Behaviors of rigid piles for reinforcing highway embankments in soft soils

Rigid piles have been widely used to reinforce highway embankments in soft soils due to their rapid construction, low costs, and small total and differential settlements, while their mechanism has been still incompletely understood till now. A numerical analysis is conducted to evaluate the variation of the soil stress concentration ratio, pile and soil settlements, pile shaft axial forces, negative skin friction and neutral plane for end-bearing piles as well as floating piles during the embankment filling and the consolidation of soft soils. The results indicate that the stress concentration ratio varies with the embankment filling and the consolidation of soft soils, and most of embankment load is born by the pile owing to that the pile stiffness is significantly greater than that of soft soils. The end-bearing pile settles a little and most of the settlement occurs during the embankment filling while the settlement of the floating pile is much greater and most of the settlement occurs during the soil consolidating. The settlement of most part of the end-bearing pile shaft is greater than that of the surrounding soil, but the settlements of most part of the floating pile shaft is less than that of the surrounding soil. The pile axial force and negative skin friction, for the end-bearing pile and the floating pile, develops more quickly during the embankment filling than during the soil consolidating. Negative skin friction develops along most part of the end-bearing pile shaft while only a small part for the floating pile. The location of the neutral plane exhibits a complicated variation.