Tests on Cohesionless Materials for Rockfill Dams

An account is given of the tests carried out at the ISMES laboratories to set up techniques for testing cohesionless rockfill dam materials. A newly devised chamber formed of alternating rigid and deformable rings for confined compression tests is described. The chamber permits removing the disturbance due to surface friction and determining the vertical deformation under uniformly distributed load. The fundamental parameters affecting the compression of the material, such as grain-size curve, shape coefficient and degree of initial consolidation, are examined. Moreover, it outlines the possibilities of systematic research on homogeneous granulated materials when geometrically reduced grain-size curves are used. Consideration is given to the ratio between the size of the material and of the system (scale effect), showing the results of tests on specimens. Reproduction experimentation on reduced-scale models in accordance with the mechanical similitude of the entire system are strongly recommended.