REPEATED LOAD TRIAXIAL TESTING OF GRANULAR MATERIALS IN THE FRENCH NETWORK OF LABORATORIES DES PONTS ET CHAUSSEES

This paper presents some methods developed in the past ten years in France by the Laboratoires des Ponts et Chaussees (LPCs) for studying the mechanical behaviour of unbound granular materials. The first part of the paper describes the equipment and test procedures used for these studies. The LPCs have designed a repeated load triaxial apparatus for unbound granular materials, with a specimen size of 160 mm in diameter by 320 mm in height. This apparatus uses a pneumatic loading system, capable of cycling both the axial load and the cell pressure. Two different test procedures are used: a procedure for studying the permanent strains of the material, and a procedure for studying its resilient (elastic) behaviour. Finally, the paper presents some models used to describe the resilient behaviour and the permanent strains, and examples of their application. (A) For the covering abstract see IRRD 883133.