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Module

CEG8212 : Assessment of slope stability; design of slopes, mine pitwalls and tailing dams

  • Offered for Year: 2022/23
  • Module Leader(s): Professor Stefano Utili
  • Lecturer: Dr David Milledge
  • Owning School: Engineering
  • Teaching Location: Newcastle City Campus
Semesters
Semester 1 Credit Value: 20
ECTS Credits: 10.0

Aims

1. to introduce students to the design and assessment of slopes, open pit mine pitwalls, excavations and tailing dams according to the current international standards (Eurocode 7 and ICOLD Bulletins).
2. to introduce the theoretical concepts and engineering principles underpinning the assessment of the stability of slopes in rocks and soils.
3. to introduce the students to the use of stability charts, limit equilibrium methods and finite element analyses with shear strength reduction for the assessment of the stability of slopes.
4. to introduce the students to a rational approach for the cost-effective design of cuttings and open pit mine pitwalls.

Outline Of Syllabus

* lectures, tutorials and set problems on the analytical and numerical methods available to carry out slope stability assessment with particular emphasis on Limit Equilibrium Methods and Finite Element analyses
* lectures and tutorials on the use of Eurocode 7 for slope stability assessment and design
* lectures and tutorials on the use of stability charts to assess the stability of slopes in rocks and cohesive soils
* lectures on how to design open pit mines pitwalls with tutorials based on stratigraphies from real open pit mines
* lectures on the typical failure modes taking place in tailing dams and soil liquefiability

The course will teach students how to assess the safety of any type of slope and unsupported excavation in soils and rocks alike in compliance with Eurocode 7 via the use of stability charts, analytical and numerical methods. The main type of failure mechanisms responsible for slope instabilities will be considered including the onset of tension cracks and seismic action. With regard to methods, special emphasis is placed on wedge analysis, Limit Equilibrium Methods and the finite element method with strength reduction technique. The theoretical concepts will be applied to several example cases during tutorials which will offer plenty of timely opportunities to clarify any question. The main principles underpinning the safe and economic design of slopes and mine pitwalls are also taught in the module. A full day is spent to do a computer exercise involving the use of numerical programs of Rocscience which is a commercial state of the art software for slope stability assessment.

2. to introduce the theoretical concepts and engineering principles underpinning the assessment of the stability of slopes in rocks and soils
Slope stability analysis: introduction
Main failure mechanisms: translational, rotational and compound failure mechanisms
Analysis of slope stability under the assumption of infinite slope
The effect of tension cracks on the stability of slopes
Analysis of slopes under seismic action and Newmark’s method
The effect of various hydraulic conditions on slope stability.
Simple Limit Equilibrium Methods (Fellenius and Bishop simplified) for rotational mechanisms
General Limit equilibrium methods (emphasis on Morgensten-Price and Janbu methods)
Tutorials and exercises on carrying out LEM analyses according to Eurocode 7 using the correct partial safety factors.
Finite Element Analysis with shear strength reduction technique of a slope.
Use of Rocscience Slide 2 for deterministic slope stability analysis. Consideration of various scenarios of tension cracks
Use of Rocscience R2 for deterministic slope stability analysis.
Elements of probabilistic slope stability analysis

Hazard assessment and slope stabilisation for cuttings along a road (or network)

Design of open pit mine pitwalls: use of stability charts for Mohr-Coulomb and Hoek-Brown geomaterials. Methods for the conversion of Howk-Brown parameters into Mohr-Coulomb ones for slope stability assessment. Use of Rocscience Slide 2 for the design and assessment of open pit mine pitwalls.
Principles of cost-benefit analyses for the design of road cuttings.
Pros & cons of slope stability assessment by FEM analyses versus LEM analyses

Tailing dams, their modes of failure
Liquefaction of soils
Measurement of soil liquefiability
Measurements of tailing properties by CPT, SPT tests, piezometers etc.
Principles for the risk assessment of tailing dams

Teaching Methods

Teaching Activities
Category Activity Number Length Student Hours Comment
Structured Guided LearningLecture materials600:3030:00non synchronous online lectures providing theory and notions
Guided Independent StudyAssessment preparation and completion180:0080:00Individual Coursework
Guided Independent StudyDirected research and reading110:0010:00Background reading of course texts
Guided Independent StudyDirected research and reading130:0030:00Studying online resources that accompany taught sessions and reading lecture notes
Scheduled Learning And Teaching ActivitiesSmall group teaching131:0013:00Tutorials PiP
Scheduled Learning And Teaching ActivitiesSmall group teaching81:008:00PiP Problem solving Exercises
Guided Independent StudySkills practice12:002:00Practice of practical skills
Scheduled Learning And Teaching ActivitiesWorkshops17:007:00PiP computer exercise using state-of-the art industry software for slope stability assessment
Scheduled Learning And Teaching ActivitiesDrop-in/surgery62:0012:00PiP sessions to answer student queries on development of the coursework
Guided Independent StudyIndependent study18:008:00Practice of tutorial questions
Total200:00
Teaching Rationale And Relationship

The module is taught as an intensive block in order to provide an immersive learning experience with a flexible integration of lectures, tutorials and problem solving sessions.
The module includes lectures to explain the theory, small group teaching activities in the form of tutorials and set problems to be solved to teach the practical application of the theory for slope stability assessment and the design of open pit mine pitwalls and excavations. A computer exercise employing state of the art commercial software is included to teach students how to use industry standard software for slope stability assessment and design.
Drop in surgeries are offered to support the students in the preparation of the coursework assignment (module assessment is 100% based on the coursework).
Plan B for PiP sessions in case of lockdown / severe restrictions: the plan is to run the sessions as synchronous online.

Assessment Methods

The format of resits will be determined by the Board of Examiners

Other Assessment
Description Semester When Set Percentage Comment
Written exercise1M100Individual Report (50 pages)
Assessment Rationale And Relationship

Each student will undertake an individual coursework comprising 1. The assessment of the stability of a slope subject to static and earthquake action and tension cracks by hand calculation and using the Limit Equilibrium Method in accordance with EC7 and pre-Eurocode (global Factor of Safety) legacy standards; 2. The design of the pitwalls of an open pit mine for a prescribed Factor of Safety.

Reading Lists

Timetable