Limit Analysis of Rigid Foundations on Floating Columns

Abstract

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 the length of columns is required for some reinforcement cases. The reliability of the results of limit analysis is illustrated by comparison with two other published methods.