Yield stress history evaluated from paired in-situ shear moduli of different modes

A special compiled database of shear moduli from different directional and polarization modes (HH, HV, and VH waves) at well-documented geologic sites shows that stiffness ratio (G0,HH/G0,VH) can be used to assess the yield stress ratio (YSR) in soils. In general, the reference profiles of YSR for these sites were determined using series of laboratory consolidation tests on undisturbed samples at varied elevations, coupled with a good understanding of the engineering geology background of the formations. For stress history assessment in soils, various empirical correlations were derived from multiple regression analyses using the stiffness ratio and additional variables.