LOWER-BOUND APPROACH TO THE MACROSCOPIC S TRENGTH PROPERTIES OF A SOIL REINFORCED BY COLUMNS

The yield design homogenization method makes it possible to derive the global strength properties of a purely cohesive soil which has been r einforced hy a network of regularly spaced cylindrical inclusions made of a frictional material. Making use of the static approach, a lower bound estimate of this domain restricted to triaxial states of stress, which are axisymmetrical about the reinforcement direction, is obtain ed by using axisymmetrical stress fields over the unit representative cell of the reinforced soil. The results thus obtained highlight the t ruly three-dimensional nature of the problem and the shortcomings of t he multilayer model which is sometimes adopted for dealing with it.