Extension of Automated Parameter Determination framework to cope with fine-grained soils

Abstract

The Automated Parameter Determination project aims to provide advanced geotechnical models parameters from in-situ tests in a transparent and flexible process. The framework was initially developed for coarse-grained soils, and it was needed to be expanded to all types of common soils. This report presents the expansion of the APD database to deal with fine-grained soils, claylike soils specifically. The APD variability assessment framework is customised to deal with log-transformed correlations’ uncertainty. Moreover, it is found a large dependency on Atterberg limits for claylike soils parametrisation. Only one set of correlations from CPT database is found in literature to obtain these limits, for which a new set is developed based on critical state soil mechanics and the assumption that the CPT friction sleeve is similar to the remoulded undrained shear strength. The proposed correlation is validated with a published database, showing acceptable results with similar variability when compared to the existing equation. A first validation of the complete model parameters for fine-grained soils using Plaxis Hardening Soil with small strain stiffness model is achieved. The Plaxis Soil Test facility is used and the results are compared with triaxial and oedometer tests, showing good results in compressibility characterisation and low estimation of friction angle, possibly attributed to organic and silt content. The friction angle characterisation is discussed, and it is concluded that a better estimation for fine-grained soils is needed to be studied. Further studies on soils in between claylike and sandlike behaviour is needed, as well for organics.