Empirical Performance Chart for Ground Support in Seismic Conditions at Mt Charlotte

Mikula, Peter; Lee, Maxwell

doi:10.36487/acg_repo/711_24

Cited by 7 publications

(9 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The compilation of support performance charts relating event magnitude, ground support systems, and extent of damage has been explored for several Western Australian hard rock mines by Mikula and Lee (2007), and Mikula (2012). This work has also been presented at industry workshops (Mikula 2009(Mikula , 2011.…”

Section: Empirical Approach -Support Performance Chartsmentioning

confidence: 99%

See 1 more Smart Citation

Empirical selection of ground support for dynamic conditions using charting of support performance at Hamlet mine

Mikula¹,

Gebremedhin²

2017

Proceedings of the International Conference on Deep and High Stress Mining

Self Cite

View full text Add to dashboard Cite

This paper demonstrates assessment of ground support dynamic performance, using charting of easily available mine site data, to provide guidance for support selection for dynamic conditions. The process is transparent and accessible to site engineers, and is described for the Hamlet gold mine in Australia. The process defines the relationships between three factors: the seismic event magnitude, the level of damage caused, and the installed ground support. The process is firmly based on the recorded history of these three factors at the mine. Site geotechnical engineers need a simple yet defensible support selection method for seismic conditions that can be used with confidence. The aim is to enable selection of the appropriate ground support according to the expected or forecast level of seismic hazard. Empirical charting represents one way of bracketing the performance of particular ground support schemes in dynamic conditions. It assesses the past performance of the installed ground support, to provide guidelines for forward selection of support. This approach has limitations and uncertainties which add to the scatter of the data points in the charts. However, the approach has the advantages of including the actual installed bolts, seismic events, site geology and support performance, making the results calibrated to, and applicable to, the mine. It also benefits by not requiring estimation of quantities, including the ground motion (peak particle velocity) at the location of a support element, the site effect, and the energy and load capacities of those elements during dynamic disturbances. The empirical charts are not transferable between mine sites. It is hoped that the description of the methodology in this paper will encourage engineers to explore similar work for their sites, and gain better understanding of the in situ performance of their ground support under dynamic conditions.

show abstract

Section: Empirical Approach -Support Performance Chartsmentioning

confidence: 99%

“…There is then no need to estimate a site effect factor. This was the approach adopted in previous work by Mikula and Lee (2007), and Mikula (2012).…”

Section: Bypassing the Estimation Of A Site Effect Factormentioning

confidence: 99%

Empirical selection of ground support for dynamic conditions using charting of support performance at Hamlet mine

Mikula¹,

Gebremedhin²

2017

Proceedings of the International Conference on Deep and High Stress Mining

Self Cite

View full text Add to dashboard Cite

show abstract

“…Kaiser et al (1996) present the view that those ejection velocities greater than the PPV are likely to occur for only small ejected blocks, but concede that the ejection velocity could be higher due to stored strain energy around the opening also being transferred to the ejected rock. Mikula and Lee (2007) state that joints are energy sinks and that they slide, grind and absorb incoming dynamic energy; the addition of ground support increases the ability of a jointed rock mass to absorb energy and this could reduce the likelihood of ejection. This further complicates the estimation of ejection PPV.…”

Section: Estimating Energy Absorption (E a ) Demandmentioning

confidence: 99%

Dynamic ground support — design methodologies and uncertainties

Dunn¹

2017

Proceedings of the International Conference on Deep and High Stress Mining

View full text Add to dashboard Cite

The design of ground support needs to account for a number of uncertainties relating to loading conditions, rock mass variability, rock mass response and ground support performance. When designing ground support for dynamic conditions, the uncertainties are magnified due to significant gaps in our understanding of how the rock mass responds to dynamic loading as well as limitations in available design methodologies (conceptual uncertainty). In reality, the fundamentals of dynamic ground support design have changed little over the last three decades and there are many assumptions and limitations. This paper will discuss some of these limitations, as well as highlight how uncertainty around significant parameters, such as peak particle velocity and design magnitude, impact on the design. Comparisons will be made on how dynamic ground support design is approached in Australia and South Africa. A case study that demonstrates both our general lack of understanding and how variable the rock mass loading and response can be over a short distance will be presented. Suggestions will be made on how to address some of the shortcomings and uncertainties in the design of ground support for dynamic conditions.

show abstract

“…As part of this project, an empirical design chart for dynamic support was developed (Mikula and Lee, 2007) to ensure ground support would be adequate for the expected seismicity.…”

Section: Ground Supportmentioning

confidence: 99%

Destressing the ROB5 Remnant Using Tight Slot Blasting at Mt Charlotte Mine

Kempin¹,

Sprague²,

Narendranathan³

et al. 2007

Proceedings of the International Conference on Deep and High Stress Mining

Self Cite

View full text Add to dashboard Cite

The Mt Charlotte ROB5 orebody remnant had defeated two earlier attempts at stoping, with Richter magnitude (M R ) 2.2 to 2.9 seismic events in 1995 and 1997 causing a halt to production.A destressing strategy, known as Tight Slot Blasting (TSB), was subsequently developed for this orebody. It was designed to manage fault-slip seismicity on several major structures intersecting the ROB5 area. The objective was to destress by creating a slot 150 m long and up to 40 m high along the entire western edge of the orebody. The concept was validated using a calibrated numerical modelling study, and the key elements involved tight firing (low blast expansion void) and rapid firing (electronic detonation).Mining commenced in August 2006. At that time, four particular R-shears (sub-vertical and striking NE-SW) were identified as requiring specific seismic management. A blasting schedule was defined using four TSB segments to advance the slot across these structures. To date, two TSBs have been conducted and 80% of the orebody has been destressed, but practical blasting issues have affected the project, and fault-slip seismicity has also been experienced.Bridging of intact rock across the slot has been a major problem, and methods of dealing with this have been developed. The main issue was long up-holes that toed into highly stressed, fractured and open ground below the previous ROB5 undercut.The largest fault-slip event, M R +2.2, was the same as the project maximum that was estimated in 2004. Ground support has generally performed well. The TSB strategy has provided the required control of event magnitude, but not event timing. This is a significant project. It has added 18 months to the life of the mine, and represents a rare attempt to achieve stope-scale destressing in the face of fault-slip seismicity.

show abstract

Empirical Performance Chart for Ground Support in Seismic Conditions at Mt Charlotte

Cited by 7 publications

References 5 publications

Empirical selection of ground support for dynamic conditions using charting of support performance at Hamlet mine

Empirical selection of ground support for dynamic conditions using charting of support performance at Hamlet mine

Dynamic ground support — design methodologies and uncertainties

Destressing the ROB5 Remnant Using Tight Slot Blasting at Mt Charlotte Mine

Contact Info

Product

Resources

About