A boundary element model was developed for stress/stability analysis of underground excavations in the vicinity of faults. The boundary element formulation adopts the Fictitious Stress Method for the simulation of excavation boundaries and the Displacement Discontinuity Method for the representation of faults. With the assumption that deformations and stress changes can generally be attributed to the presence of faults rather than to elastoplasticity of the rock mass, the numerical model employed a linear elastic constitutive relation for the rock, and nonlinear behaviour for the fault. This assumption is particularly justified in hard rock environment. Following a comprehensive review of constitutive models for rock joints, both deformation and peak strength models were incorporated for modelling the mechanical behaviour of the fault. Deformation or stiffness models include Goodman's constant stiffness model and Barton-Bandis' nonlinear model. The latter, considers the effect of a wide range of parameters such as coupling between shear and normal stresses and displacement, joint closure, joint separation, hardening followed by postpeak or residual behaviour. Peak strength models include Mohr-Coulomb and Barton-Bandis which employs a mobilized nonlinear shear strength envelope. An incremental, in situ stress relaxation algorithm is developed and implemented for the nonlinear analysis of the faults. / Model verification was done by a comparison of its predictions with previously published results found in the literature. The comparison showed excellent agreement. A model sensitivity analysis was then carried out to compare the response of different discontinuity models. A case study of an underground hard rock mine was conducted to examine the stability of a mining ore zone intersected by faults. / A user friendly graphical interface was developed to help generate the data and interpret the output results more efficiently.

This thesis investigates in detail the stress memory of hard rocks under uniaxial compressive conditions as a time-saving and inexpensive alternative to traditional in-situ stress measurement techniques. Extensive laboratory experiments are carried out to assess the influence of parameters such as transducer/amplifier frequency response, signal definition parameters, stress rate, strain rate, specimen size, stress level, delay time, temperature, water content, confining pressure, and directional loading on the Kaiser Effect of Stanstead granite and other rock types. Based on these findings and a new data processing techniques developed for estimating the previous stress level, a testing procedure is suggested and used to determine in-situ stresses from core samples with respect to their drilling orientations. In two case studies, the estimated stresses using the Kaiser Effect phenomenon are in good agreement with values obtained from conventional techniques while in the third study, no stress value was obtained due to the inability of the rock type to generate acoustic emissions. The results of this investigation show that the Kaiser Effect could become an economical method of stress measurement in hard and isotropic rock types.

Particle behaviour during the downwards, pneumatic injection of powder into an aqueous medium (water) has been investigated by means of a new method which involves direct measurement by making use of an Aqueous Particle Sensor (APS) unit. Through this method, phenomena and parameters related to injection processes, such as gas-particle jet penetration distance, jet diameter, jet cone angle, particle dispersion and distribution within the liquid have been investigated both qualitatively and quantitatively. Flow observations comprised part of the experimental program for the purpose of confirming the characteristics of the "gas-only" and "gas-powder" injection regimes reported by previous workers. / The effect of gas and powder flow rates (powder/gas loading ratio) in determining the injection regimes and particle behaviour within the liquid were the main parameters investigated. / It was demonstrated that the jetting regime can be easily achieved as a result of increased momentum transfer from the particles to the gas phase. However, this required a high loading of particles. Entrainment of gas with the injected particles took place not only during coupled flow (jetting) but also during decoupled (bubbling) flow, such that some gas was always entrained by the particles and penetrated the liquid as a gas-particle jet, leaving large gas bubbles at the lance tip. It was further demonstrated that the gas flow rate had a greater effect on particle suspension within the liquid than did the powder flow rate.

In this thesis the behavior of fully grouted, untensioned cable bolts and their application to the stabilization of underground openings are investigated. The study program undertaken involves field, laboratory and numerical studies which aim to improve understanding of the role of passive cable bolting in rock mass support. The higher residual load carrying capacity of the cable and the grout-aggregate mix is compared with that of the conventional grout (cement + water). / Based on the variational approach, an analytical model has been developed to calculate the distribution of shear bond stress along the embedded length of a cable bolt. A parametric study is then undertaken to illustrate the support behavior of cable bolts with different grout compositions. / A special finite element for the cable bolt was formulated and integrated into existing finite element code called MSAP2D, in order to allow the simulation of cable bolts in underground excavations. / A practical example is presented to demonstrate the effect of cable bolts on the stability of the opening. The simulation is carried out using the newly developed numerical model with cable bolt simulation capability.

Regardless of the objective sought, the conclusions drawn from seismic monitoring can only be as good as the quality of the recorded data: the importance of properly capturing relevant raw vibrational information in the first place is thus absolutely crucial. The difficulty is that blast-induced vibration monitoring is site specific and that general formulas do not apply: every situation will correspond to a unique combination of objectives, ground conditions, blast design and explosive types, and will need to be monitored accordingly. To adequately acquire all the pertinent seismic information, a number of points must be successfully addressed, such as the choice of sensors, their location, number, orientation and anchoring, the transmission of the captured signals from these gauges to the recording equipment, and the choice and set-up of the data acquisition system. / It is the purpose of this thesis to address these questions in some detail, in an attempt to provide the reader with an understanding of how all the components involved in blast-induced vibration monitoring interact, and on how the choices made at each step can significantly affect overall results. (Abstract shortened by UMI.)

The steeply dipping vein orebody of Bousquet 2 mine is extracted by sublevel open stope method. The presence of structural discontinuities, high induced stress distribution, and narrow stope widths are major factors which can seriously affect ore dilution. Therefore, strict ore dilution control is necessary in order to keep the mine competitive. The thesis describes the selective mining method adapted to this type of orebody, and subsequent measures taken to minimize ore dilution. For this study, the locations of stress relaxation are taken as failures zones. Therefore, these zones are more important since they are subjected to very low stresses which can provoke rock block sliding or local wall caving (tension failure). Tracing the zone of tensile stress in the stope wall gives reasonable prediction of dilution and permits to calibrate the numerical model using the field data obtained from the cavity Monitoring System (CMS). Stope mining is made in several cuts according to the width of the ore zone. For an improved recovery, some stopes are mined using primary and secondary stoping. Blasthole pattern and mining sequences are closely linked to the ore zone configuration. The main causes of ore dilution are summarized. They are a combination of several factors such as ground conditions, blasting damage, state of stresses around the stope, and stope design. In order to minimize ore dilution from hanging-wall and foot-wall, cable support is installed. Numerical modelling is carried out for a typical cable bolt pattern. The results of modelling have demonstrated that the cable bolts were necessary to control hanging wall caving. This is accompanied by a reduction of ore dilution. Consequently the study has shown the effectiveness of cables bolt as pre-support of the schistose walls in Bousquet sublevel stoping environment.

Isolated high grade and low tonnage uranium ore pods are prevalent in Saskatchewan. This thesis reviews mining such a pod with both conventional and unconventional methods. The geomechanical characteristics of the overburden and the bedrock in the area of the pods must be investigated before evaluating the technical feasibility of possible mining methods. Conventional ore recovery techniques appraised include open pit and underground mining. The unconventional mining techniques considered are blind boring and jet boring from surface. These last two techniques can offer a greater degree of selectivity, although ground reinforcement techniques had to be considered due to the poor quality of the ground. Ground reinforcement techniques considered were shaft lining, grouting, and ground freezing. This mining design challenge was found to be feasible with the combination of jet boring and freezing. Recommendations are presented to define future areas of study for blind boring, jet boring, grouting, and freezing.

Composite material tendons are considered in this thesis as interior ground support for underground excavations. The physical and mechanical properties of composite tendons critical to mining requirements were identified. Preliminary laboratory investigations were also undertaken to evaluate their performance as fully grouted reinforcing tendons. Arapree, a flexible tendon, and Weldgrip, a solid tendon, are the two patented composite tendons found to be superior in pull out testing. Their load carrying capacity and ductility in the elastic range is similar to that of existing steel supports, although their post peak performance is different. Rigid composite bolts have more load sustaining capacity than their steel counterparts, while flexible composite tendons have less capacity than conventional seven wire flexible steel cable. The shear capacity of fully grouted Weldgrip bolts was found to be in the range of 100 kN. As part of studies of flexible tendons, conventional steel cable was also used to investigate other parameters, since it was found to be identical in pull out behaviour to composite flexible cable. It was found that the effect of grout strength and modulus, radial confinement and host medium strength and stiffness is significant in controlling the performance of steel cable. The laboratory investigation also found that different grouting materials, such as conventional to high strength cement grout and polyester resin grout greatly influence the pull out performance of both steel and composite tendons.

Disposal of acid generating sulphidic tailings is a major environmental problem facing the Canadian as well as the international mining and mineral industries. If the deposited tailings are not treated the sulphide minerals oxidise and create an acidic environment. The leachate from such a site is rich in soluble heavy metals and has the potential to contaminate the groundwater as well as the local surface watercourses. This thesis explores an alternative treatment method via ettringite formation, which stabilises and solidifies these highly reactive tailings. / Ettringite has the capacity of uptaking other metals into its structure by isomorphous substitution. Ettringite has also a negative surface charge, which makes it a good adsorbent for positively charged cations. Furthermore, the high pH solution required for ettringite formation will cause the precipitation of heavy metals from the solution. Therefore, ettringite in a lime-remediated sulphate rich acid mine drainage system could serve as a physical and chemical stabilization agent, which could also reduce the remediation costs over other commercially available stabilization technology. / In order to assess the feasibility of forming ettringite in sulphide rich tailings, a thermodynamic model was used to investigate the optimal geochemical parameters. The model predicts that ettringite is stable over a wide range of compositions and pH. Results presented in this thesis show that the sulphate content of the tailings samples could limit the precipitation of ettringite, and monosulphate could be the end-precipitate. / Long-term leachability and durability analysis showed that ettringite can be formed as a stable mineral in lime, fly ash, and aluminum rich sulphidic tailings samples. Ettringite formation reduced the leachability of the heavy metals and improved the geotechnical characteristics of the treated samples. Freeze and thaw analyses showed that formation of ettringite produce a low permeability and high strength tailings sample capable of withstanding harsh environmental fluctuations.

This thesis aims to develop a comprehensive strategy for automatic control of the ITH percussive drilling process. Such automation would provide the benefits of improved productivity and quality in terms of penetration rate and hole deviation, as well as enhanced hole quality and machine life. / Analysis of field data acquired from drilling experiments performed at INCO's Little Stobie Mine is presented. As a result of this analysis, a control algorithm is formulated to enhance the drilling process efficiency. This algorithm calculates the specific energy (SE) of the rock and adjusts the applied feed force based on this SE value, using a relationship obtained from the field data analysis. / A model of the percussive drilling process is developed and simulated in software. The proposed control algorithm is tested through simulations on this simulated drilling process. The results of the simulation show a significant increase in efficiency of the drilling process. / As a result of vibration data analysis it is concluded that vibration should be controlled through an improved design of the shock-absorber, rather than through drilling variables. A detailed shock-absorber test data analysis is therefore presented. Recommendations for design changes in the shock-absorber are also given. / Deviation analysis is also presented in the thesis, which shows a poor correlation between the machine variables and the hole deviation data. Hence, it is recommended that deviation be controlled by steering. An innovative guided drilling mechanism for controlling the hole deviation is also proposed. This mechanism consists of an eccentric ITH percussive hammer with controlled rotational speed, which can be employed as an actuator to steer the drill string in a desired direction without using any down hole instrumentation. Modelling and simulation analysis of this system is also presented.