Abstract:
An idealized model of the poroelasticity of dry- and water-saturated sand is hypothesized. The model addresses the nature of the grain--grain contact, and it is based on frame shear and bulk moduli inverted from measured acoustic and shear wave speeds as a function of pressure. The experimental data are from E. Hamilton [J. Geophys. Res. 76, 579--605 (1971)] in which both the compressional and shear wave speeds were measured as a function of the differential pressure in dry- and brine-saturated sand sediments of grains sizes approximately 0.137 and 0.7 mm. The inversion is based on Biot's theory. The results suggest quantifiable effects due to adhesion between grains and pore fluid, partial lubrication of the grain--grain contact by the pore fluid, and a solid grain--grain contact area that changes with applied pressure. [Work supported by ONR, Code 321 OA.]