3D numerical analysis of time effect of superstructure-piled raft-foundation

In coastal areas,piled raft foundations are widely employed for high-rise or multi-rise structures.Under such conditions,the effect of consolidation of soft soil ground on the interaction between piled rafts and foundation as well as superstructures can not be overlooked.Furthermore,both conventional methods of structural design and numerical procedures of two-dimensional interaction analysis can not realistically simulate the mechanism of interaction system without considering effect of superstructure stiffness.In order to well understand long-term behaviour of the interaction system,nonlinear deformation and strength behaviour of foundation soils were taken into account by using the elasto-plastic constitutive model based on Mohr-Coulomb’s yield criterion while the consolidation effect of subsoil under loading was incorporated by numerically solving Biot’s equations of consolidation in FEM formulations.Based on a case study for a given typical interaction system and comparative analysis for different cases,the features of variation of internal forces,settlement and compatibility mechanism of interaction system with time were examined.It was shown that both the consolidation characteristics of foundation and the superstructure stiffness remarkably affected time-dependent performance of the interaction system.Such dependency was intimately related to variation of excess pore water pressure of subsoil.It was indicated that both the effect of consolidation of subsoil and the superstructure stiffness on interaction behavior should be take into account in coupling analysis of superstructure-piled raft-foundation in order to well estimate the internal forces and deformations.