Tailgate stability within longwall coal mining is critical to longwall productivity and safety of mine personnel. A mechanistic model was developed and tested to explain observed high deformation tailgate behaviour characterised by lateral strata movement. Field investigations were conducted at three Australian longwall mines with an emphasis on the measurement of; horizontal strata movement about gateroads during longwall extraction, and the load/deformation characteristics of standing supports. 3D numerical modelling was used to simulate tailgate deformation, and interaction of various support types and design strategies. The sensitivity of strata and support behaviour to; variations in roof geology, strength of sliding interfaces, depth of cover, pre-mining horizontal stress magnitude and orientation, and strength and stiffness characteristics of standing supports was modelled. Laboratory investigations of a standing support product, the ???Can???, at reduced scale (one third) were conducted. The tests determined the loading mechanics of the product and provided a basis for optimisation of the engineering properties (strength and stiffness). Horizontal strata movement about longwall extraction was found to have a significant impact on strata behaviour at two of the three mines investigated. The term ???skew roof??? was coined to describe the deformation process. Essentially the roof strata was found to ???skew??? towards the approaching goaf. The key geotechnical factors found to control the skew roof mechanism were; magnitude and orientation of the pre-mining horizontal stress, presence of weak interfaces along which sliding could occur, and shear strength of the interfaces. Measurement of the nature and extent of skew roof deformation specific to each mine provided a sound engineering basis for support design. These included; the relative roles of long tendons versus standing support, optimal pattern (position across and along the roadway) of standing supports, and appropriate strength and stiffness characteristics. The findings were successfully implemented at Metropolitan Colliery in particular, where adequate tailgate serviceability has been achieved within a high deformation environment, and whilst maintaining a relatively small chain pillar width. The research has achieved an alternative to empirical and trial and error tailgate support design methods.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xiii, 82 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 65-66).

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xiii, 379 p. : ill. (some col.), maps (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Pennsylvvania, 1933. / Published also without thesis note. eContent provider-neutral record in process. Description based on print version record. "Seleted bibliography": p. 213-218.

Thesis (Ph. D. (Economics))--University of Pretoria, 2003. / Includes bibliographical references (leaves 174-181).

Thesis (M.A.)--Marshall University, 2003. / Title from document title page. Document formatted into pages; contains vi, 51 p. Includes bibliographical references (p. 48-51).

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xiv, 158 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 141).

Graduate

Contentions that expansion of the British coal mining industry into predominantly rural areas may pose serious threats to agriculture and food production are reviewed in the light of the available evidence. It is considered that, whilst the severity of impacts and rate of future development may have been overstated, the conflicts are sufficiently significant to warrant close examination. Further, land use planners are responding for the first time to mining proposals affecting entire coalfields, thus making it essential to establish the correct principles of development from the outset. It is noted that past assessments of agricultural impacts have failed to reflect their diverse and pervasive nature, thus necessitating the identification of more appropriate methods of forecasting. In the light of current weaknesses in practice, it is argued that a formal system of impact assessment may prove necessary. Those characteristics of mining operations and associated end-uses which are likely to affect agriculture are analysed, as are those aspects of the farm enterprise most vulnerable to disruption. These various characteristics are then used as a basis for the assessment of mining-agriculture impacts. A review of the strategic nature of impacts arising from mining programmes is considered desirable, and limited proposals are made regarding assessment at this scale. More detailed consideration is given to an appraisal framework for individual mining proposals, and this is tested in relation to part of the 'Vale of Belvoirl coalfield. It is concluded that, although further methodological refinements and field investigations are necessary, the early implementation of an impact assessment procedure is nevertheless justified.

Tailgate stability within longwall coal mining is critical to longwall productivity and safety of mine personnel. A mechanistic model was developed and tested to explain observed high deformation tailgate behaviour characterised by lateral strata movement. Field investigations were conducted at three Australian longwall mines with an emphasis on the measurement of; horizontal strata movement about gateroads during longwall extraction, and the load/deformation characteristics of standing supports. 3D numerical modelling was used to simulate tailgate deformation, and interaction of various support types and design strategies. The sensitivity of strata and support behaviour to; variations in roof geology, strength of sliding interfaces, depth of cover, pre-mining horizontal stress magnitude and orientation, and strength and stiffness characteristics of standing supports was modelled. Laboratory investigations of a standing support product, the ???Can???, at reduced scale (one third) were conducted. The tests determined the loading mechanics of the product and provided a basis for optimisation of the engineering properties (strength and stiffness). Horizontal strata movement about longwall extraction was found to have a significant impact on strata behaviour at two of the three mines investigated. The term ???skew roof??? was coined to describe the deformation process. Essentially the roof strata was found to ???skew??? towards the approaching goaf. The key geotechnical factors found to control the skew roof mechanism were; magnitude and orientation of the pre-mining horizontal stress, presence of weak interfaces along which sliding could occur, and shear strength of the interfaces. Measurement of the nature and extent of skew roof deformation specific to each mine provided a sound engineering basis for support design. These included; the relative roles of long tendons versus standing support, optimal pattern (position across and along the roadway) of standing supports, and appropriate strength and stiffness characteristics. The findings were successfully implemented at Metropolitan Colliery in particular, where adequate tailgate serviceability has been achieved within a high deformation environment, and whilst maintaining a relatively small chain pillar width. The research has achieved an alternative to empirical and trial and error tailgate support design methods.