A modified equal-strain solution for consolidation behavior of composite foundation reinforced by precast concrete piles improved with cement-treated soil

Abstract

To effectively mobilize concrete strength, a newly developed composite pile, the so-called “Precast Concrete Piles Reinforced with Cement-treated soil (PCCS)”, has been used to improve the bearing capacity of soft ground. However, there are limited studies on the consolidation behavior of the PCCS in soft ground. This paper proposes an analytical solution for the consolidation of the composite ground reinforced by PCCSs based on a modified equal strain assumption. This composite ground is simplified as a double-layered consolidation ground according to the geometrical configuration of the PCCS. Subsequently, the analytical expression of the average consolidation degree is derived by considering the pile pierced into the gravel cushion and the additional stress that varies with time and depth. The accuracy of the proposed solution for consolidation is compared and validated by numerical analysis and current calculation methods. Furthermore, a parametric analysis is conducted to systematically investigate the influence factors of replacement ratio, core length ratio, modulus ratio of inner core-soil, modulus ratio of inner-outer core, modulus ratio of cushion-soil, permeability coefficient ratio and loading period on the consolidation behaviors of PCCSs reinforced ground. The proposed solution provides a theoretical guideline available for calculating the long-term settlements of such composite piled foundation.