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Stone columns - importance of arch effect
Vanko, Peter ; Zdražil, Karel (referee) ; Miča, Lumír (advisor)
The aim of the the thesis is to study the development of arch effect depending on the change of the various parameters such as grid of columns, height of embankments, material of embankment fill and material of columns. The first phase of work summarizes theoretical knowledges of stone columns and arch effect. The next phase deals with analysis of the effect of arch using numerical modeling. In the next part of the second phase circular tank based on stone columns will be modeled, where deformations and stress on columns will be monitored in changing constitutive model and applying substitute characteristics. Obtained results will be evaluated in conclusion.
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Geothermal energy - influence of the borehole geometry
Leiter, Augustin ; Frankovská,, Jana (referee) ; Hrubešová,, Eva (referee) ; Miča, Lumír (advisor)
Geothermal energy is one of the oldest forms of energy on our planet. Its use by humanity dates back to the beginning of the ages. The forms of this energy gradually changed from the direct heat of the hot springs, through the heating of the buildings and the baths to the later use of superheated steam for industrial use. Nowadays, there is a large share of the use of large number of ground geothermal boreholes with heat exchangers drilled in the matrix. The geometric arrangement of such system has a considerable impact on its operation. Specific examples show that, unlike the design, actual boreholes in such system can often be drilled non vertically or even curved. These imperfections then usually deteriorate the thermal properties of the system. This thesis demonstrates the influence analysis of the borehole geometry distortion on the system thermal properties, it also informs about the development of a special measuring device designed to obtain information about the actual geometric shape of the investigated borehole and about the development of software for in situ rapid borehole system properties evaluation. The theoretical part of thesis contains the derivation of a simplified numerical model of heat conduction in the vicinity of the borehole system. Its results serve to compare the different borehole variants and the inaccuracy of borehole shaping. Using the simulations, the influence of inaccuracies in the borehole system on its thermal properties is demonstrated in several model configurations. This effect does not occur in a single borehole, but it is significantly visible in organized geothermal borehole systems. It may deteriorate system properties, but under certain circumstances its properties may improve. Verification of the results of these simulations was performed by the FEFLOW simulation software. In the practical part the development of a special instrument for measuring the shape of a geothermal energy borehole is documented. ....
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The study the behavior of the reinforced soil block under the concentrated load
Prechtlová, Kateřina ; Kliš, Lumír (referee) ; Miča, Lumír (advisor)
This thesis deals with numerical 3D modeling of reinforced earth block under concentrated wheel load. This is a parametric study, which varies entering face and load position and even his own task. And either by simplification of the CSN 73 0037 or directly. At the beginning briefly describes the construction of reinforced soil in terms of history, application, construction, and properties of materials from which the structure is formed. Attention is also paid to static action and methods of spreading of a concentrated load to earth block. structural design using analytical methods is also part of the thesis
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Design of excavation for reconstruction of shopping centre
Červenka, Jan ; Miča, Lumír (referee) ; Chalmovský, Juraj (advisor)
The thesis is divided into three parts. In the first one it deals with the design and the assessment of the once-anchored soldier pile wall, which provides an excavation for the reconstruction of the shopping centre Prior in Zlín. The retaining structure is designed according to the limit state method, using the GEO5 software and the Excel spreadsheet editor. In the second part, the thesis deals with the price comparison of the classic version of the soldier pile wall with soldier pile, IPN profiles, with over one-pole anchorage with the help of the buckle, with the variant with larger spread, where the soldier pile from the pair of UPN profiles are adapted for anchoring. The third part solves the problem of the distribution of a lateral ground pressures along the length of the soldier pile wall. For comparison with the empirical methods of design of lagging, the results of normal pressure from the mathematical model, solved by the numerical analysis, the finite element method, were used in the Plaxis 3D program. Hardening soil model was used as the material model.
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Design of foundation pit in metro construction in the section Dejvická - Motol
Krško, Matúš ; Kliš, Lumír (referee) ; Miča, Lumír (advisor)
Diploma thesis deals with design and assessment of bracing the excavation during the construction of subway in the route Dejvická – Motol. The introduction presents possible methods of bracing. The next part is design and assessment of the chosen option, which ensure this construction. It consists of considering of engineering-geological conditions, static design, technological process of building and construction plans.
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Design of excavation in the Brno city centre
Kováč, Vladimír ; Miča, Lumír (referee) ; Chalmovský, Juraj (advisor)
The work deals with the problem of the ultimate and serviceability limit state of a once-anchored retaining structure of an excavation on Krenova street in Brno. The calculation of the ultimate limit state is solved manually and provides an input into the serviceability limit state, which is solved by means of a numerical analysis using a finite element method. To calculate the serviceability limit state, these constitutive models: Mohr-Columb, Hardening soil and Hardening soil small strain model are used.
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Comparison of two alternatives of deep excavation design
Krejzar, Vojtěch ; Miča, Lumír (referee) ; Chalmovský, Juraj (advisor)
The thesis focuses on numerical modeling of a 30 m deep excavation using the finite element method (FEM). The excavation is situated in Luzern, Switzerland. The subsoil is formed by inclined sandstone or siltstone layers; one of them tends to form a dangerous slip surface. The bachelor’s thesis compares 2 alternatives: Alternative A represents a combination of an anchored pile wall and sprayed concrete in the lower part of the excavation, Alternative B represents a full height anchored pile wall. The thesis comprises of the description of modeling, determination of material parameters and structural members’ inputs, defines calculation phases and predicts the structure deformations. The mathematical model is created using PLAXIS 2D software.
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Determination of input parameters of advanced soil constitutive models using optimization methods
Koudela, Pavel ; Miča, Lumír (referee) ; Chalmovský, Juraj (advisor)
Choice of the constitutive model and determination of input parameters are necessary for a successful application of numerical methods in geotechnical engineering. Higher complexity of modern constitutive models results in an increase of the number of input parameters and time requirements for their calibration. Optimization methods are a possible solution for this problem. An application in which metaheuristic optimization method Particle swarm optimization (PSO) is involved is presented in this thesis. Critical review and testing of various PSO alternatives was performed in the first part of this thesis. The most efective PSO alternatives were chosen. In the second part connection between PSO algorithm and finite element solver was prepared. Automatization of determination of constitutive models input parameters was performed on three boundary value problems: laboratory test (oedometer), in-situ test (pressuremeter) and geotechical construction (retaining wall). Three types of constitutive models are used. Linear elastic-perfectly plastic Mohr-Coulomb model, elastoplastic non-linear Hardening soil model and Hardening soil - small strain model.
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Design of sheeting on a excavated section of tunnel on a high-speed line Brno-Přerov
Umlauf, Jiří ; Boštík, Jiří (referee) ; Miča, Lumír (advisor)
In first part of the thesis are proposed four variants of retaining structures for deep excavation of cut-and-cover tunnel part. It is nailed slope, pile wall, nailed slope in combination with pile wall and soldier pile wall. For those structures is in following part carried out an economic analysis and the most cost effective variant is chosen. Chosen structure is further analyzed in next part. This analysis is carried out with finite element method in software PLAXIS. As a material model is chosen Hardening Soil model and input parameters were determined by empiric formulas from literature. Behavior of neogene clays, in which is the structure designed, is considered as undrained, by type Undrained A. In the last part of the thesis is described technological procedure of construction this retaining structure.
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