Use of shear wave velocity to assess Champlain marine clay fabric anisotropy

This paper investigates the anisotropic characteristics of Champlain marine clay soil using a combination of laboratory techniques. A modified oedometer cell with a piezoelectric ring actuator technique was used to measure shear wave velocity during consolidation stages. The axisymmetric design of the oedometer allowed for the determination of shear wave velocity in both the vertical and horizontal planes. The preliminary findings reveal that the sensitive marine clay is inherently anisotropic, with lower preconsolidation pressure for horizontally consolidated specimens and faster propagation of shear waves in the plane parallel to the bedding layer. High-precision strain gauges integrated into the consolidation ring were used to evaluate horizontal stress during the one-dimensional consolidation test. The ability to determine mean effective stress enables the normalization of shear wave velocities using this stress, providing more coherent empirical correlations in terms of shear wave velocity. Scanning electron microscopy was used to examine the microstructure of clay specimens, providing qualitative and quantitative insight into the restructuring and reorientation of clay platelets under consolidation stress. The consistency of the results through both micro and macro-scale analyses confirms the reliability of the experimental approach, highlighting its potential for future studies on the anisotropy of Champlain marine clay fabrics.