A new design method for a foundation on a soil reinforced by columns is described. A lower bound of the bearing capacity is determined within the framework of the yield design theory. It takes into account the three-dimensional nature of the problem and is applicable to a wide range of geometries. A parametric study on the improvement of the bearing capacity as a function of the proportion of reinforcement, and on the strength characteristics, is presented. A complete analytical solution is given for the strength of a composite cell subjected to a triaxial loading, which provides an insight into the reinforcement mechanism. Le présent article propose une méthode de dimensionnement d'une foundation sur un sol renforcé par colonnes, basée sur la théorie du calcul aà la rupture. Une borne inférieure de la capacité portante est obtenue en tenant compte de la nature tridimensionnelle de l'ouvrage. Elle est applicable pour une grande variété de géométries. On présente une étude paramétrique sur l'amélioration de la capacité portante en fonction de la proportion de renforcement et des caractéristiques du matériau renforcant et du matériau initial. On s'intéresse en outre à la résistance en compression d'une éprouvette composite soumise à un chargement triaxial classique, pour laquelle une solution complete est fournie sous forme analytique. Elle apporte un éclairage intéressant sur le mécanisme du renforcement par colonnes.

This study applies the limit analysis to estimate the bearing capacity of a rigid foundation on a soil reinforced by a group of floating columns. The lower bounds of the bearing capacity are derived in terms of a dimensionless factor that depends on the characteristics of the soil and the inclusion, the area replacement ratio, the columns length, and a uniform surcharge surrounding the foundation. The established results are valid for a variety of reinforcing configurations in terms of arbitrary foundation shape and any randomly distributed column arrangements under the foundation. The computation of the bearing capacity is extended to the kinematic approach of the limit analysis for reinforcement of purely cohesive soils. For symmetrical column arrangement the upper bound of bearing capacity factor is calculated by the Prandtl’s mechanism failure. Previous results established for the reinforcement case by end-bearing columns remain valid when considering floating columns. Nevertheless, a limitation on th...

The installation of stone columns is widely adopted to prevent liquefaction. The main improvement mechanisms of stone columns as a liquefaction countermeasure are drainage, stiffening, and densification. This paper investigates the effectiveness of stone columns as a liquefaction remediation. Twenty-four case studies, in which SPT and CPT tests are performed before and after stone column reinforcement, are used as a basis of the research. Densification and stiffening mechanisms are investigated and their individual and combined effects are analyzed. Comparative results indicate that considering the densification and stiffening effects considerably improve the assessment of liquefaction potential of reinforced soil by stone columns.