EXPERIMENTAL-ANALYSIS OF THE EFFECTS OF FLUID-SOLID COUPLING ON THE VELOCITY OF ELASTIC-WAVES IN SATURATED POROUS-MEDIA

This paper briefly reviews the characteristics of fluid-solid coupling in the dynamic behaviour of saturated porous media and describes the installation and use of piezoceramic transducers for the simultaneous measurement of longitudinal and rotational waves in triaxial samples, The comparison between longitudinal and rotational wave velocities mea sured in dry and water-saturated samples is described and analysed in detail. Two soils with different permeability features are investigate d, The comparison shows that a reliable interpretation of rotational w ave velocities of both permeable and impermeable saturated soils can b e obtained if the effects of viscous and inertial couplings are taken into account using Biot's theory, The same conclusions apply to the lo ngitudinal wave velocities of impermeable saturated soils, In contrast , the interpretation of longitudinal wave velocities of permeable satu rated soils gives an elastic stiffness value which is underestimated w ith respect to the value obtained from dry soils, Finally, the accurac y with which the small-strain stiffness of saturated soils can be eval uated from dynamic tests is discussed.