Correction for a Wide Range of Sediments

Abstract

The Extended Biot (EB) model for sandy seabeds is improved with the aid of the Revil, Glover, Pezard, and Zamora (RGPZ) model. The RGPZ model provides a direct link between the mean grain diameter and porosity, which is the primary means of sediment classification, and the input parameters of the EB model. The difficult-to-measure parameters, such as permeability, pore size, and tortuosity, are replaced by relationships based on mean grain size, porosity, and a couple of well-bounded dimensionless parameters: cementation exponent and pore shape parameter. The combined RGPZ and EB (REB) model is extended to silts and clays. Regarding the frame moduli, one modification to the model was necessary. In the EB model, the relationship between grain-contact stiffnesses at the microscopic scale and the macroscopic frame moduli was based on a model of randomly packed spheres. A heuristic correction, based on porosity, was necessary to fit the observed relationships in silts and clays, which tend to have a flocculated structure, which is very different from randomly packed spheres. The corrected REB model (CREB) is able to model the wave speeds and absorptions of mono-sized, unconsolidated, and uncompacted sediments across the Wentworth scale, from pebbles through various grades of sands and silts to clays.