Combined electrical resistivity-shear wave velocity-based characterisation of a sand

The mechanical behavior of a soil, including shear strength, is primarily controlled by the soil's density (void ratio) and stiffness, in addition to effective stress. The development of a 15 cm in diameter instrumented triaxial cell is described in this study which allows the measurements of electrical resistivity (b) and shear wave velocity of a soil sample. This is used to measure and Vs of a silica sand. A triaxial system is used to saturate and consolidate the sand sample. Results show that while effective stress has a significant effect on Vs , b sharply rises with increasing specimen's density (irrespective of effective stress) as the volume of pore spaces containing the electrolyte solution decreases. Empirical correlations are developed between the formation factor (FF), i.e., b normalized by pore fluid electrical resistivity, and the overburden stress-normalized Vs , as well as between FF and soil unit weight and relative density.