Microstructure influence on soil behaviour at small strains

Mechanical properties of soils are mainly related to their microstructure. Triaxial tests with local strain measurements were performed on various types of soils in order to determine their behaviour in the elastic domain. In granular media physical parameters representative of the grains, such as shape, size, mineralogy, can be connected to the ones describing their assembly: void ratio, anisotropy, to explain the behaviour of the equivalent continuous medium. In clayey materials the description of the microstructure is more complicated and has to be examined at different scales. Comparison between intact and remoulded samples can contribute to explain the influence of the geological history and the mode of deposition on the mechanical properties at small strains.