On the use of multi-directional piezoelectric transducers in triaxial testing

Based on the well-known and largely consolidated experience of bender element transducers housed inside both the top cap and the pedestal of the triaxial cell, a novel technique is here presented, that allows velocity measures of seismic waves propagated through the triaxial specimen along horizontal and oblique directions. After a detailed description of the arrangement of the new transducers and of the testing methodology adopted, it is shown that this technique has the same degree of reliability and offers the same interpretation difficulty as the previously adopted ones. The application fields concern the evaluation of inherent and stress-induced anisotropy of triaxial soil specimens and the determination of the five independent parameters of the stiffness matrix of the cross anisotropic elastic model that seems to reproduce well the behavior of reconstituted Ticino sand within the small strain elastic region.