Application of grouted gravel pile in soft subgrade improvement of expressway

Grouted gravel pile is a new technique of pile construction, load-bearing characteristics of grouted gravel pile composite foundation is analyzed based on its application to soft subgrade improvement of Ningbo round-city expressway. The settlement and lateral deformations of the subgrade are monitored in-situ; while the pore pressure, earth pressure between piles and pressure on the top of piles are also monitored. The monitor result indicates that: the total settlements are small and soon became stabilization, which is propitious for the construction; stress concentration on the top of piles is evident, which proved the replacement effect of pile is evident; pore pressure decreased soon, which reduced settlement after construction caused by secondary consolidation.