Historically, the decision on whether to mine by underground or surface methods has been based on mining and economic considerations. This is rapidly changing since the environmental imperatives that have evolved over the past two decades are now a critical part of the decision process. As a result, quarry operations are increasingly considering the option of going underground. This research was carried out to identify the factors which would cause a surface quarry operator to consider the transition to underground mining. To identify the major incentives for going underground, primary factors influencing the decision for selecting underground mining over continued quarrying were investigated. Analysis of the literature and data gathered from site visits showed that significant benefits could be gained from mining underground, with respect to selected economic factors, environmental permitting and legal compliance, and post-production site usage for continued income. To determine mining characteristics of the typical surface quarry, data on the production phase (mining sequence) and environmental problems was collected from 18 quarries at various stages of their operating life spans. The data was obtained from sites in the Appalachian region of four states: Virginia, West Virginia, Maryland and Tennessee. Corresponding data was also gathered from successful underground operations to determine the values for a typical underground mine. Comparisons of this information indicated that the biggest differences between surface and underground operations existed in: the drilling and blasting phase, and in the haulage phase of the mining sequence; the size of the equipment; the extent of environmental concerns; and the potential for post-production income from the site. The process of environmental risk assessment was reviewed as a supporting tool to aid in the selection of underground over surface mining. By assigning probabilities of failure to specific, independent, environmental hazards, an operator can evaluate and compare the likelihood of success or failure operating as a quarry or underground mine. A case study from the data collected was used as an example to show how the procedure can be practically implemented. / Master of Science

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No description available.

The mechanisms of strata deformation due to underground mining were analyzed in an effort to better understand immediate roof behavior and surface displacements. Strata deformation characteristics above longwall and room-and-pillar mines in the eastern U.S. coalfields were evaluated and a numerical procedure was developed for calculating surface displacements. The model, based on the well-known finite element method, utilized empirical indices associated with subsidence engineering in order to incorporate the site-specific characteristics into the formulation. Different material behavior models and failure criteria were employed in an attempt to determine the areas highly deformed by underground excavation. Additionally, the method was sensitive to the ratios of the elastic moduli used to describe different rocks and/ or rock conditions, and not to the magnitude of the elastic properties. Thus, the use of arbitrary reduction factors to convert laboratory to in situ property values was completely avoided and scaling of the calculated surface displacements was based on, the empirically predicted, regional or local parameters. The use of fixed displacement nodes around an opening to induce failure overcame the roof-floor overlap problem encountered in other formulations. The successful implementation of the proposed methodology for modeling surface deformations complements and enhances existing prediction techniques, which are primarily based on empirical approaches, by allowing parametric analysis for different excavation geometrics, roof convergence curves and overburden properties. / Ph. D.

The mining of coal within 110 feet below a previously mined seam creates interaction effects which can be detrimental to work in the lower seam. These interaction effects are characterized by zones of very high stress and result in floor and roof instability and pillar crushing. Recent developments in the field of ground control make it possible to determine with a certain degree of confidence the location of these zones and estimate the degree to which the interaction will affect the lower seam. This information has been incorporated into a software package for microcomputers which will predict lower seam problems and suggest design criteria for minimizing the difficulties which will be encountered. / M.S.

The concept of encumbered space is recognized and defined. The components and their subcomponents are identified and isolated. The relative interactions between them are noted. Initial families of velocity-clearance curves for several haulage media are derived, noting the vital need for future research. The basic assumption that production is proportional to the product of capacity and velocity is utilized and the concept of derating the maximum theoretical production rate of an underground mining situation to obtain a more realistic estimate of the actual production rate is introduced. An example of the use of derating factors (derived from the results of questionnaires) in obtaining an estimate of production is presented. An order of magnitude check is made on the weighting of the initially selected derating factors. Results proved to be consistent, confirming the approach. Recommendations for future research are made. / Master of Science

no abstract provided by author / M.S.

The underground limestone mining industry is a small, but growing segment of the U.S. crushed stone industry. However, its fatality rate has been amongst the highest of the mining sector in recent years due to ground control issues related to ground collapses. It is therefore important to improve the engineering design, monitoring and visualization of ground control by utilizing new technologies that can help an underground limestone company maintain a safe and productive operation. Photogrammetry and laser scanning are remote sensing technologies that are useful tools for collecting three-dimensional spatial data with high levels of precision for many types of mining applications. Due to the reality of budget constraints for many underground stone mining operations, this research concentrates on photogrammetry as a more accessible technology for the average operation. Despite the challenging lighting conditions and size of underground limestone mines that has previous hindered photogrammetric surveys in these environments, over 13,000 photographic images were taken over a 3-year period in active mines to compile these models. This research summarizes that work and highlights the many applications of terrestrial close-range photogrammetry, including practical methodologies for implementing the techniques in working operations to better visualize hazards and pragmatic approaches for geotechnical analysis, improved engineering design and monitoring. / M.S. / The underground limestone mining industry is a small, but growing segment of the U.S. crushed stone industry. However, its fatality rate has been amongst the highest of the mining sector in recent years due to ground control issues related to ground collapses. It is therefore important to improve the engineering design, monitoring and visualization of ground control by utilizing new technologies that can help maintain safe and productive underground stone operations. Photogrammetry and laser scanning are remote sensing technologies that are useful tools for collecting three-dimensional spatial data with high levels of precision for many different mining applications. Due to the reality of budget constraints for many mining operations, this research concentrates on photogrammetry as a more accessible technology for the average operation, despite the challenging lighting conditions and expansive size of underground limestone mines that has previous hindered photogrammetric surveys in these environments. This research focuses on the applications of photogrammetry in underground stone mines and practical methodologies for implementing the techniques in working operations to better visualize hazards for improved engineering design and infrastructure management.

Mining into strata disturbed by previous mining operations either above or below may sometimes result in severe strata control problems. These interaction problems, associated with most multiple-seam mining operations, are very common in the Appalachian coal region and are the subject of this dissertation. On the basis of both theoretical and empirical analyses, using statistical analysis, numerical modeling, and photoelastic modeling methods in conjunction with the analysis of numerous case studies, a comprehensive, integrated model has been constructed and represented by a computer program called "MSEAM”. Using this comprehensive model, possible interaction problems under certain geological and mining conditions can be first predicted based on rules determined either empirically or statistically. Then, detailed analyses using different interaction mechanisms -- pillar load transfer, arching effect, upper seam subsidence, inner- burden bending, and innerburden shearing -- can further determine the area or degree of possible interaction in both under- and over-mining situations. Special geologic and mining factors controlling interaction are also summarized by indices for an independent interaction prediction. This integrated model has been validated by back·analysis of several case studies. Full descriptions of multivariate statistical analysis, photoelastic modeling technique, quantization of various interaction mechanisms, and development of the comprehensive model are included. / Ph. D.

This study is focused on developing a method to predict the dynamic behavior of mine tailings dams under earthquake loading. Tailings dams are a by-product of coal mining and processing activities. Mine tailings impoundments are prone to instability and failure under seismic loading as a result of the mechanical behavior of the tailings. Due to the existence of potential seismic sources in close proximity to the coal mining regions in the United States, it is necessary to assess the post-earthquake stability of these tailings dams. To develop the aforementioned methodology, 34 cyclic triaxial tests along with vane shear tests were performed on undisturbed mine tailings specimens from two impoundments in Kentucky. Therefore, the liquefaction resistance and the residual shear strength of the specimens were measured. The laboratory cyclic strength curves for the coal mine specimens were produced, and the relationship between plasticity, density, cyclic stress ratio, and number of cycles to liquefaction were identified. The samples from the Big Branch impoundment were generally loose samples, while the Abner Fork specimens were dense samples, older and slightly cemented. The data suggest that the number of loading cycles required to initiate liquefaction in mine tailings, NL, decreases with increasing CSR and with decreasing density. This trend is similar to what is typically observed in soil. For a number of selected specimens, using the results of a series of small-strain cyclic triaxial tests, the shear modulus reduction curves and damping ratio plots were created. The data obtained from laboratory experiments were correlated to the previously recorded geotechnical field data from the two impoundments. The field parameters including the SPT blow counts (N1)60, corrected CPT cone tip resistance (qt), and shear wave velocity (vs), were correlated to the laboratory measured cyclic resistance ratio (CRR). The results indicate that in general, the higher the (N1)60 and the tip resistance (qt), the higher the CSR was. Ultimately, practitioners will be able to use these correlations along with common state-of-practice geotechnical field methods to predict cyclic resistance in fine tailings to assess the liquefaction potential and post-earthquake stability of the impoundment structures.