Thesis (M.S)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xi, 104 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 69-70).

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xviii, 163 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 159-162).

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, 2000. / Title from document title page. Document formatted into pages; contains xii, 140 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 120-122).

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xi, 65 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 63-64).

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Spontaneous combustion occurring in inaccessible areas of underground coal mines is often intractable. Even though routine inspection and/or continuous monitoring help detect the incubation of spontaneous heatings, they may not be able to identify the locations with accuracy. Moreover, implementation of remedial measures is difficult. A new approach to ventilation system design to overcome the problem is investigated in this dissertation. Ventilation layouts are analyzed to identify potential problem areas and nullify the probability of fire occurrence. The focus is directed to longwall gobs. The changing gob characteristics, especially the varying degree of consolidation at different parts of a gob as the face moves, is considered. Analytical studies and computer modeling show that bleederless ventilation in retreating panels is promising. The W -system of ventilation is most suitable. However, there may be difficulties in maintaining the middle entry in a Wsystem / Ph. D.

Photogrammetry and laser scanning are remote sensing technologies with the potential to monitor movements of rock masses and their support systems in underground mine environments. Displacements underground are traditionally measured through point measurement devices, such as extensometers. These are generally restricted to measuring one dimension, may change behavior with installation, may obstruct mining operations, and are restricted to monitoring the behavior of a small area. Photogrammetry and laser scanning offer the ability to monitor rock mass movements at millions of points in a local area, both accurately and quickly. An improved, or augmented, method for measuring displacements underground in a practical, cost-effective manner will lead to an improved understanding of rock mass behavior. Several experiments were performed that demonstrate the applicability of these remote sensing techniques to monitoring rock mass changes. An underground mining environment presents unique challenges to using these tools for monitoring rock movements, such as: poor lighting, dust, fog, and unfavorable geometries. It is important, therefore, to demonstrate that these tools which have applications in other industries, can also be adapted to the conditions of an underground mine. The study sites chosen include two different underground limestone mines, two different underground coal mines, and the Mine Roof Simulator (MRS) at the Pittsburgh Office of Mine Safety and Health Research. Both photogrammetry and laser scanning were tested at different limestone mines to detect scaling and spalling on ribs that occurred over several weeks. Both methods were successfully used to reconstruct three-dimensional models of the limestone ribs and detect areas of rock change between visits. By comparing the reconstructed point clouds, and the triangulated meshes created from them, volumes of rock change could be quantified. The laser scanned limestone mine showed a volume of 2.3 m3 and 2.6 m3 being displaced across two ribs between visits. The photogrammetry study involved seven different pillars and at least one rib face modeled on each, with volume changes of 0.29 to 4.03 m3 detected between visits. The rock displaced from the ribs could not be measured independently of the remote sensing, but a uniform absence of rock movement across large areas of the mine validates the accuracy of the point clouds. A similar test was performed using laser scanning in an underground coal mine, where the displacement was induced by removing material by hand from the ribs. Volume changes as small as 57 cm3, or slightly larger than a golf ball, and as large as 57,549 cm3, were detectable in this environment, despite the change in rib surface reflectance and mine geometry. In addition to the rib displacement, photogrammetry was selected as a tool for monitoring standing supports in underground coal mines. The additional regulatory restrictions of underground coal may preclude the use of laser scanning in these mines where deformation is most likely to occur. The camera used for photogrammetry is ATEX certified as explosion proof and is indicative of the specifications that could be expected in an MSHA approved camera. Three different experiments were performed with this camera, including a laboratory controlled standing support deformation at the MRS and an in-mine time-lapse experiment measuring the response of a wooden crib and steel support to abutment loading. The experiment reconstructing a standing support in the MRS showed a cumulative convergence of 30.93 cm through photogrammetry and 30.48 cm as measured by the system. The standing support monitoring in the underground coal mine environment showed a steel support cumulative convergence of 1.10 cm, a wooden crib cumulative convergence of 0.62 cm, and a measured cumulative convergence on the wooden crib of 0.62 cm. These techniques explored in this report are not intended to supplant, but rather supplement, existing measurement technologies. Both laser scanning and photogrammetry have physical and regulatory limitations in their application to measuring underground mine deformations, however, their ability to provide time-lapse three-dimensional measurements of entire mine sections is a strength difficult to emulate with traditional point measurement techniques. A fast, cost-effective, and practical application of remote sensing to monitoring mine displacements will improve awareness and understanding of rock mass behavior. / Ph. D.

This dissertation reports on research efforts to investigate, analyze, and model longwall face-to-face transfers through the use of operations research techniques. The purpose is to reduce overall transfer time and the variation of transfer times among operations within the U. S. longwall industry. The research includes: (1) investigation of existing longwall transfers to determine standard and variant procedures; (2) development of comprehensive activity sequence models of existing longwall transfers; (3) generation of a simulation model for longwall transfers in various geological and mining conditions; and, (4) investigation of the economic feasibility of time-cost tradeoffs in the transfer procedure. Face transfer field data were collected from three eastern U.S. mining operations. From these data, general operational characteristics, transfer personnel utilization, and transfer procedures are described. A comparison of methods provide a breakdown of transfer activities, identify critical activities, and establish the state-of-the-art in transfer technology. Project scheduling models are developed for each operation using precedence networking analytical techniques and are applied through a computerized commercial software package. The project scheduling models accurately represent each of the operations' transfer procedures and provide information on the criticality of transfer activities and estimated project duration. Simulation models are developed, using Monte Carlo techniques, to combine analytical project scheduling with probability-based transfer activity durations. The simulation models closely match the results of the project scheduling models and provide information on the statistical tendencies of critical activities, paths, and project durations. The economic feasibility of reducing transfer time is analytically evaluated by collapsing critical activities and attempting an alternative roof control method. When compared to the lost production potential of longwall mining systems, the two time-cost trade-off procedures are proven, by the transfer simulation model, to be economically viable. This research is expected to contribute to the longwall mining industry by offering an objective approach that can be used in the prediction, planning, preparation, and implementation of longwall face equipment transfers. / Ph. D.

Dust is a detrimental, but unavoidable, consequence of any mining process. It is particularly problematic in underground coal mining, where respirable coal dust poses the potential health risk of coal workers’ pneumoconiosis (CWP). Float dust, if not adequately diluted with rock dust, also creates the potential for a dust explosion initiated by a methane ignition. Furthermore, recently promulgated dust regulations for lowering a miner’s exposure to respirable coal dust will soon call for dramatic improvements in dust suppression and capture. Computational fluid dynamics (CFD) results are presented for a research project with the primary goal of applying a flooded-bed dust scrubber, with high capture and cleaning efficiencies, to a Joy 7LS longwall shearer operating in a 7-ft (2.1 m) coal seam. CFD software, Cradle is used to analyze and evaluate airflow patterns and dust concentrations, under various arrangements and conditions, around the active mining zone of the shearer for maximizing the capture efficiency of the scrubber.