Modelling stone column installation in an elasto-viscoplastic soil

Abstract

The majority of numerical studies investigating stone column performance have used “wished-in-place” columns (no installation effects) in conjunction with elastoplastic soil models (no viscous effects). In the first part of this paper, cylindrical cavity expansion (CCE) is used in conjunction with the PLAXIS 2D elasto-viscoplastic soft soil creep (SSC) model to evaluate the effect of creep on column installation. Creep leads to lower post-installation lateral earth pressure coefficients (K) than if primary consolidation was considered alone, although the values of K/K0, which decay with distance from the column center, are nevertheless greater than 1·0. In the second part of this paper, two sets of unit cell analyses have been carried out to investigate the effect of accounting for column installation on subsequent settlement performance. The results indicate that “primary” settlement improvement factors are larger than “total” settlement improvement factors and that the relative differences between them increase when installation is taken into account.