Determination of Equivalent Continuum Mechanical Model for Fractured EDZ Around Underground Galleries by Homogenization

An Equivalent Continuum Model (ECM) is proposed in order to represent the hydromechanical behaviour of the fractured Excavation Damaged Zone (EDZ) around deep underground galleries excavated in claystone. The fractures observed in these galleries show a regular trend that makes possible elaboration of ECM based on theoretical homogenization methods. The ECM established first for plane fracture surfaces is then extended to curved, conical shape, fractures surfaces based on some simplification assumptions. The stress and displacement fields have been compared around the EDZ by using the ECM in numerical simulation or by introducing the fractures individually as discontinuities in the model. The results show that however the size of EDZ is too small compared to that of Representative Elementary Volume (REV) considered in homogenization approaches, the ECM obtained in this way seems reproducing well the fractured EDZ behaviour.