The dynamic nature of coalbed methane reservoir permeability makes the continuous modeling of the flow process difficult. Knowledge of conventional reservoir modeling is of little value because the gas storage and flow mechanisms in coal are remarkably different. Field observations suggest that the gas productivity does not decline with time as expected. An increasing permeability is a possible explanation. This laboratory study is aimed at measuring the volumetric changes in coal matrix resulting from gas desorption, its impact on coal porosity and permeability, and an estimate of the stage when the effect is significant. Results using cylindrical samples of coal suggest that coal matrix shrinks with desorption of gas. The shrinkage is linearly proportional to the quantity of gas desorbed. Using the measured changes in matrix volume, variations in total and cleat porosity were estimated and found to increase significantly with desorption. These changes should, therefore, be used as input when simulating long-term gas production.

The success of rock fragmentation by blasting and subsurface fluid flow depends on many variables, including in-situ fragmentation. This study presents select data from a review of over 13000 feet of core samples drilled at seven different mine properties in the United States and Chile. Two-dimensional computer simulations of fractures can be used to quantify the volume of rock required to calculate a stable estimate of mean fragment size. Spatial periodicity of fragment size measurements is indicated through vertical variograms and is used as the basis for a statistical analysis for the zoning of rock masses. A more reliable quantitative method to characterize the size distribution of in-situ rock using digital image processing of drill core photographs is also included. Furthermore, a complete experimental analysis is provided for the comparison of currently used correction methods used to develop the full volumetric fragment size distribution curve.

Various filtering and integration techniques were used to analyze geologic, geophysical and geochemical data from the Twin Peaks area located in the DeLamar mining district in Southwestern Idaho. In particular rank correlation and favorability analysis were employed in this study. The data analysis was used to delineate target areas considered favorable for epithermal gold-silver mineralization. The interpretation of geophysical data was emphasized because of the importance of subsurface geologic features and complications caused by post mineral cover. Field investigation of the target areas provides strong evidence supporting the potential for significant mineralization in four of the twelve target areas selected.

<p>The flow of thickened mine tailings within a tailings storage facility is a complex interaction between unconstrained viscoplastic free surface flow and possible coarse particle settling within the flow depth. The broad focus of this work is developing a robust framework for modelling tailings beach flows. Modelling tailings flow evolution in three dimensions within a storage facility will ultimately provide greater understanding of beach slope formation, as well as the ability to optimize deposition sequencing. This thesis focuses on the first step of developing a tailings model considering the transport and settling of mono-sized coarse particles within two dimensional (length and depth) laminar viscoplastic carrier fluid sheet flow. The 2D model consists of a semi-implicit finite difference shallow water sheet flow model for predicting the viscoplastic flow depth and discharge down the beach. The coarse particle transport and hindered settling within the flow are predicted using a scalar transport model. The scalar transport and shallow water flow model are coupled together using coarse particle rheology augmentation. Two key novel advancements were made through the model development. The first is coupling the coarse particle rheology augmentation within the free surface flow to the coarse particle hindered settling behavior with depth. This coupling allows for the rheology augmentation due to the coarse solid fraction to be incorporated seamlessly into both the fluid flow solver and the particle settling model. The second advancement is expanding the rheology augmentation and hindered settling coupling to particle flows beyond the Stoke?s flow regime. Ultimately, the 2D model results are compared against Spelay?s (2007) laminar settling experimental measurements for oil sand thickened tailings (TT) and composite tailings (CT) slurries, along with Spelay?s 1D settling model. The 2D model provides improved prediction of the particle concentration profiles within the fluid flow compared to the 1D model. The 2D model is also able to predict the increase in flow depth due to the particle accumulation on the bed, as well as the downslope particle transport and settling behavior.

<p> Unstable failure in underground mining occurs when a volume of material is loaded beyond its strength and displaces suddenly. It is recognized on various scales, from small rock bursts to the collapse of pillars or entire sections of a mine. The energy that is released during smaller scale events is manifested through the ejection of material, which can pose a hazard to the safety of miners. Larger scale events generate seismic waves as mine workings are damaged and may entrap miners or terminate production. </p><p> This dissertation focuses on the analysis of unstable failure in an underground room and pillar mining environment. The potential for violent pillar failure is assessed using numerical modeling techniques and a parametric approach to loading conditions and material strength properties. The magnitude of instability is quantified by calculating the release of kinetic energy that occurs as failure progresses in each simulation. </p><p> Fundamental mechanisms associated with the release of kinetic energy are analyzed in a series of finite difference models, and the results are compared with analytical solutions to illustrate the applicability of the energy calculations to increasingly complex modes of failure. Back analyses are performed on two room and pillar mine collapse events from the western United States by constructing large-scale models and reproducing widespread failure. The values of energy released in two-dimensional models are extrapolated by assuming a depth of failure in the third direction, and the total energy values are compared to the documented seismic magnitudes from each collapse through empirical equations. With further development of this numerical modeling approach, energy consideration may be used to study the potential for instability in a wide variety of mining excavations and identify the associated range of hazards.</p>

The Bagdad Mine, an open pit mine located in northwestern Arizona, has experienced a slope failure related to a weak weathered tuff bed. The unit has been altered to a clay-like material in areas of the pit. Overburden pressures have caused the tuff to be squeezed out, and blocks of the overlying basalt unit have toppled forward. The failure has been remedied by reducing the pit slope to about 20°, but this solution is not desirable. Modelling of the slope is done using a general purpose finite element method program. The Drucker-Prager theory is used to model the tuff bed, while the other units are treated as being linearly elastic. Material properties for the three rock units are obtained from a variety of sources. Results suggest that loss of shear strength in the tuff, due to blasting-induced liquefaction, may be the cause of slope failure. Suggestions are made for remedial action.

In traditional growth theory, the terms of trade are important growth factors. However, the new exported growth hypothesis suggests that shifting from resource to innovation rents via the free market trade mechanism accelerates growth. Given its revealed comparative advantages in natural resources, Namibia is attempting to apply World Bank, and UNIDO new growth criteria to stimulate economic growth. This research analyzes Namibia's data from 1968-1992, estimates the impacts and tests the significance of resources, technology, and mineral exports in economic growth. It assumes variable elasticity of substitution (VES) production technologies in which capital, labor, and land inputs can be disaggregated and hypotheses concerning scale, complementary and substitute inputs can be examined. A disaggregated examination of traded and nontraded sectors is employed over two sub-periods: 1968-1980, and 1981-1992. The analysis confirms the importance of mineral exports to the economy but finds no discernible sign of accelerated growth as a function of the shifting structure and the new growth criteria. The attempt to shift from resource rents in the early period to an industrial emphasis in the later period fails to accelerate Namibia's growth. Global constant returns to scale pre-1980, and diminishing returns to scale post-1980 obtain. The switch from complementary and flexible substitute inputs pre-1980 to rigid substitutes post-1980 suggests technical inefficiencies. The vent-for-surplus nature of the mineral subsector is supported; but attempts to industrialize via manufacturing are not vindicated, and the surplus arising pre-1980 dissapates post-1980, as evidenced by the low or negative factor productivities and technical change. The result is that neither the expected growth nor acceleration in technical change patterns are observed. Policies seem to have discouraged investment in the traded resource sectors such that structural changes expanded the low productivity nontraded service sectors. Namibia is a vent-for-surplus example in which resource rents do not sustain early economic growth, and attempts to shift to innovation rents fail to stimulate growth. Given the paucity of data, Namibia's case confirms that export surpluses from resources may be a necessary element, but not a sufficient condition, for sustainable growth.

Accurate quantification of roughness is important in modeling strength, deformability and fluid flow behaviors of joints. Both stationary and non-stationary fractional Brownian profiles with known values of the fractal dimension and other profile properties were generated. The generated profiles were in general quite similar to the roughness profiles of natural rock joints. For different values of the input parameter of the line scaling, variogram and roughness-length methods, D was calculated for the generated self-affine profiles to investigate the accuracy of each method. The results obtained are used to suggest guidelines to calculate fractal-based roughness parameters accurately for natural rock joint profiles. It is important to know the strength of rock discontinuities in different directions in dealing with rock engineering systems which are subjected to various external forces. The roughness of a natural rock joint was measured in different directions using a laser profilometer. A model material which is a mixture of plaster of Paris, sand and water was used to make model material replicas of the natural rock joint. Direct shear tests were performed on rough model material joints at five different normal stresses, in the same directions which were used for the roughness measurements. The scratched areas on rough joints resulting from direct shear tests were used along with the joint surface topography to estimate the asperity shear area of the joints. Direct shear tests were conducted on smooth model material joints to estimate the basic friction angle. Required tests were conducted on intact model material to develop a peak shear strength criterion for the intact model material. The direct shear data obtained on the rough joint for 3 of the 5 normal stresses were used along with other laboratory test results to develop a new peak shear strength criterion which includes two fractal based stationary roughness parameters, a non-stationary roughness parameter, basic friction angle, normal stress, joint compressive strength, intact shear strength and area of asperity shear as a proportion. The developed criterion was used to predict the peak shear strength in different directions at the other two normal stresses which were not used in developing the peak shear strength model. The comparison between the predictions and the measured values showed that the new peak shear strength criterion has the capability to predict anisotropic peak shear strength accurately. In practice, to allow for modeling uncertainties, the new criterion should be used with a factor of safety of about 1.5.

A simplified version of a model that accounts for distributed damage in brittle materials is adopted. It is then extended for the study of the effects of random initial inhomogeneity on material response. A model case regarding random initial inhomogeneity in a structure (specimen) subjected to uniform static compression is studied by including pre-processing and appropriate modifications to a general two dimensional finite element program. From the numerical calculations obtained, the character of damage growth in brittle materials is then studied and discussed.

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