A Case Study of Settlement and Load Transfer at Depth Beneath Column-Supported Embankments

Abstract

The use of column-support to facilitate rapid placement of fill over soft ground continues to gain wider acceptance and popularity. A soil arching mechanism and, often times, a geosynthetic reinforced load transfer platform partially transfers load to support columns beneath embankment and MSE wall fills. The mechanisms contributing to load transfer at the heads of columns has been the subject of extensive research for column-supported embankments. However, less attention has been given to the role of soil-column interaction at depth, and its influence on performance of these systems. This case study presents measured surface and subsurface deformations beneath embankments and retained MSE wall fills supported on concrete rigid inclusions. Movements were measured with settlement plates and extensometers. Stress changes beneath fill material was inferred from measured subsurface deformations and indicate soil-column interaction contributes to continued stress-reduction at depth. A quasi-3D finite element analysis was performed to examine the influence of soil-column interface shear strength in a near-surface layer of compressible clay. Computed results indicate soil-structure interaction in this layer plays an important role in the efficacy of settlement reduction, especially as clay thickness increases.