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  • A Review of the Mechanics of Pillar Behaviour - Ken Mills - Published 2019

    In recent years, the drive to reduce the impacts of surface subsidence has led to mine layout designs that rely for their effectiveness on the long-term stability of pillar systems. This paper reviews the mechanics of coal strength behaviour inferred from laboratory testing of coal specimens as a context to better understand the appropriateness of different pillar design strategies. Laboratory testing of coal specimens to very high confining pressures (163 MPa) illustrates the independence of the two fundamental components of coal strength: cohesive strength and frictional strength. Testing of numerous coal samples from the same coal seam and coal samples from different coal seams illustrate the variability of cohesive strength. The significant influence of frictional strength when confining pressure is available is also apparent. These two fundamental components of coal strength combine to influence the range of pillar behaviours observed in practice. This paper explores the characteristics of these two components and their implications for the application of various pillar design approaches. A-Review-of-the-Mechanics-of-Pillar-Behaviour-Ken-Mills-Published-2019939 KB
  • Mechanics of Rib Deformation at Moranbah North Mine A Case Study - Yvette Heritage

    Moonee Colliery are longwall mining in the Great Northern seam at depths ranging from 90m to 170m. Surface infrastructure above the first four longwall panels includes the Pacific Highway and several residential and commercial properties.

    This paper describes the pillar design approach used to manage surface subsidence in the area. The approach is based on previous detailed subsidence and pillar monitoring in nearby Wallarah Colliery and measurements of subsidence throughout the Lake Macquarie area for a wide range of pillar sizes and overburden depths. Undermining the Pacific Highway requires consideration of not only the amount of subsidence but also the timing and nature of subsidence. Various options were considered and a design developed to control surface subsidence to acceptable levels. This paper summarises the results of previous monitoring and outlines the issues considered in the longwall panel design for subsidence control at Moonee Colliery. COAL-2018-Mechanics-of-Rib-Deformation-at-Moranbah-North-Mine-A-Case-Study-Y.Heritage-2018.pdf2.6 MB
  • Development and Application of Strata Management in Coal Mines - Stuart MacGregor

    The continuing need to improve productivity and safety requires mine operators to both successfully manage the hazards associated with strata control whilst optimising mining practices. Recent experience in Australian coal and metalliferous mines has seen the introduction of legislation to ensure that adequate consideration is given to geotechnical design and strata control.

    This paper outlines a rational approach for the development of a Roadway Strata Management System that is based upon the systematic assessment of strata behaviour during all stages of a roadways use and describes its application by Strata Control
    Technology Pty. Ltd. at Ulan Coal Mines Limited. Development-and-Application-of-Strata-Management-in-Coal-Mines-S.MacGregor-2005.pdf519 KB
  • Investigations Aimed to Improve Tailgate Serviceability at Dartbrook Mine - Ken Mills

    Dartbrook Mine has experienced rib control difficulties because of deterioration in the tailgate corner of the longwall face as overburden depth has increased. This paper summarises an investigation to optimise support and develop strategies to improve the serviceability of the tailgate roadways. Field measurements undertaken in the tailgate of Longwall 6 identified roadway softening mechanisms, deformation characteristics and factors controlling deformation. This provides the basis for optimising the reinforcement system as part of an ongoing Strata Management Plan at the mine. Investigations-Aimed-to-Improve-Tailgate-Serviceability-at-Dartbrook-Mine-K.Mills.pdf397 KB
  • Investigation into Temporary Roof Support Principles - Winton Gale

    An investigation was undertaken in regard to Temporary Roof Support (TRS) systems incorporated into miner bolters. Two and three dimensional modelling was utilised to document the effects a TRS system may have on the surrounding underground environment. TRS systems were found to have little if any effect on strata stability about a simulated roadway but are considered capable of providing protection against minor roof falls where the operator is within the defined protection zone. Each system requires the combination of mesh, bolts and support points to provide a protective zone to the operators. In difficult conditions there is no substitute for bolting as close to the face as possible and the concept of a zone of influence about a support point, as indicated by industry guidelines is not considered as a suitable protection zone. Investigation-into-Temporary-Roof-Support-Principles-W.Gale.pdf1.8 MB
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