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This thesis is a theoretical investigation into the time-dependent behaviour of rock joints. Much of the research work that has been conducted to date in the area of finite element analysis has been involved with the development of special elements to deal with these discontinuities. A comprehensive literature survey is undertaken highlighting some of the significant contributions to the modelling of joints. It is then shown how internal variables can be used to model discontinuities in the rock mass. A finite element formulation is described resulting in a system of equations which can easily be adapted to cope with various constitutive behaviours on the discontinuities. In particular, a viscoplastic relationship; which uses a homogeneous, hyperbolic yield function is adopted. The viscoplastic relationship can be used for both time-dependent (creep) or quasi-static (elasto-plastic) problems. Time-dependent behaviour requires a time integration scheme and therefore a generalised explicit/implicit scheme is chosen. The resulting numerical algorithms are all implemented in the finite element program, NOSTRUM. Various examples are presented to illustrate certain features of both the formulation and the numerical algorithm. Jointed rock beams and a jointed infinite rock mass are modelled assuming plane strain conditions. Reasons are proposed to explain the predicted behaviour. The results of the analysis shows that the internal variable formulation successfully models time-dependent joint movements in a continuous media. The method gives good, qualitative results which agree with observations in deep level mines. It is recommended that quantitative mine observations be used to calibrate the model so that usable predictions of joint movement can be made. This would enable any new developments to be implemented in the model. Further work on implicit methods might allow greater modelling flexibility by reducing computer run times.

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A range of seismic images likely to be encountered from stream-cut channels is examined with ray tracing computer modeling. The channel shapes, sizes, depths of burial, and associated geologies are examined to determine their effect on seismic images, waveforms, and ultimate interpretation. The study uses channel geometries taken from the Pulaski, Bush City, Moberly, and Nesvacilka channels which are assumed to he at various depths of burial. Results show that seismic sections often do not approximate geologic cross sections, that seemingly random reflections have geologic meaning, and that channels can be detected by their effects on the amplitude and shape of lower reflectors. The resolution of channels is summarized in tables of resolvability.Ball State UniversityMuncie, IN 47306

A computer-based method for determining the orientation of planar geological structures from remotely sensed images, utilizing digital geological images and digital elevation models (DEMs), is developed and assessed. The method relies on operator skill and experience to recognize geological structure traces on images, and then employs software routines (GEOSTRUC©) to calculate the orientation of selected structures. The operator selects three points on the trace of a planar geological feature as seen on a digital geological image that is co registered with a DEM of the same area. The orientation of the plane that contains the three points is determined using vector algebra equations. The program generates an ASCII data file which contains the orientation data as well as the geographical location of the measurements. This ASCII file can then be utilized in further analysis of the orientation data. The software development kit (SDK) for TNTmips v5.00, from MicroImages Inc. and operating in the X Windows environment, was employed to construct the software. The Watcom C\C++ Development Environment was used to generate the executable program, GEOSTRUC© . GEOSTRUC© was tested in two case studies. The case studies utilized digital data derived from the use of different techniques and from different sources which varied in scale and resolution. This was done to illustrate the versatility of the program and its application to a wide range of data types. On the whole, the results obtained using the GEOSTRUC© analyses compare favourably to field data from each test area. Use of the method to determine the orientation of axial planes in the case study revealed the usefulness of the method as a powerful analytic tool for use on a macroscopic scale. The method should not he applied in area with low variation in relief as the method proved to be less accurate in these areas. Advancements in imaging technology will serve to create images with better resolution, which will, in turn, improve the overall accuracy of the method.

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Hydrogeochemical studies are generally qualitative in nature. The goal of this study is to investigate the possibility of quantitative interpretation of hydrogeochemistry by considering the chemical characteristics and the isotopic compositions of oxygen, hydrogen, and carbon of the water. This study examines ephemeral stream and well waters from Canada del Oro valley, southern Arizona. By chemical and isotopic considerations, this study finds that the change of chemical composition of the wash water was mainly due to water-rock interaction. The concentrations of dissolved constituents increase between 10 to 50% from upstream to downstream samples, while the evaporation loss of water is less than 3%. By chemical and isotopic considerations of the well waters, this study identifies three recharge waters in the CDO ground-water system. The chemical and water isotopic compositions of the well waters are results of mixing between these three recharge waters and subsequent dissolution of the aquifer. By thermodynamic consideration, albite, kaolinite, montmorillonite, and calcite are the main phases that influence the chemical characteristics of this ground-water system. Simulations with the computer program PHREEQE verifies the above conclusions. The mechanisms that influence the chemical and carbon isotopic compositions of the water are quite different in a system open to a CO2 gas reservoir than in a closed system. Deines, Langmuir, and Harmon (1974) derived a set of chemical-isotopic equations to calculate the carbon isotopic composition of water under open system condition. Wigley, Plummer, and Pearson (1978) formulated a mass transfer equation to calculate the change of carbon isotopic composition of natural water in closed system environment. This study implements these two type of equations as a subroutine--CSOTOP to the computer program PHREEQE. With this PHREEQE-CSOTOP package, the evolution of carbon chemical and isotopic composition of natural water can be conveniently modeled from open to closed system conditions. This study also uses this package to date water samples from the Tucson basin, and finds that choice of reaction path may cause a difference in carbon-14 age of up to a few thousand years. This study concludes that it is possible to rigorously interpret hydrogeochemistry in a quantitative way. With sufficient measurements to define the reaction path, followed by thermodynamic consideration, chemical-isotopic evaluation, and computer modeling, one should be able to achieve this goal.