Poroelastic parameters of Meuse/Haute Marne argillites: effect of loading and saturation states

Abstract

The aim of this paper is to summarize the experimental work carried out by IFP on rock samples taken from the Meuse/Haute Marne underground research laboratory host formation. The behavior of this clayey rock, called “argillite,” has been studied within the framework of Biot's mechanics of fluid saturated porous solids. Drained and undrained oedometric tests (i.e., uniaxial strain tests) have been performed to determine the poroelastic parameters for different stress levels. As the provided samples were not fully water-saturated, particular care has been taken over the definition of a preliminary resaturation phase and the estimation of each sample's final saturation level. Argillites poromechanical behavior appears to depend on the rock saturation state. Samples with a greater initial saturation seem to show a less apparent degree of overconsolidation and a higher compressibility. The obtained results also show the influence of the applied stress on the poroelastic parameters. Biot's coefficient decreases when the axial stress increases, while the drained bulk modulus and the shear modulus increase. The effect of the applied stress on Biot's modulus is more difficult to explain because its measure strongly depends on the saturation level of the sample.