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|4 and 6 point timber chock constructions are used extensively on both a systematic and spot basis by Australian longwall operators to support tailgate roadways. In 1996, the School of Mining Engineering at UNSW published design and performance criteria for timber chocks constructed from Australian hardwoods. The research was funded by the Australian Coal Association Research Program (ACARP). In 1997, ACARP awarded funding for a stage 2 testing program. This testing focussed on examining the effect of using thinner timber elements in chock constructions to improve OH&S and comparing the full-scale performance of traditional 4 point chocks to Link-n-Lock constructions. It was established that chocks constructed from thinner elements have failure loads much less than thicker elements. However up to the failure loads of the thinner elements there was no significant difference in the response to convergence of chocks constructed from 25, 50 or 100mm thick elements. Chocks constructed from 150mm thick elements have a similar ultimate strength to the 100mm thick elements. However, they have a significantly lower resistance to load, thereby permitting more convergence to occur. There is more potential for chocks comprised of thin elements to be constructed 'out of plumb' and so suffer eccentric loading. The full scale testing program established that at any given level of convergence up to 10% strain, the timber in a Link-n-Lock chock generates twice the support resistance of the same quantity of the same timber in an equivalent size 4 pointer chock. On the basis of support resistance per cubic metre of timber, there is only a marginal difference in the performance of 1.0m Link-n-Lock chocks and 1.2m Link-n-Lock chocks constructed from select Blue Gum. The cost per tonne of support provided by a Link-n-Lock chock is effectively half of that provided by a 4 pointer chock of equivalent dimension and timber. Up to a strain level of 4%. Link-n-Lock chocks constructed from 1.2m long elements are slightly more cost effective than the same chocks constructed from 1.0m long elements. Thereafter, there is no significant difference in cost per tonne of support resistance. Beyond a strain level of about 4%, Link-n¬Lock chocks constructed from landscape grade Blue Gum are just as cost effective as Link-n-Lock chocks constructed from structural grade 4 Blue Gum.|
Additional chapters/articles from the SME-ICGCM book Proceedings 19th International Conference On Ground Control In Mining
|An Approach To Identifying Geological Properties From Roof B||Field Experience Of Measuring The Acoustic Energy From A Ham||Advancements In Reflective Seismic Tomography For The Locati||Longwall Geomechanics, An Australian Perspective||Moonee Colliery: Renewing The Economic Viability Of A Mine U||Successful Application Of Hydraulic Fracturing To Control Wi||Pillar Mining And Longwalling Below Massive Roof Strata: Geo||High Capacity Tensioned Cable Bolts For Tailgate Support||Single Point And Full Scale Laboratory Testing Of Timber Cho||Optimizing Secondary Roof Support With The NIOSH Support Tec||The Use Of Cribless Tailgates In Longwall Extraction||Five Stress Factors Conducive To Bumps In Utah, USA, Coal Mi||Development Of Stress Measurement Techniques In Bump-Prone C||Coal Mine Seismicity And Bumps: Historical Case Studies And||Multi-Scale Assessment Of Coal And Gas Outbursts Based On Fr||Horizontal Stress: The Root Of All Evil?||Utilizing The ?Advance And Relieve? Method To Reduce Horizon||Regional Horizontal Surface Displacements Due To Mining Bene||Prognosis And Control Of Mining Induced Surface Subsidence A||Prediction Of Subsurface Subsidence For Longwall Mining Oper||Development Of A Statistical Technique For Assessing Sandsto||Evaluation Of Surface Subsidence Potential Along A Pipeline||Roof Monitoring In Limestone Mines-Experience With The Roof||Site Characterization For Planning Underground Stone Mines||Potential Problems Related To Mining Under Or Adjacent To Fl||Mine Planning For Longwall And Pillar Retreat Panels Subject||Optimization Of District-Wide Mine Layout In Multi-Seam Mini||Application Of Bolt Design Criteria At Galatia Mine||The Utilization Of Rockbolting Technology And Monitoring Tec||Rockbolting For Highly Stressed Roadways||Evaluation Of Measurement System For Monitoring The Stabilit||Quality Management For Grouted Rockbolts||Evaluating Anchorage Mechanisms Of Fully Encapsulated Rock B||INSTáL CableOx: A New Tensionable & Corrosion Resistant Cabl||Rock Reinforcement Longevity||Progress In The Development Of A Roof Bolt Design Methodolog||Case Studies Of Progressive Pillar Failure In Two Mines Usin||Jointing Effects On Pillar Strength||Impact Of Vertical Stress On Roadway Conditions At Dartbrook||Stepwise Support Technology For Extremely Soft Rock Roadway||Mobile Roof Supports For Pillar Retreat Mining||Three-Dimensional Simulations Of The Roof Behavior In Coal R||Roof Behavior In South African Coal Room And Pillar Panels||Extended Cut Out Distances In Continuous Miner Sections In S||Roof Control Analysis In North River Mine||Analysis Of The Seam Inclination Effect On Roof Stability||The Application Of Rock Mass Classification Principles To Co||Mining Geotechnical Benchmarking||Using The Point Load Test To Determine The Uniaxial Compress||The Influence Of Water Content On Strength Characteristic Of||Polymer Membrane Liners In Underground Coal Mines - Ground C||Applications Of Cement Grouting Method For Controlling Weak||Analysis Of Safety Aspects And Mining Practices For Effectiv|