Abstract :
[en] Excavation damaged zone, with significant irreversible deformations and nonnegligible changes in flow
and transport properties generally occurs in indurated clay around underground structures. The stress
perturbation around the excavation could lead to a significant increase of the permeability physically
due to diffuse and/or localized microcracks growth in the material. In the present study, we investigate
microcracks-induced damage processes together with the subsequent modification in permeability. The
proposed approach is based on a homogenization-based upper bound extended to the context of micro-cracked media in presence of initial stress. Application of this approach is done on a borehole excavation
problem related to the Selfrac in situ experiments on Opalinus Clay. Although, the model fails to quan-titatively account for the in situ permeability change (which may also originated from existing macro-fractures), its prediction shows a significant evolution of the material permeability around the
borehole. This is in qualitative agreement with available data.
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