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Thermo-hydro-mechanical coupling in slope stability: advanced experiments and multiscale modelling
Loche, Marco ; Scaringi, Gianvito (advisor) ; Comegna, Luca (referee) ; Görüm, Tolga (referee)
The complexity of the thermo-hydro-mechanical processes in expansive clays is such that coupled models are needed to explain their behaviour under variable hydraulic, mechanic, and thermal conditions. The effects of temperature changes on the behaviour of bentonite are being studied, in particular, with respect to their role in the chemical and hydraulic insulation of radioactive waste. Results demonstrate that thermal effects can be significant. These effects can also occur owing to different processes, such as seasonal thermal variations in the shallow (possibly clay-rich) soil layers along mountain slopes. Very limited research in this field has shown that some landslides might be activated by thermal excursions. In the proposed project, experiments and modelling at various scales have been performed to better account for thermo-hydro-mechanical coupling and for the control of temperature on the shear strength, and hence on the stability of slopes. An extensive variety of geotechnical parameters are subjected to changes under thermal action. For instance, we need to mention the shear strength. To develop a more complete framework to account for temperature in slope stability analysis, a multi-scale approach has been defined to improve our understanding on how soil behaves under thermal changes....
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Development and validation of a hypoplastic model for soft clays incorporating rate effects and strength anisotropy
Jerman, Jan ; Mašín, David (advisor) ; Blahůt, Jan (referee) ; Hrubešová, Eva (referee)
The thesis presents modelling framework for soft clays. Soft clays typically occur in marine environment, coastal areas and along rivers, soft clay deposits are also associated with the periglacial conditions. Soft clay seabeds are also prevalent in locations used as foundations of various energy sources (renewable and hydrocarbon). Growing world population increased demand for land, and this, consequently, leads to seaward land reclamation for urban development in coastal areas. Thus, construction on soft soil deposits has become increasingly important as soft clays occur in locations of construction projects for city infrastructure. The stress-strain behaviour of soils, especially clayey soils, is well-known to be rate- dependent. This fact is relevant for specific engineering projects, where the long-term performance of constructions is of interest. This is particularly important for soft clays as the very high degree of compressibility in primary compression and during creep makes rate-dependent soil behaviour an important factor for geotechnical problems. Moreover, the slow slope movements of slow-moving landslides and creeping slopes are controlled mostly by shear creep properties of the shear-zone soil and the effective stress state. Thus, for the case of creeping landslide modelling, a...
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Development of calibration methods for hypoplastic models
Šula, Igor ; Mašín, David (advisor) ; Janda, Tomáš (referee)
The calibration application named ExCalibre was developed at Technical University in Prague, Faculty of Civil Engineering. This application can automatically process experimental data and create set of parameters of hypoplastic models which are designed for saturated clays or sands. The aim of this master thesis was to support development of application for calibration with testing it on real experimental data sets. Automatic calibration of these data sets was compared with calibration by hand for identical data. The development of the application and main phase of testing took place in two stages, where the main calibration errors of calibration application were identified. After the final testing of application where the minor bugs and errors were overcome a user-friendly web application (soilmodel.com/excalibre/) was introduced. This final testing has gone beyond this thesis. The results from the main phases of testing are discussed in this thesis as well as the description of database of fine-grained and coarse-grained samples which were used to testing of application. Knowing the calibration of the model is crucial for its using, you can find description of the used constitutive models in this thesis, which are used in the calibration application, as well as a description of procedure for...
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Contributions to the experimental investigation and numerical description of soil cyclic behavior
Duque Felfle, Jose Alejandro ; Mašín, David (advisor) ; Herle, Ivo (referee) ; Wichtmann, Torsten (referee)
A wide range of geotechnical structures are subjected to episodes of cyclic loading. Among them, we can for example mention onshore and offshore foundations subjected to environmental loadings, pavements subjected to traffic loading, filling-emptying cycles on silos and water tanks, among many others. In order to develop constitutive models or numerical tools that accurately reproduce the soil behavior on the aforementioned geotechnical problems, a deep understanding on how soil behaves under cyclic loading is necessary. This behavior is, however, not trivial since non-linearity, small strain stiffness, stiffness degradation, cyclic hysteresis and recent stress history play a significant role. This dissertation presents some contributions to the experimental evidence and numerical description of soil cyclic behavior. It begins with comprehensive experimental databases on Malaysian kaolin and Zbraslav sand. In each database, several monotonic and cyclic tests were performed and analyzed considering a wide range of initial conditions and loading characteristics. In particular, the influence of the deviatoric stress amplitude, soil plasticity, initial stress ratio, drained cyclic preloading and sequence of packages of cycles with different deviatoric stress amplitudes was investigated on Malaysian...
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Development of calibration methods for hypoplastic models
Šula, Igor ; Mašín, David (advisor) ; Janda, Tomáš (referee)
The calibration application named ExCalibre was developed at Technical University in Prague, Faculty of Civil Engineering. This application can automatically process experimental data and create set of parameters of hypoplastic models which are designed for saturated clays or sands. The aim of this master thesis was to support development of application for calibration with testing it on real experimental data sets. Automatic calibration of these data sets was compared with calibration by hand for identical data. The development of the application and main phase of testing took place in two stages, where the main calibration errors of calibration application were identified. After the final testing of application where the minor bugs and errors were overcome a user-friendly web application (soilmodel.com/excalibre/) was introduced. This final testing has gone beyond this thesis. The results from the main phases of testing are discussed in this thesis as well as the description of database of fine-grained and coarse-grained samples which were used to testing of application. Knowing the calibration of the model is crucial for its using, you can find description of the used constitutive models in this thesis, which are used in the calibration application, as well as a description of procedure for...
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