Strength-dilatancy of sands at low stress levels

PhD student

Mostafa Gholami

Supervisors

A/Prof Shiaohuey Chow	Dr Sanchari Mondal	Prof Mark Cassidy

Project Start Date: July 2024

Project Details

Shallow offshore foundations and near-seabed infrastructure mobilise soil shear strength at effective stress levels much lower than those commonly represented in laboratory databases used for conventional geotechnical design. At low stresses, the strength and dilatancy of sand is affected by density, stress level, and particle shape. Yet the combined influence of these factors is not adequately represented in existing design correlations, particularly for carbonate sands.

This project investigates the strength–dilatancy behaviour of sands at low effective stresses through a laboratory testing programme on different materials. These materials have contrasting particle shapes, enabling their effects on the shearing response to be examined. Particle-scale characterisation and advanced imaging help relate the macroscopic behaviour to soil fabric and particle interactions.

The experimental results are interpreted using critical-state and stress–dilatancy frameworks to evaluate the applicability of existing relationships at low stresses. The study provides new experimental evidence and practical guidance for deriving design-relevant strength and dilatancy parameters. The findings support more reliable characterisation of shallow seabed sands and the safer, more economical design of offshore energy infrastructure.