Understanding the response of saturated rock mass to pore pressure perturbations in processes such as nuclear waste disposal and petroleum resources exploitation requires the knowledge of effective stress as described by Biot's effective stress theory (Biot 1941). To date, more than ten experimental techniques for measuring Biot's effective stress coefficient (α) have been published. The objective of this study was to provide an overview of these techniques along with their applications to several cases. Current methods are based on different premises: dry and grain bulk moduli, bulk and pore volume change, isochoric compression, matching deformation or failure envelopes of dry and saturated samples, variations of rock properties (e.g. permeability, deformation, P-wave velocity) with respect to confining stress and pore pressure, estimation from other poroelastic properties, and approximations for dry and grain bulk moduli. Discussions are provided on factors affecting α such as pore characteristics, stress path, and test conditions.
Biot's effective stress theory (Biot 1941) facilitates study of the geomechanical impacts caused by pore pressure variations in rocks. Defined in Equation 1 is Biot's theory which partitions the total stress(σ)in the rock to effective stress (σ′) and pore pressure (P) multiplied by Biot's coefficient or effective stress coefficient (α). To date, various methods have been proposed to determine α.In this study, the original technique (proposed by Geerstma (1957) on empirical grounds) and its succeeding varieties, as applied to several rocks, were reviewed.
(equation 1)
Biot's effective stress theory (Biot 1941) facilitates study of the geomechanical impacts caused by pore pressure variations in rocks. Defined in Equation 1 is Biot's theory which partitions the total stress(σ)in the rock to effective stress (σ′) and pore pressure (P) multiplied by Biot's coefficient or effective stress coefficient (α). To date, various methods have been proposed to determine α.In this study, the original technique (proposed by Geerstma (1957) on empirical grounds) and its succeeding varieties, as applied to several rocks, were reviewed.
(equation 1)
