Abstract: Composite pile refers to a new pile type generated by two different materials through a dual construction way. The composite pile is composed of two materials with different properties, which play a complementary and reinforcing role. Taking the composite ground improved by the concrete-cored sand-shell composite piles as the research object, the composite pile is transformed into an equivalent ring element based on the principle of constant cross-sectional area and perimeter. The core-pile ratio, i.e., the ratio of the concrete core and composite pile cross-sectional area was introduced, and the construction disturbance and the depth-dependent stress increment caused by time-varying surcharge loading was considered. A consolidation analytical model of the composite ground with composite piles was proposed based on the equal strain assumption and the Darcy’s law. Furthermore, explicit solutions under four different load conditions were obtained. Finally, the consolidation behaviors of the composite foundation were investigated by a series of parameter sensitivity analysis. The results show that the hollow ratio of the square section pile is the smallest and the excess pore water pressure dissipates fastest among the square piles with a certain circumference. The foundation consolidation rate is positively correlated to the core-shell compression modulus ratio and permeability coefficient ratio. With the increase in the top load, the consolidation rate gradually increases.

Key words: composite foundation, composite pile, consolidation, profiled section, ring element