Numerical analyses of field vane tests on soft clays

This paper focuses on the use of field vane, a popular instrument for determining the undrained shear strength (su) of soft clays. In this regard, suitable corrections must be applied in order to adequately interpret the recorded measurements. Here the role played by some relevant factors (i.e., anisotropy and strain-rate effects) in influencing su values is investigated on the basis of FEM numerical analyses carried out via the adoption of PLAXIS-3D software. The results of the numerical analyses generally fit with information provided by the scientific literature using independent measurements. Moreover, they highlight a relevant effect of anisotropy for low values of the plasticity index of investigated clayey soils. On the contrary, for high values of the plasticity index, anisotropy plays a marginal role while strain rate effects prevail. All these considerations suggest the field vane tests most reliable for clayey soils with high plasticity index, although a correction is needed in order to limit strain rate effects.