The dynamic shear modulus of marine sediments

Abstract

The dynamic shear modulus of marine sediments (μ) as a function of overburden pressure (p) and voids ratio (e) can be represented approximately by the expression μ=μ0(p/p0)n ×exp(−Γe), where μ0, n, and Γ are constants. Available laboratory results for sands, silts, and clays over a pressure range of 24 to 700 kPa and a voids ratio range of 0.35 to 1.5 lead to the values: n=0.45, Γ=1.50 and, if p0 is taken as 1 atm, μ0=2526 atm. For bentonite, an expandable clay with high cation-exchange capacity, the voids ratio dependence is similar (Γ=1.60) but the pressure has relatively little effect (n=0.08). Secondary effects due to quasistatic stress history and dynamic shear strain amplitude may modify these values somewhat for low-amplitude acoustic signals in in situ sediments.