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Hydromechanic characteristics of clay suspensions
Sedláčková, Markéta ; Mls, Jiří (advisor) ; Císlerová, Milena (referee) ; Šembera, Jan (referee)
A mathematical model of two-phase systems, such as clay suspensions, consists of a set of partial differential equations which reflect both the general laws of mechanics and the relations connecting the involved characteristics of the particular system under consideration. The latter equations are known as constitutive relations. The aim of this study was to find the constitutive relations for kaolin suspensions that are necessary when solving forward problems of fine sludge thickening processes. The task was to design and carry out experimental research of the given suspension and to find a convenient method of utilizing the results for the sake of getting the sought relationships. It follows from the applied mathematical theory of two-phase systems that the sought relationships are hydraulic conductivity of the suspension as a function of the solid-phase concentration and the dependence of the solid-phase concentration on the solid-phase stress. The first part of this study describes the experimental research. Since both the characteristics are difficult to measure, it was necessary to analyze the suspension's characteristics and their measurability. Subsequently, the process of the suspension preparation and the method of laboratory measurements were determined. The following sections present...
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Comparison of hydraulic characteristics of cavernous weathering rocks forming tafoni and honeycombs
Studencová, Alžběta ; Bruthans, Jiří (advisor) ; Sněhota, Michal (referee)
Forms of cavernous weathering - tafoni and honeycombs - belong to long-term investigated and discussed phenomena in geology. The reason for the difference in size between few centimetres- long honeycombs and the several-metres-long tafoni has not been yet studied. In my master thesis I compared the hydraulic properties of rocks with developed honeycombs and tafoni. The research consists of field measurements (measurement of suction pressures and capillary water absorption using Karsten tube) and laboratory measurements on tafoni and honeycomb samples (retention curve measurement, capillary water absorption, water vapour diffusion rate and saturated hydraulic conductivity). I have been studing honeycombs from various sites in the Bohemian Cretaceous Basin and tafoni from three different sites: Carbon Arkoses near Kralupy nad Vltavou, Cambrian Sandstone in Petra (Jordan) and Tunnel Spring Tuff in Crystal Peak (Utah). The measurements showed that values of suction pressure are far higher inside tafoni than inside honeycombs. This observation corresponds to different retention curves of studied rocks: steeper retention curve for honeycomb's quartz sandstone than for fine-grained arkosic sandstones to arkoses with tafoni. In the other part of my research I have compared the properties of hydrophobic...
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Influence of CaO on structure and permeability of clayey soil
Pastyriková, Zdeňka ; Boháč, Jan (advisor) ; Frankovská, Jana (referee) ; Sněhota, Michal (referee)
The aim of this study was to determine the effect of quicklime (1 - 8% CaO) and maturation time (1 - 540 days) on the structure of clayey soil compacted at optimum moisture content by Proctor standard energy and whether expected change in structure affects the long - term permeability. The change of pore space of compacted loess with 1-8% lime (CaO) was studied by mercury porosimetry (MIP) for a long period of maturation (from 1 to 540 days). Development of pozzolanic reactions were monitored by measuring the pH. The development of new mineral phases (calcium silicate hydrates, calcium aluminate hydrates and calcium aluminate carbonate hydrate) in the treated soil was investigated by using X-Ray diffraction. The MIP indicated that 2% of CaO were sufficient for long term pozzolanic reaction. The threshold value is below the initial consumption of lime determined from the pH measurements (Eades and Grim, 1966). The alteration of the voids of the lime treated soil is noticeable, but the pH value can not drop below 11.7. At 4% of CaO, at 8% of CaO respectively, the macroporosity kept decreasing due to increasing mesoporosity for 360 curing days, for 540 curing days respectively, due to the new mineral phases. At 2% of CaO, the decrease of the macroporosity stops after 120 days. Below 2% of lime, the...
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Hydraulic conductivity of sandstone samples
Kobrlová, Alžběta ; Bruthans, Jiří (advisor) ; Ondovčin, Tomáš (referee)
Saturated hydraulic conductivity (k) describing the ability of the porous media to allow flow is defined by Darcy's low. Beside pore space properties it depends on the properties of liquid; therefore it is conventionally determined for water at 15 řC. Values of hydraulic conductivity vary between m/s and m/s for sands and sandstones and rises with increasing grain size and porosity. Hydraulic conductivity can be estimated by empirical formulas or measured by laboratory and field methods. Laboratory determination includes the constant head and the falling head permeameter tests. The constant head permeameter test is suitable for material with values of hydraulic conductivity ranging between m/s and m/s; the falling head test for values between m/s and m/s. Unsaturated hydraulic conductivity is a function of moisture (and pressure head). Retention curve describing the dependence of moisture on pressure head is the basic characteristic of each material. The unsaturated hydraulic conductivity can be calculated from the parameters of retention curve and the value of the saturated hydraulic conductivity using Van Genuchten - Mualem formula (1980). Fine grain rocks with small pores have higher values of hydraulic conductivity than coarse grain rocks in condition of significantly negative values of...
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Comparement of results from infiltration tests
Blahut, Dominik ; Mazáč, Petr (referee) ; Duchan, David (advisor)
The aim of this thesis is to compare the results of water infiltration from field tests, from laboratories and from numerical modeling at two selected locations. The first objective is the search procedure and the description of both sites and its adjacent areas. Further work continues with infiltration field tests using ring infiltrometer, at first theoretically for each method, and then practically with own personal measurements in the field. Further from the collected soil samples the measurements are performed in the laboratory, first in the permeameter, and followed by the grain size distribution test, from which the hydraulic conductivity is derived by using empirical formulas. At last the numerical modeling is used and all the results are compared. In the final phase of thesis the recommendations are given for infiltration at various locations and comparsion of the infiltration methods.
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Assessment of empirical formulae for determining hydraulic conductivity
Barenčík, Ladislav ; Zachoval, Zbyněk (referee) ; Říha, Jaromír (advisor)
The main purpose of this diploma thesis is to check up and compare empirical formulae (Hazen, Slichter, Terzaghi, Beyer, Zauerbrej, Krüger, Kozeny, Zunker, Zamarin, USBR, Pavčič) for determining hydraulic conductivity, which are mostly publicated in different and dimensionally inhomogenous forms. The importance of an accurate determination of hydraulic conductivity and the derivation of a general formula for determining hydraulic conductivity are listed in the first part of this diploma thesis. Assessment methodology and empirical formulae in dimensional homogenous form are described in the following part. Evaluating and comparing of empirical formulae is mentioned in the last part. According to the results of this diploma thesis, the best empirical formula for determinig and estimating hydraulic conductivity is Hazen formula. Formula with the widest range of validity is Slichter formula.
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Determination of soil hydraulic characteristics in the selected location
Stoklásková, Adéla ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
This thesis deals with direct and indirect determination of soil hydraulic characteristics (retention curve and hydraulic conductivity) in the locality of Bohaté Málkovice. For laboratory determination of soil moisture retention curve is used sand tank and pressure relief device. For the indirect determination of soil hydraulic characteristics is used computer software Rosetta, which includes 5 models of pedotransfer functions. For estimatiton of retention curves are applied previously derived pedotransfer function (continuous parametric PTF and point PTF).
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Hydraulic conductivity under various recultivated growth
CEJPEK, Jiří
Velka podkrusnohorska spoil heap in the Sokolovsko region is the largest heap in the Czech republic, which was created by transfering millions of tons of soil from opencast mining of brown coal. According to a large measuring (large land surveying) of physical and chemical properties on the reclaimed and unreclaimed heap soil were found many hydrological properties. Hydraulic conductivity was measured by Guelph permeameter, moisture was measured by Dielectrical indicator of moisture and last but not least soil carbonates Ca was measured by Janek`s carbonmeter. Water mode and percantual representation of carbonates is markedly influenced by the technology of sending and by the age of heaps of both types, differencies between bottom parts and top parts on unreclaimed soil are conclusive due to crevasses on the top parts. The other factor is the presence of reclaimed vegetation, which have an important role in the pedogenic process.
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