Characterization of soil properties using elastic and electromagnetic waves

Abstract

Elastic and Electromagnetic waves provide important information about the soil mass in the near-surface. In order to facilitate the application of geophysical technique to soil characterization, experiments are performed for each wave. The first application is related to characterization of unsaturated particulate materials using shear wave. The small strain stiffness is continuously measured on specimens subjected to drying. Experimental results show that changes in stiffness are related to changes in interparticle forces such as capillarity, bonding due to ion sharing, buttress effect due to fine migration, cementation due to salt precipitation. Several phenomena associated with the evolution of capillary forces during drying are identified as well. The second application is relevant to the electromagnetic wave. A needle-size probe is developed to assess the spatial distribution of void ratio and other properties in laboratory specimens. Experimental results show that the spatial variability of void ratio affects shear strength so that not only mean void ratio but its variation should be considered in design analysis.