Numerical Solution of Stone Column–Improved Soft Soil Considering Arching, Clogging, and Smear Effects

Abstract

Improvement of soft clay deposits by the installation of stone columns is one of the most popular techniques followed worldwide. The stone columns not only act as reinforcing material increasing the overall strength and stiffness of the compressible soft soil, but they also promote consolidation through effective drainage. The analytical and numerical solutions available for ascertaining the response of column-reinforced soil have been developed on the basis of the equal strain hypothesis. For typical surcharge (embankment) loading, the free strain analysis appears to give more realistic results comparable to field data. The paper presents a novel numerical model (finite-difference method) to analyze the response of stone column–reinforced soft soil under embankment loading, adopting the free strain approach and considering both arching and clogging effects. Apart from predicting the dissipation of excess pore water pressure and the resulting consolidation settlement with time, the load transfer mechanism and the extent of ground improvement are some of the salient features captured by the proposed model. The proposed model is validated by comparing with existing models and field data, which indicate the suitability and accuracy of the solutions. The proposed model is also applied successfully to selected case studies.