Evaluating the shear strength of a natural heterogeneous soil using reconstituted mixtures

This work originates from the need to provide the geotechnical characterisation of a natural heterogeneous soil outcropping along a landslide-prone hillside. The soil, geologically identified as highly tectonised phyllite, results from the large tectonic strain deformation of the original weak rock, which produced a melange of grain particles enclosed in a fine matrix. This study investigates the possibility of estimating the shear strength using the framework established for binary mixtures to overcome the difficulties of undisturbed sampling. Two main problems were tackled: the identification of the matrix fraction in well-graded mixtures and the effect of variation in the grading of the granular fraction.