ABSTRACT:

Building a high embankment on soft alluvial deposits within the constraint of a short construction period has always posed challenges to geotechnical engineers. Other than stability, settlement of the embankment has to be controlled. In the construction of a bridge embankment project in Singapore, embankment piles were used to ensure the stability of an embankment during construction, and to reduce and control subsequent settlements of the embankment. A system of embankment piles, integrating a flat slab, capping beams and geotextile was constructed. The capping beam-pile system that was implemented differs from the conventional practice where piles with individual pile caps are used. The capping beams were constructed perpendicular to the longitudinal axis of the embankment. This paper describes the study on the load transfer of the road embankment supported on embankment piles. The loads on the capping beams and soft ground were recorded and compared with theoretical analyses, based on equilibrium of semicylindrical sand arches. The field results showed reasonable agreement with the theoretical model. The comparison between the field results is also discussed in the paper.

INTRODUCTION

Soft marine and peaty clays of very low shear strength and high compressibility have been posing numerous foundation problems in Singapore. Embankment fills on such clays are often associated with potentially large ground movements and stability problems. When an embankment is formed on these clays, which have very low shear strengths, the increased stresses in the soft soil strata may lead to a deep-seated slip failure, causing large ground deformations. Piles are sometimes used as a ground improvement technique, in order to support the embankment fill. With the partial weight transfer of the overburden, the stresses acting on the soft ground will be reduced, thereby leading to greater stability and less settlement of the embankment fill.

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