Effect of partial drainage on plate anchor capacity in sand

Project Leader: Shiaohuey Chow
Collaborators: Asst/Prof Mason Ghafghazi (University of Toronto)
Primary Contact: Shiaohuey Chow (shiaohuey.chow@unimelb.edu.au)
Keywords: civil engineering; geotechnical engineering; numerical modelling
Disciplines: Infrastructure Engineering
Domains:

This is a joint PhD project based at the University of Melbourne with a minimum 20 month stay at University of Toronto. Expected start date is September 2021.

Supervision team

Dr Shiao Huey Chow (The University of Melbourne)

Assistant Professor Dr Mason Ghafghazi (University of Toronto)

Associate Professor Yinghui Tian (The University of Melbourne)

Project description

The recent growth in offshore floating renewable energy devices requires economic anchor solutions for sand. Plate anchors can represent such solution, although their response to realistic loading under offshore conditions still requires a more robust understanding, particularly under partially drained conditions imposed by rapid loading rates (e.g. under severe storm condition). Partial drainage (or the worst case scenario of undrained condition) occurs when the water in the porous sand skeleton is unable to drain away upon loading, resulting in a rapid increase of pore water pressure or generation of excess pore water pressures. The reduced drainage has a significant effect on the sand strength, which, in turn, affects the capacity of plate anchors. To date, there is limited numerical capability in simulating partially drained capacity of plate anchors in sand. The numerical modelling will be able to unveil the pore pressure distribution and failure mechanism during partially drained pull-out of the anchors – insights that underpin understanding but are difficult to obtain through other techniques.

This joint University of Melbourne (UoM) – University of Toronto (UoT) project aims to investigate effect of partial drainage on plate anchor capacity in sand using numerical and experimental approaches. The specific aims of this project, along with the research methodology and timeline/location of the research, are:

• To develop numerical modelling techniques that can address the full range of potential drainage conditions, and capture the effects of sand density and stress level. This will be achieved by implementing the NorSand constitutive model in a coupled analysis framework into finte element analysis using commerical software Abaqus. (Month 0 to 20 at Toronto, first 8 months for courseworks only)
• To perform numerical parametric study of strip anchors and circular plate anchors considering different embedment depths, sand densities and pull-out rates. (Month 21 to 48 at Melbourne)
• To perform experimental study of partially drained pull-out of strip and circular anchors considering different embedment depths, sand densities and vertical pull-out rates for validating the numerical study. (Month 21 to 48 at Melbourne)

The outcomes of the project will be integrated into an accessible design tool to enable better predictability of anchors capacity under partial drainage in sand in engineering practice.