Design and Monitoring of an Embankment on Controlled Modulus Columns

Abstract

The controlled modulus columns (CMC) foundation is one technique of ground modification for support of light structures such as highway and railway embankments. In this technique, a specially designed auger, powered by equipment with large torque capacity and high static down thrust, displaces the soil laterally without vibration. During the auger extraction process, a column is developed by pressure grouting to achieve a predetermined stiffness ratio with the surrounding soil. Because of the combined effect of densification and reinforcement, the properties of soft soil are improved because of composite action. The design and monitoring of a column-supported embankment project are presented; 2,193 CMC columns were installed up to a depth of 12.5 m to control settlement. The main challenges were construction on soft ground and the need for an accelerated construction technology for timely delivery of the project. Various alternatives, stability analysis, design considerations, construction challenges, quality control, and monitoring system were evaluated.