An elastoplastic homogenization procedure for predicting the settlement of a foundation on a soil reinforced by columns

This paper presents an elastoplastic homogenization method applied to a soil reinforced by regularly distributed columns. According to this method, the composite reinforced soil is regarded, from a macroscopic point of view, as a homogeneous anisotropic continuous medium, the elastic as well as plastic properties of which can be obtained from the solution to an auxiliary problem attached to the reinforced soil representative cell. Based upon an approximate solution to this problem, in which piecewise constant stress fields are used, the homogenized behavior of the reinforced soil subject to vertical oedometric conditions is investigated. A first application to the evaluation of the settlement of a reinforced soil foundation is then presented, taking into account the initial stress field generated by the reinforced soil own weight. A particular emphasis is put on the situation of a purely cohesive soft clay reinforced by purely frictional inclusions (“stone column” reinforcement technique), for which a simplified calculation procedure, in which the soil remains elastic, is proposed, leading to an analytical closed-form expression for the load–settlement curve.