Mechanical testing of hollow cores to determine elastic parameters of anisotropic rocks using the CSIRO HI cell

Abstract : We present a new, iterative approach for determining the elastic parameters of transversely isotropic rocks, based on the mechanical testing and the numerical modeling of hollow cores. Cores recovered during overcoring were submitted to a given pressure on their external boundary while the strains were recorded within the inner hole by a CSIRO HI cell. The strains were also calculated numerically for different values of the elastic parameters of the rock, using a 3D finite element method. Charts were used for the graphical determination of the elastic parameters that allowthe closest modeling of the measured strains. Elastic parameters of the Tournemire argillite rock estimated by this method display a much lower anisotropy ratio than the one obtained from classical laboratory tests. The possible origin of this difference is discussed.