Evaluation of structural modification of a hard deep clayey rock due to wetting/drying cycles

Abstract : New wetting / drying tests including cycles effects were performed on the same argillaceous deep rocks coming from Callovo-Oxfordien deposit from eastern France. Bulk volume and water content were measured in order to estimate the importance of physical changes. Then mercury injection tests were performed on dry and wet samples in order to quantify the influence of hydraulic history on fracture. Results showed that shrinkage and swelling originated micro-cracks which led to important volume variations, and thus strongly altered structures and organizations of the rock. Mercury injection tests performed on wet samples equilibrated with different hygrométrie saline solutions allow describing unsaturated pores and complete classical water retention curves to explain changes in microstructure and related mechanical and physical properties.