ABSTRACT:

A novel plane strain approach is introduced to model the behaviour of embankment foundations on soft clay stabilised with vertical drains, where the classical axisymmetric solutions are converted to an equivalent plane strain model, incorporating the effects of smear and well resistance. This paper describes the behaviour of an embankment stabilised with vertical drains, where a specific case history is selected from Malaysia. The consolidation of soft clay is modelled on the basis of the modified Cam-clay. The settlement behaviour at various stages of embankment loading is analysed using the finite element technique, and the numerical results are compared with field measurements. The behaviour of drains with and without smear is also compared. Inclusion of smear effect in the mathematical model improves the prediction of settlements.

INTRODUCTION

The deformations of soft clay foundations stabilised with vertical band drains has remained difficult to predict accurately, although a significant progress has been made in the past few years through rigorous numerical modeling. Attributed to the rapid development in computer technology and the increasing versatility of the finite element method, a thorough numerical analysis of the settlement of the soft soil stabilised with multiple vertical drains can now be conducted. Following previous developments (e.g. Cheung et al., 1991; Hird et al., 1992), Indraratna and Redana (1997) extended the analysis based on the plane strain solution to include explicitly the effects of smear and well resistance. Although a single-drain analysis is often performed to model the soil behaviour along the embankment centerline (symmetric geometry), multi-drain analysis is essential to study the overall behaviour of a soft clay foundation underneath the embankment. This paper presents a plane strain, multi-drain analysis for a selected case history from Malaysia, along the North-South Expressway built on the Muar coastal plain.

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