Theoretical Solution for Long-Term Settlement of a Large Step-Tapered Hollow Pile in Karst Topography

Abstract

The large step-tapered hollow (LSTH) pile is an invented foundation solution for critical infrastructures overlying difficult geological profiles. In this paper, the time-dependent load-transfer model and the theoretical solution for calculating the long-term settlement of the new pile were presented. Using FLAC3D software, the time-dependent bearing characteristics of an LSTH pile were analyzed. A time-dependent load-transfer model (LTM) was employed to describe the time-dependent disturbance characteristics of pile–soil interaction based on the disturbed state concept (DSC). Using this LTM, the relatively intact state was defined by the Kelvin constitutive model, while the fully adjusted state was described by the perfectly viscoplastic constitutive model. Based on the LTM and the governing equations for the pile–soil interaction, an analytical solution for the long-term settlement of the pile was established. The proposed method was verified by means of a case study. The proposed model can be used to describe the time-dependent disturbance characteristics of pile–soil interaction.