Stone Columns Field Test: Monitoring Data and Numerical Analyses

Abstract

This paper presents a case study of a field test performed on a set of 16 stone columns (4 × 4 square mesh, 1.85 m spacing, 1.0 m diameter, and 11.25 m length) loaded with iron rails applied during approximately one month. Extensive instrumentation comprising 28 instruments was used for monitoring the field test area. The objective of this study was to verify the performance of foundation improvements with stone columns for a future ore stockyard. The field test was also useful to calibrate a numerical model for predicting the behaviour of the permanent stockyard. Two- and three-dimensional finite element analyses were carried out and the results of field measurements and numerical calculations were compared. In general the numerical calculations of vertical and horizontal displacements reproduced the field measurements with satisfactory accuracy up to limit state conditions. Calculations of excess pore pressure and total horizontal stresses had less satisfactory agreement, and some reasons are provided for this. The yield of stone columns provided by 3D analysis appears to be more realistic than that provided by 2D analysis.