Mechanical characterization of matrix coarse-grained soils with a large-sized triaxial device

This paper presents an experimental program that characterizes the mechanical behavior of heterogeneous soils using a large-sized triaxial apparatus (300 mm diameter and 600 mm height). A particular class of heterogeneous soil called matrix coarse-grained soil, composed of a mixture of a sandy matrix (Fontainebleau sand) and inclusions (gravels), was studied. The experimental procedure to rebuild samples is presented first with a description of a typical test setup. A synthesis of the experimental results obtained is then presented. A particular focus is placed on studying the influence of basic soil parameters: the properties of the inclusions (volumetric fraction, particle size, grading parameter) and the initial state of stress in the soil. The two classical methods used to study the mechanical properties of matrix coarse-grained soils in the laboratory (clipping and clipping-substitution) are evaluated.