ABSTRACT:

Two case studies of embankment failure at a reclaimed site in Singapore were carried out. Both the limit equilibrium slip surface method and the finite element method were employed in the studies. The analysis indicated that the critical fill height predicted by the limit equilibrium method was affected by the shear strength of the embankment fill, whereas that assessed from the finite element analysis was controlled by the input parameters of the foundation soil. Both the limit equilibrium method and the finite element method give reasonable prediction of the critical fill height when proper soil parameters and slope are chosen. The finite element analysis provides a better prediction of the actual slip surface than the limit equilibrium analysis.

INTRODUCTION

Limited land space in many countries in the East and Southeast Asian region has led to extensive foreshore land reclamation for diverse uses. In the planning and design of land reclamation, the stability of the fill resting on foundation soils is important. However, the analysis method provides no information on the change of stress and strain in the soil. For a detail understanding of the problem, the finite element method (FEM) may be useful. This paper describes two case studies involving embankment failure at a land reclamation site at Changi East in Singapore, one involving the placement of hydraulic sandfill and surcharge over a slurry-like soil mass in a silt pond and the other over a natural soft marine clay beneath the seabed. Both SSM and FEM are used in the analysis. A limit equilibrium based computer program PCSTABL developed at Purdue University is employed for the slip surface analysis. SAGE CRISP, a critical state finite element program developed by Sage Engineering and Cambridge University, is adopted for stress and deformation analyses.

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