Mechanical behaviour of fine grained sediments: experimental compaction and three-dimensional constitutive model

Abstract

The usual undimensional description of deformations of sediments, based on a phenomenological relationship between porosity and the vertical effective stress, does not give information about the horizontal stress and, moreover, is irrelevant for sedimentary structures in which deformation process is not only vertical. Modelling three-dimensional deformation processes in sedimentary basins requires a three-dimensional mechanical constitutive model for sediments. A special œdometric cell was conceived in G.3S. This cell allows the measurement of the lateral stress during œdometric compaction and so enables us to elaborate a three-dimensional model of mechanical behaviour. Four varieties of fine-grained sediments were studied by this cell in a large scale of strain and stresses. The modified Cam-Clay model was used for fitting the experimental data and it was shown that this model can reproduce the mechanical compaction of sediments up to 50 MPa of vertical effective stress (about 3 km burial depth), if its parameters are deduced from œdometric (zero lateral strain) data.