Exploring the linkages between geotechnical properties and geophysical responses of unconsolidated materials - Laboratory measurements
Upon application of stress, the strength and stability of unconsolidated geo-materials are influenced by modifications of their micro-structure, texture and effective stress conditions. These modifications in earth's subsurface often result in geo-hazards (e.g., landslides, liquefaction, debris flow) which often claim so many lives, destroy the environment and cause considerable amounts of property damage. The fundamental relations between the geo-electrical parameters and the geotechnical properties characterizing sand-clay mixtures are investigated by performing controlled laboratory experiments. Spectral electrical response (SER) measurements are performed on these mixtures over a range of frequencies (0.001Hz-10kHz). Useful electrical parameters, that is, the phase, loss tangent and capacitance are extracted from the SER measurements. Relevant petrophysical/geotechnical parameters are obtained from the mixtures which include the void ratio, dry density and the modulus of elasticity. Cross-plots of geotechnical parameters and geo-electrical parameters indicate significant correlations. These relations can be useful in predicting the physical, mechanical and geotechnical properties of unconsolidated geo-materials in transition from frame-supported to suspensions or (from high to low effective stress).
