Poroelastic Modeling of Piezocone Tests Using Poroelastic Cavity Expansion Analysis

Resumo

The CPTu (Cone Penetration Test with pore pressure measurements) is a field test widely used to
obtain stratigraphic characterization and geotechnical properties of a subsoil profile. In general, the speed used
for driving the cone is standardized at 20 mm/s. In this way, predominantly sandy soils tend to show drained
behavior, in such manner the analysis is based on effective tensions; and predominantly clayey soils tend to
show undrained behavior, thus the analyze is based on total stresses. In this sense, classical methods of
interpretation are set to define with an accepted reliability behavior of typical sands or clays. However, for
mixtures or silty soils, drainage may be partial. In this condition, the pore pressure around the cone is altered
introducing errors in the interpretation. The present work aims to present a model capable to identify the
drainage behavior of soils submitted to CPTu with intermediate permeability characteristics (silty soils). To
evaluate the drainage behavior during the execution of the test, simplified semi-analytical models of cylindrical
cavity expansion were developed, based on the theories of poroelasticity presented by Biot [1]. Preliminary
results indicate that the model has the capacity to evaluate the typical drainage behavior of the soil submitted to
CPT.