Résumé
We present 2 geomechanical approaches to better characterizing 3-D structural models by bringing rational physical principles to the geological interpretation. The first one is a 3-D slip-inversion method based on the analytical solution of an angular dislocation in a linear-elastic, homogeneous, isotropic, half-space. The approach uses the boundary element method (BEM) that employs planar triangular elements to model complex fault surfaces. Slip inversion techniques, usually used by geophysicists to invert for coseismic slip associated with earthquakes, are used here to determine the characteristics of faults, where they are poorly imaged. We have tested the method on a field case study from the Bishop Tuff, California, where the unseen 3-D fault geometries and slip distributions have been predicted using the only available data; (i) the fault pattern (fault trace map) and, (ii) the measured surface deformation (structure contour map). The second technique is based on the restoration of interpreted geological structures. The method, based on the finite element method (FEM), allows unfolding and unfaulting complex 2-D and 3-D structures using the physical behavior of rock mass and taking into account rock heterogeneous mechanical properties as well as physical boundary conditions. New algorithms have been developed to automatically correct the interpreted structures in zones that exhibit anomalous stress and/or strain concentrations subsequent to restoration. The technique has been tested on several 2-D and 3-D cases and we show how such geomechanically-based restoration can lead to better characterization of structural models.