Geomechanics of Mine Waste Management

Over more than 30 years, Professor David Williams has been at the forefront of the application of geotechnical engineering principles to mine waste management, mine design, mineral processing, and mine closure.

Our Projects

High stress consolidometer
High stress consolidometer
Sampling mine spoil
Sampling mine spoil
Instrumenting mine tailings
Instrumenting mine tailings
Laboratory tailings column
Laboratory tailings column

Geomaterial Modelling and Computational Geomechanics

Geomaterials are a highly complex mixture of solid particles, pore water and pore air, requiring the development of innovative, complex mathematics and algorithms, and the use of parallel computing, which the Centre developed.

In addition to conventional methods (e.g. finite element methods, FEM), the Centre extends and develops new methods for the prediction of the mechanical behaviour of (porous) solids and granular materials, including (where desired) multi-component fluid flow. Continuum and discrete approaches are both considered.

Our Projects

Dr Dorival Pedroso, and his co-workers, developed the computer software MechSys (Open Library for Mechanical Systems), which serves as a basis for the development of the models and solvers. MechSys includes FEM, and in collaboration with Dr Sergio Galindo-Torres has added the discrete element method (DEM), smoothed-particle hydrodynamics (SPH), and the lattice Boltzmann method (LBM). MechSys is under constant development.

Another focus is engineering optimisation, in particular employing advanced new optimisation techniques such as Genetic Algorithms. For this, the computer library SGA (Simple Genetic Algorithms) serves as a basis for the development of optimisation tools. Accuracy and reliability are of key importance.

MechSys/LBM modelling of flow through porous media
MechSys/LBM modelling of flow through porous media
MechSys/LBM modelling of flow through porous media
MechSys/LBM modelling of flow through porous media

MechSys/LBM modelling of flow through porous media

MechSys/LBM simulation of viscous fluid flow under gravity around an obstacle
MechSys/LBM simulation of viscous fluid flow under gravity around an obstacle
MechSys/LBM simulation of viscous fluid flow under gravity around an obstacle
MechSys/LBM simulation of viscous fluid flow under gravity around an obstacle

MechSys/LBM simulation of viscous fluid flow under gravity around an obstacle

MechSys/LBM simulation of multi-component flow – a bubble (shown in blue) expands, moves to the surface, then breaks the surface, while the liquid (shown in red) settles
MechSys/LBM simulation of multi-component flow – a bubble (shown in blue) expands, moves to the surface, then breaks the surface, while the liquid (shown in red) settles
MechSys/LBM simulation of multi-component flow – a bubble (shown in blue) expands, moves to the surface, then breaks the surface, while the liquid (shown in red) settles
MechSys/LBM simulation of multi-component flow – a bubble (shown in blue) expands, moves to the surface, then breaks the surface, while the liquid (shown in red) settles

MechSys/LBM simulation of multi-component flow – a bubble (shown in blue) expands, moves to the surface, then breaks the surface, while the liquid (shown in red) settles

Advanced Laboratory and Field Characterisation

The advanced laboratory and field characterisation and testing, modelling, and monitoring of slurries, soils and rocks has been a focus of the Centre’s research, involving many of its researchers.

Laboratory testing has included the sedimentation testing of tailings slurries, the consolidation testing of soft soils and tailings through to coal mine spoil under stresses of up to 10 MPa, the shear strength testing of soft soils and tailings through to coal mine spoil, and the soil water characteristic and saturated hydraulic conductivity testing of soils and spoil. Soil and tailings slurries have been subjected to laboratory modelling to determine their beaching behaviour and their consolidation under load.

Our Projects

Laboratory testing projects have included desiccation of clay liners, column testing of mine tailings, filtration testing of tailings, and the application of an ultra-high speed camera to capturing rock fracture.

Field testing and monitoring has included the instrumentation of tailings and mine waste covers, pile load testing, the application of ground penetrating radar, and hydraulic conductivity and density testing of fine and coarse-grained mine wastes.

Ultra-high speed camera for capturing rock fracture
Ultra-high speed camera for capturing rock fracture

(above) Ultra-high speed camera for capturing rock fracture

Ground penetrating radar testing
Ground penetrating radar testing

(above) Ground penetrating radar testing of mine haul roads

Geo-environmental Engineering and Geophysical Methods

Dr Alexander Scheuermann is an expert in dam engineering, geo-environmental engineering and flood protection.

Spatial TDR cable
Spatial TDR cable

He has also researched the hydraulics and mechanics of unsaturated soils. His research activities include hydro-mechanically coupled processes such as erosion, shrinkage of soils, stability of partly-saturated soils and hydraulic fracturing; and transient seepage, infiltration of water, soil water retention curve and preferential flow of water. To investigate these processes, he uses geophysical methods such as Time Domain Reflectometry (TDR), Electrical Resistivity Tomography, Ground Penetrating Radar and Dielectric Spectroscopy.

For almost 15 years, Alexander has been working on the development, modification and application of spatial TDR for observing geo-environmental and geotechnical processes and co-developed a method called Spatial TDR. The advantage of Spatial TDR compared to conventional TDR methods is its ability to determine profiles of desired parameters such as the volumetric water content. Applications of this novel technology include the observation of water content changes within embankments, in small catchments for improving flood forecasting or in mine waste cover systems. Further applications include the determination of soil water characteristics, the measurement of porosity changes during erosion, and potentially fluidisation and the measurement of stress changes.

Management of Large Open Pit Project (LOP II)

Professor David Williams, assisted by Dr Mehdi Serati, manages the industry-funded Large Open Pit Project (LOP II, 2016-2019), a continuation of LOP I (2004-2015), and is managing the funding of LOP III (2019-2022).

The focus of LOP I was the development and publication of a number of guidelines including Guidelines for Open Pit Slope Design (Read and Stacey, 2007), Guidelines for Evaluating Water in Pit Slope Stability (Beal and Read, 2013), and the soon to be published Open Pit Dewatering, Guidelines for the Design of Slopes in Weak Rock, and Guidelines for the Design of Mine waste Dumps and Stockpiles. LOP II will continue the tradition of setting standards for the industry and improving on the state-of-the-art through targeted research with short-term deliverables.

The focus of LOP II is data and design uncertainty, accounting for blast-induced rock damage, drafting Guidelines for Slope Monitoring, laser scanning and structural modelling, updating design acceptance criteria, developing an LOP Website (www.lopproject.com), and effective stresses in large open pit slopes.

Themes for LOP III – Open Pit of the Future include automation of mining and its implications for the factor of safety and the resource; data acquisition and visualisation; data management and analytics; open pit closure, including in-pit tailings and pit lakes; monitoring, risk management and artificial intelligence; staffing and capability; mining methods; mine void design; dynamic slope stability; implications of deeper open pits; and interaction and transition between ongoing open pit and underground.

Current and Recent Projects

GEC Researchers Take on Ever-increasing Waste Glass and Overexploitation of Natural Sand

Description of the Video Abstract:

The video abstract features Danish Kazmi, a PhD candidate in the GEC, and his PhD advisors Professor David Williams and Dr Mehdi Serati. It presents the key motivations, analyses performed, and conclusions of cross-institutional research published recently in the Journal of Cleaner Production, a Q1 journal ranked number# 1 worldwide in Sustainable Development at the time of this article publication.

Performed in collaboration with University College London (UK) and other external organisations, this research investigated the potential use of ever-increasing waste glass as a sustainable alternative to depleting natural and manufactured sand in geotechnical construction. The study compared the geotechnical, mineralogical and morphological behaviour of crushed waste glass with that of two traditional types of construction sand. The findings showed that the geotechnical behaviour of crushed waste glass is similar, or sometimes even superior, to traditional construction sands. Overall, it was concluded that crushed waste glass could potentially serve as an alternative and smart geomaterial, ultimately promoting the recycling of waste glass, reducing the burden on landfill and conserving natural resources, all helping the transition towards a circular economy.

Article title: The potential use of crushed waste glass as a sustainable alternative to natural and manufactured sand in geotechnical applications.

Article DOI: https://doi.org/10.1016/j.jclepro.2020.124762