A Semi-micro-mechanical model for Anisotropy of Sand

A semi-micro-mechanics approach can successfully model the stress-strain of sand once the macro-characteristics of the material have been employed. However, it is usually difficult to determine the fabric of natural sand under the effect of existing bedding plane. Anisotropy of sand is mainly due to the geometrical arrangement of particles that depends on the orientation of applied load respect to the bedding plane. It is geologically due to micro-fabric created by the arrangement of the particles configured during deposition. The employed multi-plane based model is capable of predicting the behaviour of soils on the basis of sliding mechanisms, elastic behaviour of particles and possibilities to see the micro-fabric effects as natural anisotropy as well as induced anisotropy. The model is capable of predicting the behaviour of soil under different orientation of bedding plane, history of strain progression during the application of any stress/strain paths. The influences induced anisotropy are included in a rational way without any additional hypotheses. The spatial strength distribution at a location as an approximation of probable mobilized sliding mechanism is proposed as a ellipsoid function built up on bedding plane. According to the proposed methodology the used parameters of this semi-micro-mechanical model are obtained through macro-mechanical test results. The results of model are well compared with experiments.

Keywords:

Semi-micro-mechanic Model , Multi-plane , Bedding plane , Fabric , Anisotropy