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Evaluation of loading test of jet-grouted piles
Čechová, Simona ; Račanský, Václav (referee) ; Chalmovský, Juraj (advisor)
The master thesis consists of a theoretical part and a practical part. In the theoretical part jet-grouting technology is described briefly. Mechanical properties of jet-grouted piles were characterized. Various estimation methods of ultimate pile bearing capacity are described in this thesis – analytical calculation of ultimate bearing capacity for bored piles and estimation of ultimate pile bearing capacity by analysis of load-displacement curve defined by CHIN (1970; 1972). Load transfer method for piles and hyperbolic load-transfer curve are introduced. As a part of the load-trasfer method analysis, a method of estimating ultimate pile shaft friction called beta method is defined. In the practical part were evaluated several static load tests of jet-grouted piles and were constructed their load-displacemnt curves. Then reverse analysis of the results from static load tests was performed using load-transfer method. Then ultimate pile bearing capacity was estimated using analytical calculation of pile bearing capacity for bored piles and using analysis of load-displacement curve with method by CHIN (1970; 1972). By evaluation of load transfer method and beta method ultimate shaft resistence for each pile was estimated. Results and load-displacement curves were compared.
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Evaluation of selected load tests of ductile piles instrumented with distributed fibre optic sensors
Genzer, Christian ; Račanský, Václav (referee) ; Chalmovský, Juraj (advisor)
Despite the fact that the use of driven ductile piles is not as widespread in the Czech Republic as in surrounding countries, this method provides a fast and reliable solution for foundation structures. To verify and optimise the design, in-situ load tests are often carried out on a realistic scale. As a standard, string or resistance strain gauges are used to measure the resulting deformations. Although their use is cheap and relatively simple, the measured results do not provide a complex view of the behaviour of the structure over its entire length and with sufficient accuracy. Therefore, in recent years, the application of fiber optic-based measurement systems has been increasing. The goal of this bachelor thesis was to evaluate several load tests of driven ductile piles fitted with fibre optic sensor systems, considering a number of factors that negatively affect the measurement results. Examples of these include pile bending, measuring oscillations due to the technology of execution and the method of measurement, or the development of tension cracks in the grouting. For each load test, the site geology and test pile parameters were specified first. Afterwards, the technology of the performed load test was described and the results of standard monitoring were presented. Based on the measuring from distributed fibre optic sensors, the relative strain and axial force curves were constructed, from which the ultimate skin friction values were determined. These values were correlated with the driving times in each pile section and based on this relation the K_SHAFT coefficients were set. At the end of the thesis is presented a summary of the collected data and their comparison between each other.
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Prediction of load-displacement behaviour of large diameter piles using the finite element method
Dvořák, Tomáš ; Miča, Lumír (referee) ; Chalmovský, Juraj (advisor)
The master thesis deals with the inverse analysis of instrumented load tests of bored piles in cohesionless and cohesive soils. Evaluations of the detailed monitoring are compared with the results of inverse analyses. Inverse analyses are preformed using the finite element method with an advanced material model considering the higher stiffness within very small strains in PLAXIS and alternatively using the load-transfer method in PMpLTO. The difference of pile-soil interaction in different soil types is discussed and the difference in the process of shaft friction mobilization is also evaluated. In cohesionless soils values of shaft friction are many times higher due to the increment of radial stress which is caused by effect of constraint dilatancy in shear zone at pile-soil interface.
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Evaluation of loading test of jet-grouted piles
Čechová, Simona ; Račanský, Václav (referee) ; Chalmovský, Juraj (advisor)
The master thesis consists of a theoretical part and a practical part. In the theoretical part jet-grouting technology is described briefly. Mechanical properties of jet-grouted piles were characterized. Various estimation methods of ultimate pile bearing capacity are described in this thesis – analytical calculation of ultimate bearing capacity for bored piles and estimation of ultimate pile bearing capacity by analysis of load-displacement curve defined by CHIN (1970; 1972). Load transfer method for piles and hyperbolic load-transfer curve are introduced. As a part of the load-trasfer method analysis, a method of estimating ultimate pile shaft friction called beta method is defined. In the practical part were evaluated several static load tests of jet-grouted piles and were constructed their load-displacemnt curves. Then reverse analysis of the results from static load tests was performed using load-transfer method. Then ultimate pile bearing capacity was estimated using analytical calculation of pile bearing capacity for bored piles and using analysis of load-displacement curve with method by CHIN (1970; 1972). By evaluation of load transfer method and beta method ultimate shaft resistence for each pile was estimated. Results and load-displacement curves were compared.
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