Moisture transfer in shale samples subjected to desaturation - re-saturation

The excavation of underground galleries is expected to create a damaged zone around the galleries. Additional damage could be induced by the desaturation-re-saturation due to the ventilation in galleries. Desaturation induced cracks have already been observed in the Tournemire shale (France) and break-up of shot-crete in the reconnaissance gallery has been caused by swelling of Opalinus clay (Switzerland) around borehole collars. The assessment of the damaged zone is of main importance to estimate the retention capacity of rock mass. The first step of understanding such as process consist s in studying the moisture transfer in rock samples, in order to access to the mass transfer kinetics and to the spatial extension of the unsaturated zone. (authors)