Ground Improvement Utilizing Vibro-Concrete Columns

The use of Vibro-Concrete Columns (VCC) to improve soft ground is growing in popularity in various parts of the world due to its cost effectiveness and proven performance. A case history involving the first use of VCC by a US Department of Transportation to support an approach embankment is presented. The project involves the installation of VCC supporting 10 m high back-to-back mechanically stabilized earth walls underlain by a geotextile-reinforced sand platform. The design concept of the embankment supporting system is outlined. Static load tests results performed on two VCC are also presented and the acceptance criteria are discussed. The performance of the embankment supporting system is assessed based on monitoring data obtained from various instruments installed during construction including settlement platforms, probe extensometers, inclinometers, piezometers and strain gages attached to the sand platform geotextile reinforcing elements. Finally, recommendations are presented regarding the design aspects of the VCC and the geotextile-reinforced sand platform.