Determination of an equivalent continuum mechanical model for the fractured EDZ around underground galleries by homogenization

Abstract

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 a possible elaboration of the ECM based on theoretical homogenization methods. The ECM that is first established for plane fracture surfaces is then extended to curved, conical shape fracture surfaces based on some simplification assumptions. Stress and displacement fields have been compared around the EDZ by using the ECM in a numerical simulation or by introducing the fractures individually as discontinuities in the model. The results show that although the size of the EDZ is too small compared with that of the representative elementary volume considered in homogenization approaches, the ECM obtained in this way seems to reproduce a well fractured EDZ behaviour.