Simple Method to Predict Settlement of Composite Foundation under Embankment

Abstract

This paper presents a simple method to predict the settlement of the composite foundation with sparse prestressed tubular concrete (PTC) capped-piles under embankment. In this study, it is assumed that the distribution of skin frictions on PTC capped-piles is simplified as two force triangles, and a calculation model for predicting the additional stresses in the composite foundation soil is given. By combining Mindlin-Geddes and Boussinesq solutions, the equation of the additional stresses for a single PTC capped-pile foundation is derived considering the influence radius. A case history involving the installation of sparse PTC capped-piles for soil reinforcement under highway embankment is introduced, with a maximum settlement of 428 mm after construction. The predicted settlements of the composite foundation, resulting from the proposed method, are in good agreement with the observed data. Additionally, the additional stress field calculated shows a little change because the pile spacing is eight times larger than the pile diameter. Thus, the proposed method can optimize the design of the foundation soil reinforcement resulting from PTC piles.