Investigation of the Load–Settlement Response of Piles in Sand Using an Interface Constitutive Model

A semianalytical approach has been developed to investigate the nonlinear load–settlement behavior of bored single piles and pile groups embedded in sands. A more rigorous load-transfer function for the pile shaft, adopted to describe the pile–soil interface behavior, is derived from a damage constitutive model of the soil–structure interface. The interface model employed is capable of capturing the strain-hardening/softening and bulk dilatancy properties of the pile–soil interface and reflecting the degradation of the pile shaft skin friction. Meanwhile, an existing analytical solution has been applied to approximately describe the elastic stress–displacement relationship of soils outside the pile–soil interface during shearing. Moreover, the nonlinear stress–displacement relationship of soils at the pile base is simulated by a hyperbolic model considering the particle-crushing behavior of soils. Model parameters can easily be calibrated from laboratory interface shear tests and the physical properties of soils. Based on the matrix displacement method, the governing equation of the load–settlement response for bored piles is computed via an efficient iterative algorithm developed in terms of the midpoint incremental method. The pile-to-pile elastic interaction and the reinforcement effect of neighboring piles are incorporated into the investigation of pile groups. The present approach is verified by comparison with the existing theoretical approach, centrifuge tests, and model pile tests. Extensive parameter investigations are performed to systematically explore the load–settlement response of the single pile and pile groups.