Introduction to the yield design theory and its applications to soil mechanics

The design of new types of earth structures using recent industrial techniques as soil reinforcement, soil nailing, etc., makes it desirable to overcome some mechanical inconsistencies which may still be encountered in current stability analysis methods. The paper is devoted to a presentation of the yield design approaches starting from the obvious necessary stability condition that the equilibrium of the considered structure and the resistance of the constitutive soil should be compatible. The static approach of the yield design theory follows directly from this condition, leading to lower estimates of the extreme loads. It is shown that the corresponding kinematic approach must be derived by dualizing the static approach through the principle of virtual work so that mechanical consistency is ensured: the concept of maximum resisting work is introduced and the method can be efficiently used to obtain upper bound estimates for the extreme loads. Most of the arguments of the paper are developed for a classical stability analysis problem, making it possible to illustrate the theoretical concepts and to thoroughly examine the practical implementation of the methods. Various fields of applications are finally surveyed