ICGCM Papers:
Roof and Rib Control Strategies
 
 
An Assessment of Coal Pillar System Stability Criteria Based on a Mechanistic Evaluation of the Interaction Between Coal Pillars and the Overburden
35th International Conference on Ground Control in Mining
An Assessment of Coal Pillar System Stability Criteria Based on a Mechanistic Evaluation of the Interaction Between Coal Pillars and the Overburden
by
Guy ReedKent MctyerRussell Frith, Mine Advice Pty Ltd, Newcastle, Australia
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[Conference] 35th International Conference on Ground Control in Mining
[Price] Free  [Comments] 0
[Topical Area] Roof and Rib Control Strategies
[Author] Guy ReedKent MctyerRussell Frith, Mine Advice Pty Ltd, Newcastle, Australia
[Abstract] 
Key Conclusions:
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The PEAK Resin Bolting System (the PEAK System) is a joint initiative between DSI and Mine Advice and is a first attempt to address and alleviate all of the various problem areas within the current ‘industry standard’ resin bolting systems. The considerable laboratory and field based testing undertaken by DSI and Mine Advice has demonstrated that resin bolting system design is an often frustrating compromise, as many of the problem areas are linked by common controls, the improvement of one resulting in a worsening of another. This has resulted in the development of a unique bolting system that is a significant departure from the current industry standard, which has resulted in much discussion and associated disagreement amongst the local peer group.
Key Findings:
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Whilst this set of circumstances has not resulted in large numbers of major strata collapses, adequate strata control is often only achieved at significant cost and vigilance via the rigorous yet onerous strata management processes employed by most Australian collieries. When the link between strata support and both roadway development rates and mining costs are considered, a solution to this set of circumstances is demonstrably necessary and of significant potential value.
Objective of the Paper:
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Discuss Peak Bolting System
Problem Statement:
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Over the past 30 to 40 years, rock bolts used by the Australian underground coal industry have evolved from rudimentary mechanical shell anchors to pre-tensioned resin rebar systems incorporating full encapsulation, the use of two-speed resin cartridges in the order of 1000 to 1400 mm long with high durability Mylar films, catalyst to mastic ratios in the order of 15:1 and various “high ribbed” deformed bar profiles installed in bolt hole diameters as small as 27 mm. This evolution has been largely driven by a desire to maximise load transfer along the full bolt length. However, both historical and more recent research (from both Australia and the US) demonstrate that this combination of bolting consumables and the advent of modern powerful bolting rigs is almost certainly resulting in bolt installations that are not as effective as they could be, or as we think they are. Furthermore, strata damage initiated during bolt installation as a direct consequence of large quantities of resin, small bolt annuli, high ribbed and positive rake deformation profiles and rapid insertion rates are now known to directly impact upon roof stability thus making the achievement of adequate strata stability more difficult and therefore less efficient than it otherwise should be.