Abstract:
This study presents the design, optimization and construction process of Olivier inclusion ground improvement beneath two adjacent residential towers on Mt Wellington Highway in Auckland. An Olivier inclusion is a cast‑in‑place, full‑displacement element of concrete with a continuous helical shaft that transfers loads through a load transfer platform, which helps distribute forces between the inclusions and the soil. A fully coupled 3D finite element analysis using PLAXIS 3D was conducted, utilizing the Hardening Soil Model with Small Strain Stiffness, calibrated against site investigation data. The 3D analysis captured the interaction between the inclusions and each tower as well as the mutual interaction between the neighbouring towers. A parametric study of inclusion geometry, spacing, and embedment depth led to an optimized solution that met all design requirements while delivering a safe, sustainable, cost-effective, and innovative outcome. Additionally, load tests on inclusions of varying lengths were conducted to validate axial stiffness assumptions across different soil layers.