Geoenvironmental engineering
The Geoenvironmental Engineering Group leads valuable research in geoenvironmental engineering.
Research topics include:
- subsurface contamination by organic and inorganic compounds,
- experimental, theoretical and numerical study of soil under wet-dry and thermal cycles,
- self-repair in clay soils and the behaviour of polymer-enhanced clay, and
- modelling of urban flooding under climate change.
Our work is funded by Australian Research Council (ARC) Discovery and Linkage grants as well as University of Sydney PhD scholarships.
Our experimental investigations are conducted in our Geoenvironmental Laboratory (GEL), Soil Mechanics Laboratory, Environmental Laboratory as well as central Sydney Analytical laboratories.
Recent achievements:
- Two new ARC Discovery successes: a multi-University team, led by Professor Abbas El-Zein, has been awarded funding over the 4 years (2022-2026) to the total value of A$550k by the Australian Research Council, to carry out an extensive investigation into the ability of clay liners to protect groundwater from microplastics and nanoplastics. Another grant of A$250k was awarded to a project led by Professor David Airey, in collaboration with the University of Adelaide, to study the pile foundations of energy farms and the risk associated with cracking and desiccation. A core of the experimental and numerical investigations in these two projects will be conducted at the Soil Mechanics Laboratory, Geoenvironmental Laboratory and Sydney Analytical
- First-time observation of self-repair of cracks in bentonite clay in real-time using x-ray computed tomography under controlled initial conditions (MPhil graduate: Yifei Gao, 2021).
- A new, experimentally validated, thermodynamically consistent formulation for the modelling of hydro-mechanical behaviour of self-repairing soils (Post-doctoral fellow: Dr Golnaz Alipour Esgandani, 2020).
Our research
Our experts: Professor David Airey, Professor Abbas El-Zein, Professor Gwénaëlle Proust, Associate Professor Daniel Dias-Da-Costa, Associate Professor Yixiang Gan, Dr Bowei Yu
Our partners: Dr Golnaz Alipour Esgandani (Macquarie University, Australia)
PhD students: Yifei Gao, Shunzhi Shen, Sepideh Taheri
Clay in several geoenvironmental and geotechnical engineering applications undergoes cycles of wetting and drying. This can lead to desiccation cracking, loss of key properties and an increased risk of failure in slopes, pavements, foundations and waste-barrier lining systems.
Desiccation cracking has been studied extensively over the last few decades. Far less understood is the capacity of clay to autogenously close its cracks and recover some mechanical, hydrological and thermal properties upon rehydration.
We're conducting theoretical, experimental and computational investigations to develop a better understanding of processes and the capacity to predict them.
Our expert: Professor Abbas El-Zein
Our partners: Professor Abdelmalek Bouazza (Monash University, Australia), Professor R Kerry Rowe (Queen’s University, Canada), Associate Professor Will Gates (Deakin University, Australia)
PhD student: Linxue Zhao
Per and poly-fluoro alkyl substances (PFAS) are persistent organic contaminants that, until recently, have been found in a range of products, including packaging material, fire-fighting foams and cosmetics.
Human exposure to PFAS has been linked to a host of health conditions, including liver and testicular cancer, increased blood pressure in pregnant women and high blood cholesterol. Protection of groundwater from PFAS present in polluted sites and municipal waste landfills around the world is hence an important endeavour for scientists, engineers and regulators.
Management of surface sources of PFAS is made difficult by significant uncertainties and knowledge gaps about their interactions with the soil material that separate them from an aquifer in both engineered barrier systems and non-engineered disposal environments.
The investigation, part of a wider ARC linkage project, builds and validates new probabilistic models to predict PFAS transport in soil and groundwater. Our goal is to develop empirically based and scientifically sound guidelines for the management of PFAS in surface sources.
Our experts: Professor Abbas El-Zein, Professor Peter Lay, Dr Elizabeth Carter
Our partners: Professor Abdelmalek Bouazza (Monash University, Australia), Professor R Kerry Rowe (Queen’s University, Canada), Associate Professor Will Gates (Deakin University, Australia)
PhD student: Yifei Gao
Microplastics (MP) and nanoplastics (NP) have been detected in a wide range of physical and biological systems and associated with a host of health conditions. Prevention of their proliferation is hence one of the most urgent environmental challenges of the 21st century.
Bentonite clay is found widely in waste-containment barrier systems around the world as a key insulation material to prevent organic and inorganic contamination of groundwater. On the other hand, little is known about the effects of MP and NP on the insulation properties of bentonite clay.
We're conducting a set of experimental investigations to better understand the effect of exposure of bentonite to MP and NP on its microstructural and macroscopic properties.
Our experts: Professor Abbas El-Zein, Associate Professor Thomas Hubble, Dr Guien Miao,
PhD student: Joey Zhu
Landslides cause significant human suffering and economic damage around the world. Slope stability is affected by natural topological factors, wet-dry cycles, soil properties as well as human interventions.
Conventional geotechnical approaches to soil reinforcement vary in their effectiveness and are often costly to implement. On the other hand, the roots of plants and trees are known to provide additional cohesion to soils. However, knowledge gaps persist in our understanding of the reinforcement mechanisms triggered by roots in soils and prevent a wider adoption of this approach.
Our project investigates the use of native plants in Australia to provide soil reinforcement, aiming to develop design guidelines for their use in geotechnical engineering.
Our expert: Professor Abbas El-Zein
PhD students: Steven Ding, Hamed Faizi, Matthew Hanna (undergraduate thesis student)
The ability to predict chemical, thermal and hydro-mechanical behaviour of soils under various environmental conditions is critical for achieving desirable environmental and engineering objectives.
This project applies state-of-art artificial intelligence, including neural networks and other nature-based algorithms, to develop new tools for predicting soil behaviour and properties.
Of particular interest is the behaviour of clayey materials, including geosynthetics clay liners (GCLs) widely used in geoenvironmental engineering applications around the world. Our goal is to develop accurate and cost-effective prediction tools for use by engineers, alongside experimental measurements.
Our expert: Professor David Airey, Professor Abbas El-Zein
PhD students: Hamed Faizi, Shunzhi Shen, Sepideh Taheri
We're investigating the ability of amendments such as polymers or fly ash to achieve specific engineering properties of clayey soils, including their compressive and tensile strengths, swelling and shrinkage potential as well as resistance to acidic water.
Experimental, theoretical, and computational developments are conducted towards a decision-making framework for material selection and process design.