Sound speed in water-saturated glass beads as a function of frequency and porosity

TL;DR

This study investigates how sound speed in water-saturated glass bead sediments varies with frequency and porosity, providing experimental data and a Biot-based model to describe these dependencies.

Contribution

It offers new experimental data on sound speed variation with frequency and porosity in water-saturated glass beads and applies a Biot-based model for qualitative understanding.

Findings

Sound speed increases with frequency and decreases with porosity.

Experimental data covers 300-800 kHz frequencies and porosity 0.37-0.43.

Biot model qualitatively matches observed porosity dependence.

Abstract

Sound propagation in water-saturated granular sediments is known to depend on the sediment porosity, but few data in the literature address both the frequency and porosity dependency. To begin to address this deficiency, a fluidized bed technique was used to control the porosity of an artificial sediment composed of glass spheres of 265 {\mu}m diameter. Time-of-flight measurements and the Fourier phase technique were utilized to determine the sound speed for frequencies from 300 to 800 kHz and porosities from 0.37 to 0.43. A Biot-based model qualitatively describes the porosity dependence.