Bench-Scale Test Apparatus for Modeling Column-Supported Embankments: Fid-Bau Portal

Bench-Scale Test Apparatus for Modeling Column-Supported Embankments

McGuire, Michael P

Column-supported embankments (CSEs) with or without basal geosynthetic reinforcement can be used in soft ground conditions to reduce settlement by transferring the embankment load to the columns through stress redistribution above and below the foundation subgrade level. CSEs are typically used to accelerate construction and protect adjacent facilities from settlement induced by the new embankment load. Mobilization of load-transfer mechanisms to the columns in a CSE requires differential settlement at the base of the embankment. When the embankment height is low relative to the clear spacing between columns, poor ride quality can occur because of unsatisfactory differential settlement at the surface of the embankment that result from differential settlements at the base of the embankment. Currently, there is no widespread consensus on the minimum embankment height required to avoid this type of distress. This paper describes a bench-scale test apparatus, materials, test procedures, and instrumentation that were used to improve understanding of how factors such as the spacing between columns, column diameter, presence and tensile stiffness of geosynthetic reinforcement, and loading on the embankment surface affect settlement at the surface of the embankment in response to differential settlement at the base of the embankment. The results of one test performed using a single column, and one test performed using a 5 by 5 square array of columns are presented to illustrate the type of information that can be obtained using the apparatus. Future publications will synthesize the results obtained from the testing program and provide recommendations for CSE design.