Three-dimensional large-strain consolidation considering creep behavior improved by vacuum preloading

The creep settlement in deep soft soil during consolidation is significant, rendering the classical small-strain consolidation theory inadequate. A three-dimensional large-deformation consolidation theory is proposed for soft soil under vacuum loading, accounting for creep. It incorporates the nonlinear variation of the creep index with preloading duration and overconsolidation ratio (OCR), alongside the nonlinear evolution of key parameters such as void ratio and permeability in vertical and radial directions. A governing equation for deep soft soil with drainage boards under vacuum loading is established and solved using the finite difference method. The validation against field-measured settlement and pore water pressure data from a ground treatment project in Tianjin confirms the reliability of the theory. The results show that the creep index exerts a greater influence on settlement and pore water pressure further from the drainage board. Preloading significantly reduces the post-construction creep settlement, while a higher OCR lowers the sensitivity of settlement to the creep index.