On the Post-peak Behaviour of Remoulded and Jointed Clay Samples During Triaxial Compression Tests

The note presents a selection of the results of a large experimental program conducted with the aim of characterizing the shear strength of Opalinus Clay and Speswhite Kaolin in remoulded and reconstituted conditions, through the execution of unconventional triaxial tests. The collected results clearly show the influence of the degree of pre-consolidation and the joints on the mechanical behaviour of the geomaterials, and in particular on the shear strength. The presence of pre-existing joints inside the specimen completely alters the original behaviour of the material, which becomes ductile and contracting. Moreover, interpreting the results with a sliding blocks model, it has been proved that, under these conditions, the shear strength can be drastically reduced to the residual strength values.