Time dependency behavior of granular materials

Theory of elasticity is the most used assumption in pavement design. Highway materials are neither elastic nor homogenous. Therefore there is a need for models which are based on more realistic assumptions. UGM shows time dependency in nature. This is reflected in a viscous response close to the surface and an elastic response deeper down the construction. Time dependencies of soils are relatively studied phenomena and well known to researchers but not fully regarded as a problem in civil engineering. A limited number of models are suggested to describe time related deformation of soils and unbound granular materials in particular. In this study a large box, 800*800 mm is used where the confining pressure will increase with depth from the surface as in real constructions. The behavior of some granular materials subjected to dynamic loadings is studied. The results indicate that the time of loading affects the permanent deformation.