Influence of uncertain soil models on the construction and design of geotechnical structures

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In this research project within the SPP 1886 it is supposed to investigate the variation of soil state variables, stress state and void ratio, and its influence on the result of cone penetration tests (CPTs) and beyond on the design of geotechnical structures. With the help of available CPT data from a geotechnically well explored test site in Hamburg an inverse parameter determination with numericaloptimization will be performed, allowing to deduce the vertical stress and void ratio distribution by numerical simulation of the CPTs. With the soil models obtained in this way further numerical simulations, e. g. simulations of full displacement piles at the test site, which are also covered by measured data, will be performed. The numerical and measured results will be used to investigate and develop correlations between CPT tip resistance and soil state variables. Furthermore, the correlation of machine parameters, obtained during pile installation, with soil properties and with estimated pile bearing capacity will be evaluated. All in all, the influence of data variance and uncertainty on the numerical results and on the design will be investigated. In a proposed second research period the initially assumed axisymmetric investigations are supposed to be expanded to a full three-dimensional numerical model of the test site. In this model a random distribution of the soil state variables, stress state and void ratio, will be determined from the available grid of CPT soundings. For this purpose, a fractal distribution of state variables is assumed. With the help of the three-dimensional models further numerical investigations on the influence of variance of soil state variables on the numerical design of geotechnical structures will be performed.