Abstract
Paying attention to the important mechanical features peculiar to granular materials : friction and dilatancy, fundamental considerations on the deformation of sand under simple shear condition are made. First, adopting the simple sliding block theory, the two state functions of ψ and S are analitically derived and a basic deformation model is formulated. This simple model is found to be a good approximation in the intermediate range of stress ratio. Next, using the experimental data, the entropy of granular materials S is examined. Another deformation model based on the characteristics of the state parameter S can be extended to wider range of stress ratios.
