Determination of Shear-Wave Velocities and Shear Moduli of Completely Decomposed Tuff

Abstract

Based on theoretical derivations and considerations, five series of laboratory tests were planned to investigate and differentiate the degrees of inherent and stress-induced anisotropy, to study the effect of void ratio changes on shear-wave velocities and shear moduli, and to determine the relationship between shear-wave velocity and stress state on a completely decomposed tuff (CDT). Shear-wave velocities in three orthogonal horizontal and vertical planes [ vs(hh) , vs(hv) , and vs(vh) ] were measured in both vertically and horizontally cut block and Mazier specimens. Under isotropic stress conditions (K=1.0) , the degrees of inherent anisotropy [ vs(hh) 2 ∕ vs(hv) 2 = Ghh ∕ Ghv ] were 1.48 and 1.36 for the block and Mazier specimens, respectively. At the anisotropic stress state (K=0.4) , the degrees of anisotropy of the block and Mazier specimens were 1.26 and 1.15, respectively, 15% reduction from the measured inherent anisotropy due to stress-induced effects. The measured higher shear-wave velocity ...