Comparative performances of two- and three-dimensional analyses of soil-cement mixing columns under an embankment load

Abstract

This research presents measurements and simulations of the full-scale behavior of a test embankment built on a soft marine clay deposit improved using soil–cement mixing (SCM) columns in Bangkok, Thailand, using both two-dimensional (2D) and 3D finite element analyses (FEAs). Fixed SCM columns with two different installation patterns, that is, column groups and column rows, were constructed in the soft clay foundation prior to the construction of the embankment. Three column wall methods, namely, equivalent width, equivalent axial rigidity, and equivalent flexural rigidity approaches, were used to convert the 3D individual columns into 2D plane strain column walls. A comparison of the results obtained through the 3D and 2D FEAs revealed that the 2D analyses provide inaccurate results in terms of the column lateral movements, bending moments, and axial loads induced in the SCM columns in addition to the factors of safety against slope failure. This outcome occurred because the actual columns in the 2D FEA were modeled using extended walls, which essentially prevent the movements of soil between two columns or column rows. Correction factors used to convert the 2D analysis results into 3D analysis results were also proposed in this study.