Measuring Anisotropic Elastic Properties of Sand Using a Large Triaxial Specimen
An advanced automated triaxial testing system developed to characterize elastic behavior of soils is described. Small axial and lateral strains of a large rectangular prismatic specimen were measured locally at various stress states along a specified stress path, which was achieved by automatically controlling axial load and confining pressure. Elastic deformation was measured by applying very small cycles of axial or lateral stress at each given neutral stress state. Typical test data for air-dried sand are presented. It is observed that the elastic Young´s modulus is a rather unique function of the normal stress in the direction of the major principal strain increment, and therefore elastic deformation characteristics of sand become anisotropic under anisotropic stress conditions.