Modern geotechnique raises a number of questions about soil mechanics, and many of these questions have still not been satisfactorily answered. Primarily, it bears on the load-holding capacity of deep foundations. The theory seems to be lagging behind, not only in working out methods for calculating bearing capacity and stability, but also in giving a theoretical explanation of such methods and technologies, namely the physical foundation for their influence on soil properties. During this time the awareness of soil interaction mechanisms has increased, and the realization of internal friction has come to be considered as the source of strength in non-cohesive mediums. However, it would be an exaggeration to state that the fundamental property of dilatancy has been fully represented in soil mechanics, especially in its use for the practical needs of geotechnics.