An extension of rate and state theory to poromechanics

Abstract

Laboratory results on granular media have lead to fundamental theoretical developments (such as poroelasticity, rate- and state-variable friction) that have found widespread application. This paper presents results from laboratory experiments that help constrain and combine these theories. Data from triaxial deformation experiments on quartz sand aggregates are used to illustrate stress-dependent behavior of poroelastic parameters (e.g., the Biot-Willis coefficient). The results from both volumetric compaction and frictional shear experiments are well described by poroelasticity as well as rate- and state-variable friction. The combination of these constitutive relations may provide a powerful tool that can be used in numerical models that couple mechanical, hydraulic, and temporal processes in the descriptions of granular deformation. Copyright 2006 by the American Geophysical Union.