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Research_

Geoenvironmental engineering

Cutting-edge research in geoenvironmental engineering
Experimental, theoretical and computational research at the interface between environmental engineering, geomechanics and soil science.

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:

Our research

University academics: Professor Abbas El-Zein, Professor David Airey, Associate Professor Gwénaëlle Proust, Associate Professor Daniel Dias-Da-Costa, Associate Professor Yixiang Gan

External collaborators: Dr Golnaz Alipour Esgandani, Dr Bowei Yu

PhD students: Sepideh Taheri, Shunzhi Shen, Yifei Gao

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. The group has been conducting theoretical, experimental and computational investigations to develop a better understanding of processes and the capacity to predict them.

University academic: Professor Abbas El-Zein

External collaborators: Professor Abdelmalek Bouazza (Monash University, Australia), Associate Professor Will Gates (Deakin University, Australia), Professor R Kerry Rowe (Queen’s University, Canada)

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. The goal of the project is to develop empirically based and scientifically sound guidelines for the management of PFAS in surface sources.

University academics: Professor Abbas El-Zein, Professor David Airey, Dr Elizabeth Carter, Professor Peter Lay

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. The project conducts a set of experimental investigations to better understand the effect of exposure of bentonite to MP and NP on its microstructural and macroscopic properties.

University academics: Dr Guien Miao, Professor Abbas El-Zein, Associate Professor Thomas Hubble

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. The project investigates the use of native plants in Australia to provide soil reinforcement, aiming to develop design guidelines for their use in geotechnical engineering.

University academic: Professor Abbas El-Zein

PhD students: Steven Ding, 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. The 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. The goal of the project is to develop accurate and cost-effective prediction tools for use by engineers, alongside experimental measurements.