unsaturated hydraulic conductivity, as influenced by tortuosity, was determined by simulated infiltration events by Hydrus 3D, using different domains which contained different “empty spaces”, comparable to the coarse fragment content. Ksoil/Kfe ratio is normally used to determine hydraulic conductivity reduction in increasing coarse fragment content. Ksoil/Kfe was used to observe the stone positive effect on fine earth characteristics: it showed a tendency of increase of the hydraulic conductivity as stone content increased. Ksoil/Kfe ratio was also used to determine tortuosity effect: for the studied soils, there were not differences between cylinder and sphere effect on hydraulic conductivity. Moreover, it was observed that tortuosity effect decreased as matric potential, in absolute value, increased. Results proved that the theoretical approach used to determine the water content reduction in increasing coarse fragment content is a realistic estimation tool. Approaches used to determine hydraulic conductivity in increasing stone content should consider both the tortuosity effect and the fine earth bulk density variation as determined by the presence of coarse fragments.
In questo lavoro di tesi si sono approfondite tematiche legate al campionamento e alle proprietà idrauliche dei suoli scheletrici. Il campionamento è un aspetto fondamentale per conoscere la variabilità presente in un suolo. La capacità di descrivere dettagliatamente la realtà in esame è influenzata, oltre che dai mezzi tecnici utilizzati per effettuare il campionamento, anche dalla disponibilità in termini economici e di tempo. Nei suoli scheletrici tali limiti sono aumentati dalla maggiore quantità di suolo necessaria per ottenere un campione significativo e dalla maggiore difficoltà di campionamento rispetto ai suolo non scheletrici. Sul suolo di un vigneto di 5 ha in Valpolicella (VR) è stata valutata la possibilità di utilizzare strumenti ad induzione elettromagnetica (EMI) per misurare la conducibilità elettrica (EC) e la possibilità di tali strumenti di migliorare la stima di variabili primarie del suolo. Lo strumento impiegato per determinare EC è stato Geonics EM38DD, utilizzato sia in modalità orizzontale che verticale. Si sono inoltre condotte 18 tomografie di resistenza elettrica (ERT) al fine di ottenere immagini ad alta risoluzione del profilo del suolo. La variabilità spaziale delle proprietà del suolo e i valori di EC, orizzontali e verticali, è stata stimata utilizzando tecniche geostatistiche multivariate. In generale si è trovata una buona relazione tra EC e le proprietà fisiche misurate, dimostrando che EM38DD potrebbe essere utilizzato in modo vantaggioso per inferire la variabilità spaziale in suoli scheletrici, anche se rimane necessario il campionamento in campo per capire ed interpretare le misure di EC. Le proprietà idrauliche sono state analizzate utilizzando diversi approcci. Si sono innanzitutto ricostruiti dei campioni, utilizzando come terra fine un terreno argilloso e della sabbia sintetica, e sfere e cilindri di vetro come materiale grossolano. Il vetro è stato scelto in quanto rappresenta un materiale non poroso e adatto a studiare l’influenze sterica di tali materiali sulle caratteristiche idrauliche del suolo. Al fine di determinare la ritenzione idrica e la conducibilità idraulica insatura sono state effettuate delle misure di conducibilità idraulica satura (Ks) ed esperimenti evaporimetrici. I valori di Ks sono stati confrontati con gli approcci teorici presenti in letteratura. Questi prevedono una riduzione della ritenzione idrica e della conducibilità idraulica in funzione del contenuto di scheletro. I dati derivanti dagli esperimenti evaporimetrici sono stati interpolati utilizzando RETC per determinare i parametri del’equazione di van Genuchten-Mualem. Da tali prove, nonostante l’alta variabilità presente, è emerso che l’influenza del materiale grossolano sulle proprietà idrauliche deve essere considerata sia in termini di riduzione dell’area disponibile per il flusso di acqua e di tortuosità, sia come fattore che influenza le caratteristiche della terra fine, determinando una variazione della massa volumica apparente della stessa (bdfe). Misure di conducibilità satura, esperimenti evaporimetrici e analisi di porosimetria ad intrusione di mercurio sono stati condotti su campioni indisturbati. I dati evaporimetrici ottenuti sono stati analizzati utilizzando Hydrus 1D al fine di stimare i parametri dell’equazione di van Genuchten-Mualem. Da un’analisi di correlazione è emersa la positiva influenza dello scheletro sulla conducibilità satura, che è spiegabile dalla relazione negativa tra massa volumica apparente e lo scheletro stesso, e dalla relazione positiva tra scheletro e le classi più macroporose. Diciotto analisi di infiltrazione, utilizzando un infiltrometro a tensione, sono state condotte in tre siti lombardi, differenti per tessitura, contenuto in scheletro e sostanza organica. Gli esperimenti infiltrometrici sono stati modelizzati con Hydrus 2D/3D, permettendo di stimare i parametri dell’equazione di van Genuchten-Mualem. Alcune funzioni di pedotrasferimento (PTFs) sono state inoltre utilizzate come strumento di regressione multipla per meglio capire l’influenza dei diversi fattori analizzati. La variabilità presente è risultata elevata, e non si è potuta determinare in modo chiaro l’influenza del solo scheletro sulle caratteristiche idrauliche. PTFs hanno, comunque, permesso di evidenziare l’importanza di utilizzare la densità apparente della terra fine, misurata o stimata, come fattore che migliora la capacità predittiva per la determinazione della conducibilità idraulica satura. Utilizzando PEST-Hydrus 3D è stato possibile determinare i parametri dell’equazione di van Genuchten-Mualem della sola terra fine, di alcuni dei campioni ricostruiti descritti in precedenza, su cui si erano condotti esperimenti evaporimetrici. Effettuando simulazioni di infiltrazione in Hydrus 3D, utilizzando domini a differente contenuto di “spazi vuoti”, assimilabili al contentuto di scheletro, si è inoltre determinato il comportamento della conducibilità idraulica insatura in funzione della tortuosità. Utilizzando Ksoil/Kfe, rapporto che è normalmente utilizzato per determinare la riduzione della conducibilità in funzione del contenuto di scheletro, si è potuto osservare la positiva influenza dello scheletro sulle caratteristiche della terra fine, evidenziando una tendenza all’aumento della conducibilità all’aumentare del contenuto di scheletro. Lo stesso approccio è stato utilizzato per determinare l’influenza della tortuosità: per i suoli studiati non sono emerse differenze tra l’influenza dei cilindri e delle sfere su questo parametro e si è osservato che l’incidenza della tortuosità decresce all’aumentare, in valore assoluto, del potenziale matriciale. Dai risultati ottenuti è un approccio realistico ipotizzare che in un suolo, mantenendo costanti le caratteristiche della terra fine, diminusca la ritenzione idrica in funzione dell’aumento del contenuto di scheletro su base volumetrica. Gli approcci utilizzati per determinare della conducibilità idraulica all’aumentare dello scheletro dovrebbero considerare, oltre all’influenza delle tortuosità, anche la variazione di massa volumica apparente della terra fine determinata dalla presenza dello scheletro stesso.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O presente trabalho de pesquisa teve dois objetivos principais. O primeiro foi obter um índice geotécnico que permita avaliar o grau de intemperismo dos solos residuais. Para isto foram analisados dados correspondentes a perfis de alteração de Gnaisse característicos do município do Rio de Janeiro e executou-se a caracterização completa de um perfil específico de alteração de Gnaisse Facoidal. O segundo objetivo foi a determinação experimental das propriedades hidráulicas de solos tropicais não saturados. Como parte deste objetivo foram desenvolvidos novos instrumentos e modificados equipamentos existentes. A determinação da curva característica de sucção foi efetuada em seis solos residuais e em dois solos sedimentares. Na obtenção das curvas de retenção foram utilizadas as técnicas de translação de eixos, papel filtro e umidade relativa. Esta curva foi também definida a partir de resultados de ensaios de porosimetria de mercúrio. Avaliou-se a aplicabilidade dos modelos disponíveis na literatura no ajuste dos dados experimentais. A função de permeabilidade foi determinada em dois solos, um residual e um sedimentar, utilizando um permeâmetro de parede flexível com sucção controlada. Análises numéricas, efetuadas para avaliar o comportamento do equipamento utilizado, possibilitaram a definição de uma metodologia otimizada de interpretação dos resultados. A aplicabilidade dos modelos disponíveis na literatura na obtenção da função de permeabilidade foi analisada, tendo-se verificado a necessidade de introdução de mudanças nestas formulações para se conseguir reproduzir as medidas diretas efetuadas.
The present research work had two main objectives. The first was to obtain a geotechnical index for measuring the weathering degree of gneissic residual soils. For that it were analyzed data corresponding to typical weathering profiles found in the municipality of Rio de Janeiro and executed a complete characterization of a specific weathering profile of facoidal gneiss. The second objective was to determine, experimentally, the hydraulic properties of tropical unsaturated soils. As part of that new instruments were developed and existing equipments were modified. Moisture retention curves were determined for six residual soils and two sedimentary ones. The axis- translation technique, the filter paper method and the relative humidity one were employed to obtain such curves. Data from mercury intrusion porosimetry tests were also used to define these curves. The applicability of models available in literature to adjust the obtained experimental data was evaluated. The hydraulic conductivity function was determined for two soils, one residual and one sedimentary. A suction controlled, flexible wall permeameter set up was used for that. Numerical modeling was implemented to evaluate the performance of the experimental set up. This provided means for an optimized interpretation of the testing results. The applicability of models available in the literature to obtain the permeability functions was evaluated, being found the need to introduce changes in their formulation in order to be able to reproduce the obtained experimental data.

As plant roots grow through the soil, the hydraulic properties of the adjacent soil may change and be altered through the release of exudates and mucilage or through the re- arrangement of soil particles. Though these two possible mechanisms have been identified in the literature, the published work has not distinguished whether the change in water release and sorption are due to the mucilage affecting surface tension and/or contact angle or if the growing root re-arranges the soil particles so that there is less pore space that can hold water. In this thesis the effect of mucilage and particle re-arrangement on rate of inltration and water release has been studied. First, the effect of mucilage and particle re-arrangement on rate of inltration of water was investigated. Wheat, maize and barley plants were grown in silty loam cores. The results illustrated significant differences between these plant species grown in the soil cores. More importantly when maize seedlings were grown in sandy soil rhizoboxes the rhizosphere and bulk soil were significantly different, with the sorption rate being greater for the bulk soil. To explain these differences the impact of both soil density changes and mucilage on inltration in soil were studied. The lower density was significantly different compared with the higher density, with the lower having a greater sorption rate. There was no effect of mucilage on inltration but there were significant differences between the sorption rate at different time intervals. The effect of mucilage and particle re-arrangement on water release was investigated using rhizosphere and bulk aggregates and soil from plastic rings. The water content of rhizosphere soil was not significantly different from that for the bulk soil at saturation, suggesting that roots had no effect on the porosity of the soil. However the water content of the rhizosphere soil for maize and barley was significantly lower (P<0.05) at a pore water pressure of -0.15 kPa. The capillary fringe in glass capillaries using deionised water and natural mucilage was measured and it was found that mucilage decreased the capillary fringe to 0.7 of that for pure water. However application of this value to the bulk soil water release characteristic did not account for the changes observed in the water release characteristic for the rhizosphere soil. Possible explanations for the results from the sorption and water release experiments include wetting and drying, change in contact angle and surface tension by mucilage, particle re-arrangement increasing soil density, and microbes altering mucilage concentrations. It is concluded that the re-arrangement of soil particles by roots was found to be more important than the changes caused by the release of mucilage in affecting the hydraulic properties of the soil.

A finite-element model was developed to simulate the water flow underneath a surface point source using the Galerkin method of weighted residuals and the mixed formulation of the Richards' equation. The saturated radius usually formed during a point source test was estimated by the numerical model. Comparisons with published experimental and analytical results indicated that the model is accurate and reliable. The numerical model aids in understanding the water regime under different point source scenarios. The finite element model was coded in C++ by using an object oriented approach. This allows flexibility for future updating. Finite and infinite elements were combined to obtain a numerical solution for unbounded 1-D flow domains. The results showed that the use of infinite elements may reduce the computational time when solving the flow equations for deep profiles. Although the transient point-source problem can be solved numerically, generalized solutions were developed and their coefficients calculated by best fitting numerical results of dimensionless saturated radius and time. The solutions allow calculation of the transient saturated radius given values of the van Genuchten hydraulic function parameter "m" and dimensionless point-source application rate. The resulting generalized solutions have the advantage of reducing large volumes of data. The estimation of soil hydraulic parameters from field data by using existing flow theory is analyzed. The results obtained from these studies verified that soil type and conditions can limit field estimation of steady state data for some soils. As a consequence, estimation of steady data is highly recommended by fitting field data to empirical equations. An empirical equation for transient saturated radius as a function of time was proposed. This equation is robust to predict steady-state saturated radius. To test the applicability of point source tests, hydraulic properties were estimated from field disc and point source tests. The parameters obtained from the disc and point-source methods matched closely. An overall methodology is also given for conducting point-source tests.

Research findings in current study provide a new insight into the fractured rock aquifers in the TMG area. Some of the results will have wide implications on the groundwater management and forms a solid basis the further study of the TMG aquifers.

Hence hydraulic fluid is the medium of power transfer in hydraulic equipment, it is important to know the properties of hydraulic fluids and its influence on system performance. There are different types of fluids based on their availability, working purpose etc. So selection of fluid depends on the working conditions of the hydraulic equipment. So to select a fluid one has to be clear about the operating conditions of hydraulic equipment and this can be achieved by testing the equipment with different fluids and select the fluid that gives the best performance. To know about the properties (like Viscosity, operating temperature range) of fluids available there should be some standardisation of hydraulic fluids and one such type is ISO (International organization for standardization). Though there are many this is followed by most. By this standardization the fluid manufacturer can categorize the fluids and the user can easily select the fluid according to their requirement. The thesis work mainly deals with two parts. First part is giving a brief description of fluids based on ISO standards and standard test methods for hydraulic systems. The major or second part deals with finding the performance of six different types of fluids from four different manufacturers. Among them five fluids are environmentally acceptable hydraulic fluids and one is mineral oil based hydraulic fluid. The main task is to find the performance of this five environmentally acceptable hydraulic fluids comparing with standard mineral oil so that it will be useful for the equipment manufacturers to select a fluid for the system. The other main task of the thesis is to measure the pressure losses in long hoses which are used in forest machines. So a test plan was made to cover both the tasks, where the test method to find the losses in hose is one of the test method in finding the performances of the six fluids. The procedure about the tests are clearly explained in section 5.1. Among the five environmentally acceptable hydraulic fluids one is synthetic bio diesel and remaining four are synthetic ester based fluids and standard mineral oil is paraffin based. Because of the confidentiality the fluid names has been changed based on their viscosity as diesel oil (synthetic bio diesel), synth 32, synth e 32, synth es 32, synth 12 and mineral oil 46 (standard mineral oil). Synth e 32 and synth es 32 are the upgraded fluids of synth 32 fluid from same manufacturer.

Rotational hydraulic actuators, e.g. motors, provide infinite stroke as there is no conceptual limit to how far they can turn. By contrast linear hydraulic actuators like cylinders provide only limited stroke by concept. In the world of electrical drives, linear motors provide infinite stroke also for linear motion. In hydraulics, the presented Hydraulic Infinite Linear Actuator is a novelty. This paper presents the novel Hydraulic Infinite Linear Actuator (HILA). The contribution is an assessment of properties relevant for control like high hydraulic stiffness and is based on analysis, simulation and measurements.

The main objective of this work is to model granular materials comprising particles of as pherical shape and investigate the effect of the grain shape on the hydraulic properties of the material. For this purpose, a Discrete Element Method code for clustered spheres was developed during the course of this work to simulate aspherical particles. The shape of the particles modelled mimics the morphology of real grains obtained from a shape library of real scanned particles for which development this thesis also contributed. The simulation tools are then used to construct models of real sands by simulating the settling under gravity and compaction of the grains. The hydraulic properties of the sand moels are then investigated via numerical simulations using two different approaches. First, we simulate low Reynolds numbers flow in granular packs using a Finite Element method within the Stokes flow approximation. Then we explore the applicability of the two-fluids approach to simulate fluid flow in the presence of solid obstacles and complex microstructures. By integrating the technologies developed during this work, it was possible to simulate the single phase flow in a wide range of Reynolds number in models of sand. The results obtained closely agree with available experimental data and empirical correlations for relatively clean and homogeneous sands. These results show that the hydraulic permeability can vary within a factor of two as a consequence of the particle shape. This indicates that for unconsolidated media the most important parameter with regards to fluid flow conductivity is the porosity.

Coal provides for 77% of South Africa&rsquo
s primary energy needs and is therefore a major resource that supports the socio-economic needs of South African citizens. Power stations are the major consumers of coal in South Africa and produces electricity from burned coal. The burning of coal produces a large volume of ash that is disposed in the form of ash dump systems. The ash 
dump system is treated with high salinity process water from the power station for dust suppression. The process water contains salts due to evaporation processes from the recirculation 
 
of 
water in the cooling water system. Various studies to evaluate the sustainability of the ash dump system as a sustainable salt sink were therefore conducted. This study aimed to develop a conceptual model for the ash dump system by evaluating the movement of the process water trough the ash dump and the impacts it might have on the underlying weathered dolerite aquifer. This was achieved by evaluating the hydraulic and transport properties of the ash dump system. An initial site conceptual model was first established prior to the application of the hydraulic 
and transport methods. The initial conceptual model was based on the literature, previous reports and an initial site walk over. Known and tested hydraulic and transport methods were applied 
n bo.th field and laboratory scale for the saturated part of the ash dump system. The laboratory experiments comprised of column and core experiments. These methods assisted in 
parameter estimation of hydraulic and transport properties and also assisted in the planning of the field experiments. The field experiments were conducted in the form of slug tests, tracer 
dilution and natural gradient divergent tracer test experiments. The combined laboratory and field experiments provided statistically significant values that were then used as inputs into the 
conceptual model. Field experiments were also applied to a surrogate aquifer that represented the underlying shallow weathered dolerite aquifer of the ash dump system. The components of 
the updated conceptual model identified and investigated include the physical environment, the calculated hydraulic and transport properties.The ash dump can be conceptualized as a 20 to 
 
30 meter high heap of consolidated clay size ash 
particles built on top of an underlying shallow weathered dolerite aquifer. The ash dup is directly connected to the underlying weathered 
dolerite aquifer. The saline water within the saturated zone has the ability to move through the ash dump system with hydraulic conductivities ranging between 10-1-10- 2 m/day, with flow 
velocities of 7-8m/day and effective porosities of 1%-2%. The hydraulic properties of the ash dump are, amongst others, controlled by the ash geology, contact time of the process water with the 
sh and show a significant reduction in hydraulic conductivity over time, before reaching a steady state. The transport properties are controlled by advection and spreading in available 
pathways. Results for the surrogate underlying fractured rock aquifer show flow velocities of 31m/day and an effective porosity of 1%.This suggests that the underlying weathered dolerite 
aquifer is vulnerable to process water contamination from the ash dump system. The study illustrates the importance of a site conceptual model before the application of investigative 
methods. Hence having a site conceptual model provides an excellent platform for hydraulic and transport estimation. The development of a site conceptual model enhanced the 
understanding of flow and transport movement of the processed 
water trough the ash dump, it also assisted as a beneficial tool to enhance ash dump management.

This dissertation focuses mainly on three topics: (1) mixed-mode branching and segmentation of hydraulic fractures in brittle materials, (2) hydraulic fracture propagation in particulate materials, and (3) hydraulic fracturing in water flooding conditions. Mixed-mode loading is one of the primary causes of fracture branching and segmentation in brittle materials. We conducted the first laboratory experiments on the mixed mode I+III hydraulic fracturing. We found that a KIII/KI ratio as small as ~1% is sufficient for fracture front segmentation. In reality, such a small mode III component is always expected, for example, due to the small deviations of the fracture shape from planar. Thus, we concluded that fracture segmentation is likely to accompany growth of most, if not all, real hydraulic fractures. We also proposed a theoretical model that captures the main features of experimental observations and indicates the importance of the hydraulic effect of segmentation. Particulate materials often exhibit pronounced non-linear behavior and yielding even at relatively small loads. In order to adequately describe hydraulic fracturing in particulate materials with low or no cohesion, plasticity at the crack tip must be explicitly considered. We investigated the shear band mechanism of strain localization at the fracture front. This mechanism takes into account the fact that cohesionless material can not bear tension, and is in compression everywhere, including near the fracture front. To verify the shear band hypothesis, we conducted numerical simulations of the plastic deformation at the tip of a fracture in particulate material with strain softening. Our model describes the shear bands by properly placed and oriented dislocations. The model results are consistent with experimental observations. Water flooding, which in certain important cases, can result in processes resembly hydraulic fracturing by a low-viscosity fluid with extremely high leak-off. It is difficult to simulate this process in the laboratory. To investigate the fracture initiation mechanism in water flooding conditions, we conducted a numerical simulation of fluid injection into particulate material by using the discrete element code PFC2D. We also considered an analytical model of cavity initiation based on the fluidization mechanism. The estimates given by this model fit remarkably well with the numerical simulation results.

The purpose of this study was to determine the unsaturated hydraulic properties of High Level Waste simulant by applying inverse modeling and parameter estimation methods and data obtained by experiments. Saltcake simulant was placed in column equipped with tensiometers and flow meters. Variable pressure boundary conditions ranging from 100 to 500 cm were applied along the column, outflow and the pressure head were measured with respect to time. The experimental data was analyzed using an inverse modeling software and the van Genuchten's hydraulic parameters for unsaturated porous media were determined. In addition, the unsaturated hydraulic conductivities were obtained as a function of the moisture content. Hydraulic conductivities ranged from 5.36E-5 to 4.29E-2 cm/hr. The data was analyzed to determine the percentage reduction in storage capacity as a function of applied pressure. The experimental results were compared with output from direct simulations of interstitial fluid drainage from a column and showed good agreement. While there are several studies on determining the saturated hydraulic conductivities, this work demonstrates that the van Genuchten unsaturated model is a valid model and can be applied for three dimensional modeling and for determining the level of separation of radioactive waste (Cs 137) using interstitial fluid drainage.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A cidade do Rio de Janeiro apresenta relevo acidentado e clima tropical. Os processos intempéricos que ocorrem na litologia geram os solos residuais e coluvionares. Tendo em vista a limitação espacial de áreas planas, a ocupação antrópica se direciona as áreas de encosta, onde estes solos estão presentes. Ao longo dos anos tem-se estudado que a maioria dos movimentos de massa da cidade do Rio de Janeiro estão relacionados à perda de sucção mátrica do solo. O presente trabalho visa, portanto, a obtenção de parâmetros hidráulicos dos solos não-saturados de maneira simples, rápida e pouco onerosa a fim de viabilizar estudos da infiltração de água em taludes. Para isso, foram estudadas 6 áreas ao longo do Rio de Janeiro, onde a escolha se baseou.na rocha de origem formadora dos solos residuais. Os ensaios do trabalho utilizados foram o Ensaio de Infiltração Monitorada (EIM) e caracterização física, e para efeitos comparativos também foram executados alguns ensaios de Guelph, papel filtro e permeabilidade saturada triaxial. O modelo de interpretação não-saturado usado foi o modelo de van Genutchen-Maulem, e a obtenção de três dos cinco parâmetros foi feita através de uma análise inversa. A curva a ser retroanalisada no ensaio é a série temporal da sucção mátrica.
Rio de Janeiro city is sited on a rugged relief and has a tropical climate. The meteoric processes that take place on its lithology generate the residual and transported soils. Accounting for its limited flat urban space, its habitants tend to live in steep slope areas where such soils are present. For a long time studies have taken place to characterize mass movements and their conclusions relate most of them to the loss of soils matric suction. Therefore the study aims to obtain the unsaturated soil parameters in a simple, rapid and low cost way, which may help future studies of water infiltration on slopes. And thus, 6 locations in Rio de Janeiro were choosen based on the criteria of soil formation, attending different types of gneissic bedrocks. The constitutive model used was the van Genuchten and the method to obtain three of its five parameters was by solving an inverse problem. The curve to be optimized comes from the monitored infiltration test which consists on the record of the matric suction over a constant head infiltration test.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第7873号
農博第1031号
新制||農||775(附属図書館)
学位論文||H11||N3236(農学部図書室)
UT51-99-G467
京都大学大学院農学研究科森林科学専攻
(主査)教授 水山 高久, 教授 三野 徹, 教授 吉田 博宣
学位規則第4条第1項該当

Thesis (M.S.)--West Virginia University, 1999.
Title from document title page. Document formatted into pages; contains xiii, 132 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 98).

This dissertation presents studies on several statistical-mechanical problems, many of which involve exotic many-particle systems. In Chapter 2, we present an algorithm to generate Random Sequential Addition (RSA) packings of hard hyperspheres at the infinite-time saturation limit, and investigate this limit with unprecedented precision. In Chapter 3, we study the problem of devising smooth, short-ranged isotropic pair potentials such that their ground state is an unusual targeted crystalline structure. We present a new algorithm to do so, and demonstrate its capability by targeting several singular structures that were not known to be achievable as ground states with isotropic interactions.

A substantial portion of this dissertation examines exotic many-particle systems with so-called “collective-coordinate” interactions. They include “stealthy” potentials, which are isotropic pair potentials with disordered and infinitely degenerate ground states as well as “perfect-glass” interactions, which have up to four-body contributions, and possess disordered and unique ground states, up to trivial symmetry operations. Chapters 4-7 study the classical ground states of “stealthy” potentials. We establish a numerical means to sample these infinitely-degenerate ground states in Chapter 4 and study exotic “stacked-slider” phases that arise at suitable low densities in Chapter 5. In Chapters 6 and 7, we investigate several geometrical and physical properties of stealthy systems. Chapter 8 studies lattice-gas systems with the same stealthy potentials. Chapter 9 is concerned with the introduction and study of the perfect-glass paradigm. Chapter 10 demonstrates that perfect-glass interactions indeed possess disordered and unique classical ground states—a highly counterintuitive proposition.

In Chapter 11, we use statistical-mechanical methods to characterize the spatial distribution of the prime numbers. We show that the primes are much more ordered than anyone previously thought via the structure factor. Indeed, they are characterized by infinitely many Bragg peaks in any non-zero interval of wave vectors, yet unlike quasicrystals, the ratio between the heights or locations of any two Bragg peaks is always rational. We analytically explain the locations and heights of all such peaks.

[Truncated abstract] Root-induced changes to soil hydraulic properties (SHP) are an essential component in understanding the hydrology of an ecosystem, and the resilience of these to climate change. However, at present our capacity to predict how roots will modify SHP and the consequences of this is limited because our knowledge of the processes and effects are highly fragmented. Also, current models used to investigate the relationship between plants and root-induced changes to SHP are based on empirical relationships which have limited applicability to the various and often contrasting ecosystems that occur. This thesis focuses specifically on the quantifying the processes by which roots modify SHP and developing models that can predict changes to these and the water balance. Both increase and decreases in saturated hydraulic conductivity have been attributed to the presence of roots. In general, decreases occur when the root system is relatively young, and increases occur when the roots senesce and begin to decay, creating voids for water flow. The evidence available suggests that the change in pore geometry created by roots is the dominant process by which roots modify SHP because they are more permanent and of a greater magnitude than changes to fluid properties or soil structure. We first quantified the effects of wheat roots on SHP of a coarse sand with a laboratory experiment where we measured changes in both SHP and the root system at 3, 5, 7 and 9 weeks after sowing (weeks). ... The main message that can be drawn from this thesis is that root-induced changes to SHP are dynamic, and dependent upon the combination of soil texture, connectivity of root-modified pores and the ratio of root radius to pore radius. Consequently, root-induced changes to the water balance have the same dependencies. The work in this thesis provides a significant first step towards improving our capacity to predict how roots modify soil hydraulic properties. By defining the range for the parameters used to predict how the soil is modified by roots, we are able to make quantitative assessments of how a property such as hydraulic conductivity will change for a realistic circumstance. Also , for the first time we have measured changes in soil hydraulic properties and roots and have been able to establish why a rapid change from a root-induced decrease to increase in Ks occurred. The link between physiological stage of the root system, and the changes that are likely to occur has implications for understanding how roots modify SHP: it may provide an effective tool for predicting when the switch from a decrease to increase occurs. Further work is required to test the validity of the assumptions we have made in our models that predict changes to SHP. While we have endeavoured to define the parameter space for those parameters that we have introduced, there is still some uncertainty about the connectivity of root-modified pores. Also, the parameterisation of the soil domain with roots is based upon work that measures 'fine' roots only which may not provide a true representation of the effect trees and perennial shrubs have on SHP. It is inevitable that root-induced changes to SHP will affect the fate of solutes in the soil, and temporal dynamics of root-induced changes to these may be particularly important for the timing of nutrient and pesticide leaching.

Mass and energy flow processes in soil are strongly dependent on the state of the soil structure and on pore space geometry. To correctly describe these transport processes, an adequate pore space characterization is required. In this context, the use of computerized microtomography allows the visualization of the soil structures and processes that occur at large scales may be very useful, besides being a fast and non-destructive technique. Soil hydraulic properties, which are essential in the quantification of water balance components in hydrological models of the unsaturated zone, can be measured directly with field or laboratory methods. Simultaneous determination of these properties can be done by the Wind-Schindler evaporation method, but determining only the retention function is a more common practice. The relation between soil water retention and hydraulic conductivity can then be predicted using theories like those developed by Childs and Collis-George, Burdine and Mualem. These models treat pore-space tortuosity and connectivity as an empirical parameter, and its value remains usually undetermined, the use of a standard value being more common. Based on this contextualization, the objectives of this thesis are: (i) to evaluate the correlation between soil hydraulic properties measured in the laboratory, and parameters that quantify soil pore space from 3D images obtained by X-ray microtomography; and (ii) to functionally analyze soil hydraulic property parameterization in the prediction of soil water balance components by an agrohydrological model. To verify the relationship between soil hydraulic properties and soil image parameters, a stepwise multiple regression analysis was performed between the pore space parameters from images and empirical parameters of the semi-deterministic model, obtained with evaporation experiments together with an inverse solution method. Functional evaluation of soil hydraulic parameters was performed by a sensitivity analysis of the outputs of an agro-hydrological model to several ways of obtaining the tortuosity/connectivity parameter: applying the commonly used standard value, or determining its value in evaporation experiments in the laboratory with wet-range tensiometers, dry-range tensiometers, or both wet- and dry-range tensiometers. Simulations with the agro-hydrological model were performed for some years with distinct rainfall characteristics. The soil retention curve obtained using soil images had a good agreement to the retention curve obtained by the evaporation experiment, although the spatial resolution of the microtomograph allowed to only quantify macropores, consequently, to determine the hydraulic properties in a small range close to saturation. Soil hydraulic parameterization using a wide range of pressure heads is recommended for a better representation of vadose zone processes and soil-water-plant relations
Os processos de fluxo de massa e energia no solo dependem fortemente do estado da estrutura do solo e da geometria do espaço dos poros. Para descrever corretamente esses processos de transporte, é necessária uma caracterização adequada do espaço poroso. Neste contexto, o uso da microtomografia computadorizada permite a visualização das estruturas do solo e os processos que ocorrem em grandes escalas podem ser muito úteis, além de ser uma técnica rápida e não destrutiva. As propriedades hidráulicas do solo, que são essenciais na quantificação dos componentes do balanço hídrico em modelos hidrológicos da zona não saturada, podem ser medidas diretamente com métodos de campo ou laboratório. A determinação simultânea dessas propriedades pode ser feita pelo método de evaporação Wind-Schindler, mas a determinação apenas da função de retenção é uma prática mais comum. A relação entre a retenção de água do solo e a condutividade hidráulica pode então ser predita por teorias como as desenvolvidas por Childs e Collis-George, Burdine e Mualem. Esses modelos tratam a tortuosidade e conectividade do espaço poroso como um parâmetro empírico, e seu valor permanece geralmente indeterminado, sendo o uso de um valor padrão mais comum. Com base nessa contextualização, os objetivos desta tese são: (i) avaliação da correlação entre propriedades hidráulicas do solo, medidas em laboratório e parâmetros que quantificam o espaço de poros do solo a partir de imagens 3D obtidas por microtomografia de raios X; (ii) a análise funcional da parametrização das propriedades hidráulicas do solo na predição dos componentes do balanço hídrico do solo por um modelo agro-hidrológico. Para a verificação da relação entre as propriedades hidráulicas do solo e os parâmetros da imagem do solo, foi realizada uma análise de regressão múltipla entre os parâmetros do espaço poroso por imagens e parâmetros empíricos do modelo semi-determinística, obtidos com experimentos de evaporação juntamente com método de solução inversa. A avaliação funcional das parametrizações hidráulicas do solo foi feita pela análise de a sensibilidade das saídas de um modelo agro-hidrológico a várias maneiras de obter o parâmetro de tortuosidade/conectividade: aplicando um valor fixo comumente utilizado ou determinando seu valor em experimentos de evaporação no laboratório com tensiômetros na faixa úmida, tensiômetros na faixa seca, ou com tensiômetros nas faixas seca e úmida. As simulações com o modelo agro-hidrológico foram realizadas por vários anos com disponibilidade de água distinta. A curva de retenção de solo obtida através de imagens do solo está em concordância com a curva de retenção obtida pelo experimento de evaporação, embora a limitação da resolução espacial da microtomografia, permitiu apenas quantificar macroporos, consequentemente, a determinação das propriedades hidráulicas em uma pequena faixa próxima à saturação. A parametrização hidráulica do solo usando uma faixa mais ampla de tensões é recomendada para melhor representar os processos na zona não-saturada e das relações solo-água-planta

Effect of joint geometry parameters and joint transmissivity on the hydraulic properties of jointed rock including the equivalent permeability tensor is investigated through a series of numerical experiments. The equivalent continuum hydraulic behavior of jointed rock was found to be sensitive to the orientation of the joint sets in a joint network system. The chances for the equivalent continuum behaviour were found to increase with the increase of joint density and joint size. It was found that for some joint systems, the equivalent continuum behavior does not exist irrespective of the rock block size; joint systems with low orientation angles, low joint densities and small joint sizes seem to have chance belonging to this category. The equivalent continuum behavior of a joint system can be expressed with respect to a cut-off value for the first invariant of fracture tensor (F0). If the F0 value for a given joint network is more than the cut-off value, then the joint system can be approximated by an equivalent continuum. For the joint systems investigated in this study, values between 10 and 30 were found for cut-off F0. A threshold value of F0 between 3 and 6 was found to achieve a non-zero average block permeability (K0). Both the threshold value and the cut-off value of F0 were found to depend on the relative orientations of joint sets. Chances to reach equivalent continuum behavior for a rock mass having a certain joint configuration increases with the increase of block size. REV size for a joint system was found to depend on the orientation of the joint sets and on the distribution of joint size and density. REV size seems to decrease with increasing joint density. The block size corresponding to the aforementioned cut-off F0 can be considered to provide the REV size for a given joint configuration. For a considered joint network, K0 increases with the increase of block size until the block size is equal to REV size. The K0 value at the REV size for a joint system increases with increase in joint size and joint density. The relation between K0 and F0 seems to depend on the relative orientation of the joint sets in the joint network. Joint hydraulic conductivity plays a major role on the equivalent continuum behaviour and permeability anisotropy. A non linear relation seems to exist between the directional permeability and the fracture tensor component for the connected joint configuration when rock blocks contain minor discontinuities. For rock blocks containing major discontinuities this relation becomes linear.

The design and construction of large $1.2$~$m$ diameter lysimeters has been implemented to monitor the soil water retention behaviour and permeability characteristics of contaminated soils under remediation. The work was carried out as part of a larger project focussing on the sustainable remediation of low value brownfield land. Three lysimeters have been filled with lead contaminated soil: one control; one with a \ac{WTR} amendment; and one with a \ac{WTR} and compost amendment. A new software system was built to control the \ac{TDR} point water content measurement and irrigation system, which could log data to an online unified data repository; provided an interface for connectivity to any serial port device; deal with templating for simplified setup; and realtime feedback for the end user. High capacity tensiometers were used in conjunction with the \ac{TDR} point water content measurement system to read volumetric water contents and suctions in the large control lysimeter over a series of wetting and drying cycles, each lasting several months. The results demonstrate that there was a difference between small scale laboratory tests and the data obtained from the lysimeters, particularly in the near surface soil due to cracking. Where cracking was not present, the agreement was stronger, but differences suggested that the drying curves in the lysimeter was predominantly scanning behaviour whereas the element tests were likely more representative of primary drying behaviour.

Improving agricultural water management is important for conserving water during dry seasons, using limited water resources in the most efficient way, and minimizing environmental risks (e.g., leaching, surface runoff). The understanding of water movement in different zones of agricultural production fields is crucial to developing an effective irrigation strategy. This work centered on optimizing field water management by characterizing the spatial patterns of soil hydraulic properties. Soil hydraulic conductivity was measured across different zones in a farmer’s field, and its spatial variability was investigated by using geostatistical techniques. Since direct measurement of hydraulic conductivity is time-consuming and arduous, pedo-transfer functions (PTFs) have been developed to estimate hydraulic conductivity indirectly through more easily measurable soil properties. Due to ignoring soil structural information and spatial covariance between soil variables, PTFs often perform unsatisfactorily when field-scale estimations of hydraulic conductivity are needed. The performance of PTFs in estimating hydraulic conductivity in the field was therefore critically evaluated. Due to the presence of structural macro-pores, saturated hydraulic conductivity (Ks) showed high spatial heterogeneity, and this variability was not captured by texture-dominated PTF estimates. However, the general spatial pattern of near-saturated hydraulic conductivity can still be reasonably generated by PTF estimates. Therefore, the hydraulic conductivity maps based on PTF estimates should be evaluated carefully and handled with caution. Recognizing the significant contribution of macro-pores to saturated water flow, PTFs were further improved by including soil macro-porosity and were proven to perform much better in estimating Ks compared with established PTFs tested in this study. Additionally, the spatial relationship between hydraulic conductivity and its potential influencing factors were further quantified by the state-space approach. State-space models outperformed current PTFs and effectively described the spatial characteristics of hydraulic conductivity in the studied field. These findings provided a basis for modeling water/solute transport in the vadose zone, and sitespecific water management.

One of the most relevant issues in groundwater hydrology is the assessment of heterogeneous hydraulic properties of natural aquifers at the intermediate scale. The intermediate scale includes, as a general definition, aquifers characterized by a ratio L/B, L being a linear measure of the horizontal extent, and B the average thickness, between one (local scale) and approximately one thousand (regional scale). In Italy groundwater represents almost eighty percent of drinkable water supply, therefore the control of groundwater pollution as well as an optimal planning of the well production activity are essential steps in groundwater management that are generally developed at the intermediate scale. The assessment of unknown geological properties affecting groundwater dynamics and the quantification of the related uncertainty is thus one of the most relevant issues, known in literature as parameter estimation or inverse modelling. Regional and local scales have been largely studied by the scientific community, although the local scale is typically less exploited than the regional. The intermediate scale, instead, has been the subject of a relatively limited number of publications and is still characterized by relevant open problems, like, for example, the optimal choice of the numerical model to adopt or the definition of a proper parameter estimation approach. Moreover, a limit is often given by the lack of experimental sites available for testing the new research developments. As a result, too often the research is not applied in real-world problems. This thesis is subdivided in four chapters. In Chapter 1 we introduce the multi-scale experimental site of Settolo, an alluvial unconfined aquifer in north-eastern Italy that constitutes, as far as we know, the first multi-scale groundwater test site in our country. The installed instrumentation and the collected data are described, together with a preliminary data interpretation. In Chapter 2 we focus on groundwater modelling at the intermediate-scale. We calibrate a homogeneous 2D groundwater model to reproduce the Settolo field piezometric data and we explore the differences with a 3D model implemented with the same parameters and boundary conditions. We compare again the two models with spatial heterogeneity in the parameters. Because of the very similar performance of the 2D and 3D models we conclude that, in our case, the 2D model is suitable to describe the Settolo aquifer behavior at the intermediate scale; therefore, it can be effectively adopted for inverse modelling approaches and data assimilation. Chapter 3 introduces a novel global optimization algorithm implemented in a geostatistical framework to calibrate groundwater models. The proposed parallel algorithm is tested and validated under various conditions, with both homogeneous and heterogeneous parameter distributions, showing robustness and efficiency in solving the inverse problem, as well as scalability to high performance computing. Finally in Chapter 4 we focus on the geological facies-heterogeneity, not suitable to be described by classic geostatistical approaches like, for example, variogram based models. We approach the inverse problem with a strategy that combines multiple point geostatistics and sequential data assimilation with the ensemble Kalman filter, involving different kind of data, i.e., satellite images, electrical resistivity tomographies and time series of piezometric heads recorded in different locations. This approach is tested for the first time on a real-world case, and its advantages and limits are shown.
La caratterizzazione degli acquiferi naturali a scala intermedia è un problema di fondamentale importanza nell'idrologia sotterranea. Per intermedia si intende una scala compresa fra la scala locale, con dimensioni orizzontali del dominio comparabili con quella verticale, e la scala regionale, dove la dimensione verticale è di più ordini di grandezza inferiore a quelle orizzontali. Gli studi sulla scala intermedia sono estremamente importanti per una gestione corretta e sostenibile della risorsa idropotabile, per il controllo dell'inquinamento e per la protezione dal dissesto idrogeologico. A titolo di esempio, in Italia circa l'ottanta per cento dell'acqua potabile viene estratta dalle falde acquifere. La letteratura scientifica di settore è composta da numerosi studi che trattano il problema su scala regionale, con un minor numero di contributi a scala locale. In ogni caso l'ambito della scala intermedia risulta meno sviluppato: esso è caratterizzato da alcuni problemi aperti, quali, ad esempio, la scelta più adeguata dei modelli numerici da utilizzare e la definizione di metodi di stima dei parametri. Un grande limite, inoltre, è rappresentato dalla scarsità di siti sperimentali su cui testare e validare le teorie e i metodi sviluppati, aspetto che spesso rischia di rendere i risultati della ricerca difficilmente fruibili nelle pratiche applicazioni. Il lavoro presentato in questa tesi è diviso in quattro capitoli. (1) Gestione e caratterizzazione del campo prove multi-scala di Settolo (TV). È stata messa a punto la strumentazione del campo prove di Settolo-Valdobbiadene, in provincia di Treviso, per lo studio delle dinamiche multi scala di flusso e trasporto sotterraneo. Per quanto è noto, a dicembre 2013 esso è l'unico esempio in Italia di campo sperimentale su più scale (locale e intermedia). Un attento monitoraggio di livelli di falda, precipitazione, e condizioni al contorno unito ad analisi geotecniche, idrauliche, geofisiche, chimico-biologiche e topografiche, fornisce un notevole insieme di dati che consentono svariate applicazioni. (2) Confronto tra modelli 2D e 3D su scala intermedia. Un primo utilizzo dei dati del campo sperimentale è consistito nella comparazione dei risultati di due modelli numerici volta a determinare l'adeguatezza di una approssimazione shallow water all'ambito di analisi. Nel confronto sono stati presi in considerazione anche aspetti pratici quali la velocità di calcolo e la facilità di implementazione con specifico riferimento alle caratteristiche del sito in esame. (3) Messa a punto di un nuovo algoritmo di stima dei parametri e dell'incertezza. Un nuovo algoritmo di ottimizzazione globale, applicabile a svariati problemi di ottimizzazione, è stato formulato e validato. Tale metodo è stato applicato con successo nella stima dei parametri idraulici eterogenei dell'acquifero di Settolo, fornendo anche una valutazione spaziale dell'incertezza nella stima. (4) Applicazione a un caso pratico di un metodo di assimilazione dati e multiple point geostatistics. Un approccio di modellazione inversa che combina l'ensemble Kalman filter (EnKF) e le multiple point geostatistics (MPG), è stato applicato al campo sperimentale di Settolo-Valdobbiadene. Combinando dati diversi, quali immagini satellitari, tomografie geoelettriche del suolo, dati piezometrici di falda, precipitazioni e indagini geotecniche, si è cercato di ricostruire la distribuzione spaziale dei paleoalvei ghiaiosi, la cui posizione risulta fondamentale per poter definire con precisione le direzioni preferenziali di flusso e trasporto sotterraneo. Tale analisi, applicata per la prima volta un caso reale, ha messo in luce potenzialità e limiti dell'approccio utilizzato.

This thesis research consists of two separate studies. The first study presents the assessment and representation of the effects of soil macropores on the soil hydraulic properties in land surface models for more accurate simulations of soil moisture and surface hydrology. Hydraulic properties determine the soil water content and its transport in the soil. They are provided in most current climate models as empirical formulas by functions of the soil texture. Such is not realistic if the soil contains a substantial amount of macropores. A two-mode soil pore size distribution is incorporated into a land surface model and tested using an observational dataset at a tropical forest site with aggregated soils. The result showed that the existence of macropores greatly affects the estimation of hydraulic properties. Their influence can be included in land models by adding a second function to the pore-size distribution. A practical hydraulic scheme with macropore considerations was proposed given that the existing schemes are not applicable for large-scale simulations. The developed scheme was based on the physical attributes of the water in soil capillary pores and the statistics of several global soil databases. The preliminary test showed that it captures part of soil macropore hydraulic features without sacrificing the estimation accuracy of hydraulic properties of water in soil matrix. The second study presents the development of an integrated land/ecosystem model by combining the advanced features of a biophysically based land model, the Community Land Model, and an ecosystem biochemical model. The results from tests of the integrated model at four forest sites showed that the model reasonably captures the seasonal and interannual dynamics of leaf area index and leaf nitrogen control on carbon assimilation across different environments. With being coupled to an atmospheric general circulation model (AGCM), the integrated model showed a strong ability to simulate terrestrial ecosystem carbon fluxes together with heat and water fluxes. Its simulated land surface physical variables are reasonable in both geographic distribution and temporal variation with considering the interactive vegetation parameters.

The greenhouse industry is facing significant challenges such as the demand for more efficient use of energy and natural resources and prevention of detrimental environmental impacts. Reducing negative environmental impacts can be achieved by utilizing recycled and environmentally friendly products and by optimizing the use of water and root zone substrates. New and advanced root zone substrates are currently tested as substitute for natural soils in greenhouse agriculture. They can be inert non-organic materials such as rockwool and perlite. These are mined products from the earth, and are difficult to dispose after use. Natural substrates such as peat are being consumed faster than being regenerated. A new potential substrate that consists of recycled foamed glass aggregates is considered an alternative, as it is environmentally friendly, non-toxic and disposable. Experiments with foamed glass aggregates and with foamed glass aggregate/coconut coir mixtures indicated that the yield of greenhouse tomatoes was not statistically significant different (α=0.05) when compared to rockwool. To investigate the potential application of recycled glass as a root zone substrate, physical and hydraulic properties were measured. For comparison, the same measurements were completed for rockwool, coconut coir, perlite, and PET/PE fibers as well as for a mixture of coconut coir and recycled glass. The water characteristics (WC) determined for each substrate exhibited distinct air entry potentials, which provided information for irrigation scheduling, water storage and aeration for optimum plant growth conditions. Coconut coir and rockwool exhibited a unimodal shaped water retention curve, while foamed glass aggregates and perlite exhibited bimodal shaped curves. The obtained substrate properties were used as input paramaters for HYDRUS- 2D/3D model to simulate water mass balance and matric potential distributions within a typical growth container of foamed glass aggregates. The simulated matric potential and water content distributions were compared to tensiometer measurements of matric potential in the foamed glass aggregates. The simulations compared favorably with laboratory experiments measured under controlled environmental conditions.

Natural rubber has a good potential to be used as a material for the development of wave energy converters (WECs). Generally, rubber has the ability to withstand very large strains without permanent deformation or fracture and is not much affected by exposure to water. This makes it ideal for applications related to wave energy converter (WECs). However, there is a need to predict the efficiency of performance over the full lifetime of such an application given that WECs will represent large, expensive and novel products that must remain operational in an at-sea environment for 10-15 years. Pertaining to that criterion, fracture mechanics of rubber is an important aspect as well as strain-history and environmental effects. The objective of this study is to gain a fundamental understanding of several factors that contribute to service lifetime: the effect of ozone and oxidation, stress-strain behaviour including hysteresis, set, and cyclic stress relaxation, mechanical fatigue and the possible role of poorly dispersed filler agglomerates in nucleating failure. The work includes studies of the effect of protective coating layers and of naturally aged rubber artefacts using a mathematical model for diffusion limited oxidation. A literature review has been performed to address rubber science and associated technology, including, the durability of rubber. Experiments encompassing the effect of ozone, cyclic stress-strain behaviour and crack growth & fatigue of rubber were performed to interpret the relevant properties for the consideration of the development of wave energy converters. New parameters for characterizing macro dispersion in rubber are introduced in an attempt to seek a correlation with the life span of rubbers. All these observations and outcomes give an opportunity to enhance our understanding of the factors that determine long-term mechanical properties of rubber, to the general benefit of rubber science and technology.

The hydraulic conductivity distribution in a natural porous media is characterized by a great heterogeneity that makes its spatial assessment problematic and expensive. At the same time, a detailed knowledge of the hydraulic properties, as porosity, storativity, transmissivity and hydraulic conductivity K, is fundamental for the prediction of groundwater flow and solute transport in natural formations. Among the hydraulic properties, being the subsurface transport phenomena in natural formations mainly controlled by the Darcy's law, the proper definition of the K spatial distribution at different scales plays a fundamental role to evaluate the evolution of a contaminant plume, to define the well-catchment areas or to monitor a landfill site. To estimate aquifer hydraulic properties, inverse models have long been studied and, beyond the traditional hydraulic conductivity and head measurements, tracer test analyses have been widely adopted in the past and their use have increased in the recent years thanks to a great improvement of geophysical techniques. Among others, the Electrical Resistivity Tomography (ERT) allows to monitor a tracer test injection, providing time-lapse informations about the plume evolution with limited cost. Assuming that time-lapse spatially distributed data deduced from a tracer test are available, the present work investigates different approaches aimed to the estimation of the local K distribution. At this purpose, Kalman filter based data assimilation techniques are coupled with the Lagrangian transport model and applied in different synthetic contexts
La distribuzione di conducibilità idraulica in un mezzo poroso naturale è caratterizzata da grande eterogeneità, che rende la sua determinazione problematica e costosa. Allo stesso tempo, una approfondita conoscenza delle proprietà idrauliche, quali la porosità, l'immagazzinamento specifico e la conducibilità idraulica K, è di fondamentale importanza per poter predire e analizzare il flusso sotterraneo e il trasporto di soluti in formazioni naturali. Poichè i fenomeni di trasporto sotterraneo che si realizzano negli acquiferi sono principalmente controllati dalla legge di Darcy, tra le diverse proprietà idrauliche sopraccitate, un'opportuna definizione della distribuzione spaziale di K gioca un ruolo fondamentale nella predizione del plume di inquinanti, e quindi assume particolare rilevanza in molte attività di pratico interesse, quali la definizione delle aree di salvaguardia dei pozzi o il monitoraggio di discariche. Le proprietà idrauliche degli acquiferi sono di norma stimate con l'ausilio di modelli inversi utilizzando, oltre le tradizionali misure di conducibilità idraulica e piezometria, quelle derivanti da analisi di iniezioni controllate (test con traccianti o tracer test nella comune dizione anglosassone). I test con traccianti sono stati in diverse occasioni adottati nel passato ma il loro uso è aumentato negli anni recenti grazie agli sviluppi delle tecniche geofisiche che semplificano il monitoraggio delle prove in situ. Fra queste, la Tomografia Elettrica Resistiva (ERT) sembra essere la più appropriata per misurare le quantità di interesse nel caso di iniezioni di traccianti, essendo possibile acquisire un grande numero di informazioni sull'evoluzione spazio-temporale dell'evoluzione del plume, a costi relativamente limitati. Partendo dal presupposto che siano disponibili misure derivanti da una iniezione controllata in pozzo, il presente lavoro suggerisce alcuni approcci che, sulla base dei dati deducibili dalle misure ERT, permettono di stimare la distribuzione spaziale di K e verifica la loro effettiva capacità predittiva. Tali modelli risultano dall'accoppiamento di tecniche basate sul filtro di Kalman con modelli di trasporto Lagrangiano: l'applicazione ad una estesa serie di casi sintetici ha permesso inoltre di ottenere utili indicazioni in relazione a vantaggi e svantaggi di ciascuna delle metodologie proposte

Landfills are considered to be one of the major sources of anthropogenic methane (CH4) emissions in the environment. A landfill biocover system optimizes environmental conditions for biotic CH4 consumption that controls the fugitive and residual emissions from landfills. A compost material has more oxidation potential in comparison to any other material due to its high porosity, organic content, free flux for gases and water holding capacity. Thermal, hydraulic, bio – chemical and mechanical (THMCB) properties are important factors that can significantly affect the performance of biocover material with regards to CH4 oxidation potential as well as structural stability. Technical data on the thermal, hydraulic and mechanical (THM) properties of compost based biocover materials are quite limited. Hence, a detailed experimental program has been carried out at the University of Ottawa to study the THM properties and behaviour of compost biocover material by conducting experimental tests on small compost samples as well as by performing column experiments. The test results indicate that lower water content (dry of optimum for compaction curve) shows more free air space (FAS) in comparison to higher water content. The compost has almost the same shear strength for various initial water contents and dry unit weights; however, it settles and swells more at higher water content than lower water content per mechanical test results. The thermal and hydraulic properties of compost are a function of the compaction degree in addition to various other parameters. It is also found that the THM properties of compost are strongly coupled and the degree of saturation greatly affects the FAS.

An understanding of the distribution and ranges of hydraulic and physical properties of the subsurface sediments in the Upper San Pedro Subwatershed in Southwestern Arizona is needed to estimate infiltration and recharge rates to the aquifer system. The objectives of this thesis are to compare measured saturated hydraulic conductivity values to standard references and to test available predictive models of soil hydraulic properties based on particle size distributions against hydraulic properties measured directly on undisturbed cores. Hydraulic and physical properties compared well to standard references. The predictive models compared well with sand type sediments, but did not compare well with those cores with large percentages of clay and silt. A conclusion is that predictive models may not produce adequate results to estimate infiltration and recharge rates to an aquifer system if the subsurface sediments have large percentages of clay and/or silt. Furthermore, exclusion of large percentages of gravel may produce inaccurate results for physical and hydraulic properties.