A reference state curve to define the state of soils over a wide range of pressures and densities

M. PASTOR; S. M. R. IMAM; D. MANZANAL; J. JAVANMARDI

GEOTECHNIQUE

THOMAS TELFORD PUBLISHING

Año: 2017 vol. 68 p. 95 - 106

0016-8505

Granular materials exhibit a behavior that is strongly dependent on density, effective confining pressure, and grain characteristics. The complexity is such that in the past, for a given sand, loose and dense specimens, or specimens subjected to very low or very high confining pressures were considered as different materials and were modeled as such, using different constitutive parameters. The introduction of the state parameter improved both understanding the behavior and modeling of granular materials. Several alternative definitions have been proposed for state parameter but they suffer from some limitations, especially when sand is very loose, has fines, or is subjected to high confining pressures. The purpose of this paper is to describe those deficiencies and to introduce a new state index based on a novel reference state curve. The proposed reference state curve is then applied to understanding and predicting some important aspects of soil behavior such as: (i) stress ratios at the peak point of undrained effective stress paths, (ii) the "reverse behavior" of sandy soils that show an unusual behavior in undrained shearing under high effective confining pressure.