Improving Reliability of Structural Domaining for Engineering Projects

Carter, Trevor G.; Barnett, Wayne

doi:10.1007/s00603-021-02544-6

Cited by 4 publications

(2 citation statements)

References 25 publications

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“…Then, if appropriate, numerically model those specific mechanisms in an attempt to quantify the FoS. This idea is not new per se; Carter (2015) and Carter & Barnett (2021) have produced several papers stressing this point. By no means would this approach ensure all potential instabilities are identified at the design stage, but it would make designs more defensible.…”

Section: Conclusion and Considerations For The Industrymentioning

confidence: 99%

Safe management and optimisation of deforming pit walls

Abrahams

2023

SSIM 2023: Third International Slope Stability in Mining Conference

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Deforming pit walls are not uncommon in surface mining, primarily due to the complexity and unpredictability of ground conditions. Indeed, slope deformation beyond original design expectations should not always be considered unacceptable because, if managed safely and proactively, the mining operation can continue to optimise its planned ore recovery.Due to the significant advances in slope monitoring technologies over the last 15 years, safe management of slope deformation is now very achievable with a high degree of confidence provided that monitoring and reconciliation approaches are best practice. Furthermore, the author argues that early detection of slope deformation should also be industry standard since this allows the economic risk of any slope instability or complete failure to be assessed and then managed more optimally.Analysis of observed slope performance provides detailed information and verification on actual geological and structural conditions, slope behaviour in response to mining, and identification of the actual failure mechanism/s. Such information cannot be expected to be available at such a high level of confidence during the initial design stage.A detailed back-analysis of an area of deformation, obtained by both sub-surface and surface monitoring, will enable the different remediation options to be assessed. This may include continuing to mine the existing designed slope, but with Factor of Safety (FoS) below the original design acceptance criteria (DAC) and, in some cases with an FoS ≈ 1, if slope behaviour is considered to deform gradually rather than collapse catastrophically and all safety aspects are fully managed.Review of high precision slope performance data for a historic slope should be a critical part of future slope designs to enable fully optimised slope designs. This may even enable the option to consider relaxing the DAC when the potential failure mechanism is much better understood. This paper reviews case studies of slope deformations with very different behaviours and economic risks, and shares learnings to provide guidance on managing both the safety and economic aspects of pit wall instabilities. A proposed process flow is provided for how slope deformations should be assessed, risks identified, managed and incorporated into future slope designs and mine plans.

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Section: Conclusion and Considerations For The Industrymentioning

confidence: 99%

Safe management and optimisation of deforming pit walls

Abrahams

2023

SSIM 2023: Third International Slope Stability in Mining Conference

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“…Guidelines for differentiating between natural geological variability and uncertainties due to data inadequacy related to level of required understanding by project stage are outlined in Carter & Barnett (2021) based on assessment of domain modelling reliability, which ideally will increase to the right in the graphs in Figure 6.…”

Section: Design Service Lifementioning

confidence: 99%

Transitioning from mine operations to closure: the dilemma of differing geotechnical design acceptance criteria perspectives

Carter¹,

Graaf²,

Dixon³

et al. 2022

Mine Closure 2022: 15th Conference on Mine Closure

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For open pit mining, understanding and managing slope performance is critical for both operations and closure. Towards the end of mine life, achieving reliability of slope performance in operations often necessitates real-time implementation of active slope stabilisation controls. This situation changes significantly towards closure, when production economics are no longer the priority, and resources for field monitoring control and active slope management diminish. The risk profile also shifts to a greater focus on stakeholder needs, including the environment and social acceptance, as land use changes. Although risk profiles will shift, the safety goal of 'zero harm' needs to continue to be achieved through all phases.Historically, most final pit slopes were not designed for closure. Rather, they tended to be optimised for production efficiency and thus were typically too steep for long-term reliability. The key question then becomes -what happens when the controls that have been put in place for maintaining their stability are decommissioned for closure? With sufficient understanding gained during operations, it may be possible to adequately forecast behaviour and define a Design Acceptance Criteria appropriate for the slope, for post-closure, once operational controls are decommissioned. This paper is hoped will help address this dichotomy and provides suggestions to meet industry objectives. It is also intended to promote discussion on this transition, such that industry and regulator perspectives can be accommodated alongside each other within the forthcoming Large Open Pit (LOP) Guidelines for Mine Closure handbook publication, currently in preparation under the auspices of the LOP initiative.

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Rock Mass Classification Systems: A Useful Rock Mechanics Tool, Often Misused

Alejano

2024

Rock Mech Rock Eng

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Rock mass classification systems (RMCS) were developed in the seventies of the last century. They were born in response to the need to establish indicative design criteria for tunnel support. But they also focused on rating the quality of the rock, putting numbers in geology that allowed the rock mass to be classified and its parameters computed. RMCS attempted to consider the most relevant geomechanical aspects affecting the rock mass, including parameters related to rock structure and joint surface conditions. However, to be used as design approaches, they covered parameters not related to the rock mass itself (excavation orientation, stress state…). This multiple focus, together with other intrinsic limitations, has introduced some confusion in its application. A discussion is presented on the application of RMCS to solve rock engineering problems based on the author’s experience, addressing the geological background and their applications. The author reports on some small-scale rock engineering studies including the results of basic RMCS, presenting the potential problems encountered, if any, and the usefulness of the approach in relation to the objectives of the study. While a “design as you go” approach, based on RMCS of the tunnel face combined with observations, measurements and expertise, has often been successful, its direct application for design purposes without further considerations tends to produce problems. Very useful and almost necessary for comparative purposes, these simple approaches may, however, not always produce the right answers to design questions or may lead to wrong decisions if used without additional thoughtful considerations.

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Improving Reliability of Structural Domaining for Engineering Projects

Cited by 4 publications

References 25 publications

Safe management and optimisation of deforming pit walls

Safe management and optimisation of deforming pit walls

Transitioning from mine operations to closure: the dilemma of differing geotechnical design acceptance criteria perspectives

Rock Mass Classification Systems: A Useful Rock Mechanics Tool, Often Misused

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