In Situ Lateral Stress Coefficient (K_0) from Shear Wave Velocity Measurements in Soils

摘要

The at-rest lateral stress coefficient (K_0) is an important soil parameter in geotechnical design problems and yet it is quite elusive in our ability to assess its value, either by laboratory or in situ tests. In this study, an innovative geophysics approach toward the evaluation of the in situ K_0 profile with depth is obtained by using small-strain stiffness anisotropy ratio (G_(0,HH)/G_(0,VH)) in soils. The newly proposed K_0 equation is derived from a database compiled from 12 test sites which have direct K_0 measurements, as procured from field tests, either self-boring pressuremeters (SBP) or total stress cells (TSC), and/or laboratory triaxial tests, instrumented consolidometers, and/or suction measurements. The data show a strong relationship between the overconsolidation difference (OCD = σ_p~' - σ_(vo)~') and stiffness anisotropy ratio, thus enabling a K_0 assessment in clays, silts, and sands.