Acoustic inversion for Biot parameters in water-saturated sand

Abstract

Using an inversion of Biot’s theory, based on the formulation by Stoll, operative values of grain bulk modulus and the frame bulk and shear moduli of water-saturated sand may be extracted from measurements of compressional and shear wave speeds and reflection loss. The inversion process is nonlinear, but in practice it is well behaved and converges quite rapidly to unique values. The term grain bulk modulus, as defined in the formulation by Stoll, is not necessarily identical to the bulk modulus of the grain material, as is often assumed. Examples of the inversion will be given, and the significance of the operative values of the grain bulk modulus will be discussed. [Work supported by Office of Naval Research: Ocean Acoustics.]