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Application of probabilistic methods in geomechanics
Suchomel, Radek ; Mašín, David (advisor) ; Šejnoha, Jiří (referee) ; Pruška, Jan (referee)
Three probabilistic methods of different complexity for slope stability calculations are in this work evaluated with respect to a well-documented case study of slope failure in Lodalen, Norway. A finite element method considering spatial random fields of uncorrelated parameters cohesion and friction angle is taken as a reference for comparison with two simpler methods based on Taylor series expansion, known as first-order-second-moment methods. It is shown that the FOSM method enhanced by a reduction of variance of input parameters due to spatial averaging along the potential failure surface leads to a significant improvement in predictions. This method is computationally inexpensive and can be used in combination with any existing finite element code, it is thus a useful approximate probabilistic method for geotechnical practice. Several limitations of the extended method for calculating probability of a slope failure are identified. An advanced hypoplastic constitutive model is used in probabilistic analyses of a typical geotech- nical problem, strip footing. The model, including horizontal and vertical correlation lengths, was calibrated using a set of experimental data on sand from horizontally stratified deposit. Some parameters followed normal, whereas other followed lognormal distributions....
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Comprehensive study of the sandstone rock forms deterioration (Case study: Pravčická brána Arch, Bohemian Switzerland National Park)
Vařilová, Zuzana ; Přikryl, Richard (advisor) ; Vilímek, Vít (referee) ; Mikuláš, Radek (referee)
This PhD thesis contains the results of comprehensive research into the Pravčická brána Arch and surrounding sandstone massifs with focus on gaining more knowledge about natural dynamics and evolution of this rock formation, its current level of stability and the weathering processes it displays. Non-destructive methods were used for this comprehensive study; these ranged from detailed field documentation to monitoring temperature regime of the rock and included application of a geophysical survey and control monitoring of the course of arch body deformation. Laboratory testing was carried out for strength parameters and salt efflorescences together with weathered sandstones were analysed for chemical compounds. Main operating factors were monitored simultaneously, which particularly involved changes in external temperature, degree of sunlight and chemical composition of rainfall. Conventional as well as entirely new assessment procedures were used in synthesis and interpretation of the data collected, including knowledge of nonlinear dynamics of complex systems. The survey was designed to fully respect the protective conditions of the site, to make follow-up activities possible in future and to monitor any possible negative changes in the rock massif. The main results incorporate description of...
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Application of probabilistic methods in geomechanics
Suchomel, Radek ; Mašín, David (advisor) ; Šejnoha, Jiří (referee) ; Pruška, Jan (referee)
Three probabilistic methods of different complexity for slope stability calculations are in this work evaluated with respect to a well-documented case study of slope failure in Lodalen, Norway. A finite element method considering spatial random fields of uncorrelated parameters cohesion and friction angle is taken as a reference for comparison with two simpler methods based on Taylor series expansion, known as first-order-second-moment methods. It is shown that the FOSM method enhanced by a reduction of variance of input parameters due to spatial averaging along the potential failure surface leads to a significant improvement in predictions. This method is computationally inexpensive and can be used in combination with any existing finite element code, it is thus a useful approximate probabilistic method for geotechnical practice. Several limitations of the extended method for calculating probability of a slope failure are identified. An advanced hypoplastic constitutive model is used in probabilistic analyses of a typical geotech- nical problem, strip footing. The model, including horizontal and vertical correlation lengths, was calibrated using a set of experimental data on sand from horizontally stratified deposit. Some parameters followed normal, whereas other followed lognormal distributions....
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