Course: An Engineering Craft: Stability Modelling of Tailings Storage Facilities

• Course Date: November 14-16, 2022
• Venue: Misty Hills Country Hotel, Conference Centre & Spa, 69 Drift Boulevard, Muldersdrift (Johannesburg) 2198, South Africa.
• Languages: The course will be conducted in English
• Registration Fees:
  • Early Bird - USD $700 (until October 25th, 2022)
  • Regular - USD $900

Offer: Registrants who have Rocscience Maintenance+ plans get a 10% discount on the course fee.

What’s included:

• Temporary software licenses
• PDF of course materials
• PDH certificate (CPD)
• Lunch and refreshments

Please note:

• Registrants will be responsible for their own accommodation
  
• Participants must bring their own laptops (and mice)
• The number of participants will be capped at 25

Course Outline:

Rocscience is pleased to announce a training course in Muldersdrift, South Africa, on applying the company's software suite to modelling and solving tailings dam stability challenges. This three-day training course is designed for all experience levels and will be taught by world-class specialists.

The course aims to facilitate a proactive approach to the stability analysis of tailings storage facilities (TSFs) that better anticipates and mitigates stability risks over their lifespan. It will help professionals to maximize the insights they can glean from incomplete information and improve their understanding of material behaviours and site investigations. The course desires to help the tailings community to recognize any weaknesses in the engineering and performance of TSFs long before these flaws evolve into failures.

The course will provide insights into drained and undrained behaviours of tailings, embankment materials and foundation soils. It will give essential know-how on soil mechanics, tailings properties and behaviour, geotechnical engineering, and impact/ influence of groundwater pressures. It will focus on loose silty sandy tailings and soils and weak slimes (contractive materials) that can liquefy under static and dynamic loads with extreme consequences.

This three-day course will help participants achieve these goals by learning the following state-of-the-art software: Slide2 and RS2 (and introduction to Slide3 and RS3). These programs incorporate current best-practice geotechnical knowledge and modelling technologies to model TSF behaviours and performance. It will review limit equilibrium and finite element advances for modelling TSF behaviours under different loading conditions and at various stages of development.

The course is intended for professionals (Engineers of Record, Owners, Consultants, Regulators, and Responsible Tailings Facility Engineers) who seek to understand tailings dams' stability performance better and broaden their knowledge of recent TSF modelling advancements. Other mine specialists, such as Mill Superintendents and Metallurgical Engineers, who need a basic working knowledge of TSF stability assessment, may also attend.

Objectives

This hands-on training course will help participants with the following:

• Undertake TSF stability analysis to support design, changes during operations and closure
• Appropriately choose analysis tools, loading conditions, material strength and constitutive models
• Close gap in tailings stability analysis skills
• Take real-world problems and break them down into simpler components that are solvable with software tools
• Promote and develop simple, practical, and easy-to-apply modelling approaches

Course Agenda:

Through a mix of presentations and “hands-on” tutorials based on practical TSF embankment examples, the course will cover the following topics:

The Craft of Tailings Engineering – John Wates

• Why TSFs may fail more often than water dams
• The changing nature – and permanence – of TSFs
• The need to predict TSF performance/stability by computation and modelling
• The need for stability analyses and software to support analysis
• Review of recent high-profile TSF failures
• Role of stability analysis in understanding failures

Mechanical Behaviour of Soils and Tailings

• Fundamental characteristics of soil behaviours - shearing responses of granular material (soils and tailings)
  • Volume changes under shearing – dilative and contractive responses to loading
  • Change in stiffness with stress and strain levels
  • Density/void ratio/state
  • Dilatancy (dilation angle)
  • Drained (effective stress) vs undrained (total stress) analyses
  • Brittle vs ductile behaviour
  • Consolidation
  • Post-peak and residual behaviour
  • Critical state/liquefaction
  • Parameters for characterizing the mechanical behaviour of soils and tailings

Constitutive/Material Behaviours of Soils and Tailings

• Constitutive behaviours of soils and tailings
  • Strain hardening
  • Strain softening
  • Peak strength
  • Fully softened strength
  • Post-peak strength
  • Residual drained strength
  • Pre-liquefied strength
  • Post-liquefied strength
• Constitutive material relationships
• Advanced constitutive relationships – critical state soil mechanics
• Modelling of initial states and construction stages of TSFs
• Selection of suitable constitutive models and parameters to simulate expected tailings and soil behaviours

Overview of TSF Stability Analysis and Modelling with Software

• Failure mechanisms of TSFs
  • Slope instability
  • Foundation failure
  • Liquefaction
• Measures of stability
  • Factor of safety
  • Probability of failure
  • Deformations
  • Seepage
• Factors affecting embankment stability – review of inputs required for TSF stability analysis
• Formulating the right problem
• Choosing the right tool
• Benefits and dangers of using software

Overview of Slope Stability Analysis Methods and Software

• Limit equilibrium methods (LEMs)
• Numerical methods
• When do we apply which method
• 2D vs. 3D

Fundamentals of Limit Equilibrium Methods (of Slices)

• Methods of slices (Bishop, GLE/Morgenstern, Janbu, Spencer, etc.)
• Circular and non-circular
• Assumptions of LEM
• Choosing appropriate methods of slices
• Probabilistic analysis

Numerical Methods

• Overview /fundamentals of numerical methods – finite element method (FEM), finite difference method (FDM), boundary element method (BEM), discrete element method (DEM)
• Where to put model boundaries
• Boundary conditions to be applied
• Meshing of models
• Stress deformation analysis
• How stress-deformation analysis (deformations, strains, stress states, pore water pressures, etc.) can be used to assess dam safety and performance

Verification of Models and Model Assumptions

• Capturing of diverse geotechnical and hydrogeological conditions, material behaviours (and associated strength parameters) under various loadings and multiple construction stages
• Judgement of analysis outputs for reasonableness (results that reflect actual performance and reproduce the essential aspects of TSF behaviours

Matching Analysis Methods to Study Levels

• Conceptual design or scoping level
• Pre-feasibility
• Feasibility/ detailed design

Slope Stability Design Criteria

• Acceptable factors of safety
• Design guidelines – (ICOLD, ANCOLD)

Loading Conditions and Associated Drainage Behaviour of Soils and Tailings

• Understanding different drainage conditions – drained, undrained and particularly coupled (consolidation) conditions
• Rapid loading and undrained shearing conditions
• Drained conditions
• Partially drained (transient)
• Peak vs residual strength
• Choice of appropriate material strength models and properties for different drainage and loading conditions
• Matching strength/constitutive models to drained or undrained conditions
• End of construction
• Seismic loading conditions and seismic analysis

Consolidation Analysis using Coupled Hydromechanical Models

• Excess pore pressure - what is excess pore pressure?
• Coupled hydromechanical analysis of TSFs
• Goals of coupled analysis
• Typical outputs
• Static liquefaction modelling
• Liquefaction analysis
• Settlement analysis of TSFs

Seepage and Groundwater Analyses

• Pore pressure changes in TSF embankments, stored tailings, and foundation
• Modelling pore pressures in tailings dams and foundations
  • Steady-state seepage
  • Transient
  • Coupled analyses
  • Excess pore pressure

Introduction to 3D Slope Stability Analysis

• When should we model in 3D? Comparing 2D and 3D slope stability analyses
• Developing 3D geometries and interpreting 3D results

Course Instructors:

Dr. Reginald Hammah, Ph.D., P.Eng., Director, Rocscience Africa

Dr. Reginald Hammah holds a Ph.D. in Civil Engineering from the University of Toronto and brings over 20 years of experience in rock mechanics and geotechnical engineering. He uniquely blends practical problem-solving experience with software tools and theoretical understanding of excavation behavior. He is well known for breaking down complex problems into simpler, more familiar, and solvable components.

Mr. John Wates, B.SC.(Eng.), M.Sc. (Eng.), MBA

John Wates is a geotechnical and tailings consultant with more than 40 years of experience in tailings and industrial waste. After more than 20 years with Golder Associates, he moved to operations with Fraser Alexander, a mining services company that operates more than 100 tailings facilities on behalf of mining companies. Here, John serves as the non-executive chairman.

John has specialized in thickened tailings and paste and has authored several peer-reviewed and conference papers. He is currently involved in the senior review of tailings projects and serves on more than 15 independent tailings review boards across the globe.

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For any additional queries, please reach out to Ruth Obeng-King