Development of a Soil-Specific CPT Interpretation Method for Partially Drained Penetration

This project aims to improve the way in which we store mining waste through furthering the research of the Cone Penetration Testing (CPT) method

The goals of this project are to:

• Developing a coupled cone penetration testing (CPT) model in the commercial software ABAQUS
• Validating the results of the model against available experimental data
• Performing parametric studies to understand various influences on CPT response
• Developing a new interpretation method

The details

Tailings storage facilities (TSF) are man-made structures for storing mining waste, comprised of fine minerals and water left behind during the extraction process. TSFs exist at the intersection of economics, safety, and sustainability.

Tailling, as a typical granular soil, can lose all or part of their strength in a process called liquefaction, where material that is ordinarily a solid behaves like a liquid, much like quick sand.  Soils’ resistance to liquefaction mainly depends on how densely-packed their particles are.

Recently, liquefaction-induced catastrophic failures of TSFs have highlighted a need for improved engineering practices for assessing and improving existing TSFs, designing new TSFs and disposal processes.

The mining industry is also experiencing economic challenges that require reductions in tailings disposal costs and evolving regulatory and social pressures to improve the safety and sustainability of tailings storage. Therefore, the assessment of the safety of TSF is required for the industry practices.

Liquefaction potential is assessed by estimating soil density from its resistance to a penetrating probe. The Cone Penetration Test (CPT) is the predominant site characterization tool since it provides a wealth of information with fast and inexpensive application.
In CPT, a cone shape of penetrometer is pushed into soil at a constant rate. During the penetration, the resistance on the cone can be measured, which can be used to estimate the soil density. CPT is simple and fast to conduct in the field, so it is widely used in engineering practice for in-situ tests.

The cone penetration process has a complicated interaction with the pore water (free water present in soil) in often silt-rich tailings. This is because the  generation of excess pore water pressures (due to the compression of the soil during the penetration process) and the rate of dissipation of the pressure away from the cone. These factors make interpretation of CPT results particularly challenging.

This joint research topic focuses on producing tailings-specific CPT interpretation methods by accounting for the complicated nature of soil, and interaction of soil, water and the advancing cone.

Graduate researcher profile: Xingyu Wu

What did you do before you started your PhD?

Before I start my Ph.D. I received my Master’s degree in Geotechnical Engineering at the University of Ottawa in June 2021.
My Master’s research focused on the numerical modeling of the pile foundation in unsaturated expansive soils.

What are the challenges of your research role?

The biggest challenge is the difficulty in communication. Because of the different languages and cultures, I may face trouble in communication with professors, other colleagues? and friends, which may affect the progress of the research.

What is the best part of your research role?

The best part of my research role is that I have the chance to work in two best universities in the world, the University of Toronto and the University of Melbourne. Because of this opportunity I am able to work with three great professors, meet with more people in different countries, and get more ideas. Getting more experience is the best part of my research role.

Where do you wish to go after your PhD? Do you want to enter industry or continue doing more research?

The first choice for me is to continue my research. Being able to find a position in a university would be ideal, but I also would like to enter industry to get more practice experience.

Supervision team

The University of Melbourne: Dr Shiao Huey Chow, A/Prof Yinghui Tian

The University of Toronto: A/Prof Mason Ghafghazi