Anisotropic stiffness measurements in a stress-path triaxial cell

Anisotropy plays a significant role in many geotechnical problems. This paper describes how the anisotropic stiffness properties of soils may be assessed through stress path triaxial tests. Local strain instrumentation has been optimised to identify the linear elastic region of sand without sacrificing the ability to study behavior at strains up to 15%; the system described performs equally well with sands, silts and clays. A novel technique has been developed in which multi-directional shear wave velocity measurements are combined with static tests to provide a complete description of the soil's cross-anisotropic elastic properties through a simple manipulation of classical elastic theory, Results obtained in tests on a dense sand are presented to demonstrate the system capabilities, show how the theoretical approach may be applied in practice, and draw attention to some interesting features of the soil's elastic anisotropy.