Failure in geomaterials: continuous and discrete analyses

Various modes of failure in geomaterials have been observed in practice. Different criteria have been proposed to analyse these failures. In particular, Hill's Condition of Stability and diffuse modes of failure are considered in this paper in a dual framework: continuum mechanics and discrete mechanics. With the assumption of continuous media, experiments have shown that q constant loading paths (q characterizes the second stress invariant. For axisymmetric conditions, q is equal to: q = sigma(1) - sigma(3), where sigma(1) is the axial stress and sigma(3) the lateral stress) can exhibit non-localized failure modes and are analyzed by the second order work criterion. With the assumption of discrete media, grain avalanches are considered, and spatial and temporal correlations between bursts of kinetic energy and peaks of negative values of second order work are demonstrated from discrete computations. It is concluded that the second order work criterion (under its dual form: continuous and discrete) can be a proper tool to analyse diffuse modes of failure in geomaterials.

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