Percussion drilling and trepanning are two laser drilling methods. Percussion drilling is accomplished by focusing the laser beam to approximately the required diameter of the hole, exposing the material to one or a series of laser pulses at the same spot to melt and vaporize the material. Drilling by trepanning involves cutting a hole by rotating a laser beam with an optical element or an x–y galvo-scanner. Optical trepanning is a new laser drilling method using an annular beam. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting the hole quality than a traditional circular laser beam. Heating depth is important for drilling application. Since there are no good ways to measure the temperature inside substrate during the drilling process, an analytical model for optical trepanning has been developed by considering an axisymmetric, transient heat conduction equation, and the evolutions of the melting temperature isotherm, which is referred to as the melt boundary in this study, are calculated to investigate the influences of the laser pulse shapes and intensity profiles on the hole geometry. This mathematical model provides a means of understanding the thermal effect of laser irradiation with different annular beam shapes. To take account of conduction in the solid, vaporization and convection due to the melt flow caused by an assist gas, an analytical two-dimensional model is developed for optical trepanning. The influences of pulse duration, laser pulse length, pulse repetition rate, intensity profiles and beam radius are investigated to examine their effects on the recast layer thickness, hole depth and taper. The ray tracing technique of geometrical optics is employed to design the necessary optics to transform a Gaussian laser beam into an annular beam of different intensity profiles. Such profiles include half Gaussian with maximum intensities at the inner and outer surfaces of the annulus, respectively, and full Gaussian with maximum intensity within the annulus. Two refractive arrangements have been presented in this study. Geometric optics, or ray optics, describes light propagation in terms of rays. However, it is a simplification of optics, and fails to account for many important optical effects such as diffraction and polarization. The diffractive behaviors of this optical trepanning system are stimulated and analyzed based on the Fresnel diffraction integral. Diffraction patterns of the resulting optical system are measured using a laser beam analyzer and compared with the theoretical results. Based on the theoretical and experimental results, the effects of experimental parameters are discussed. We have designed the annular beam shaping optical elements and the gas delivery system to construct an optical trepanning system. Laser drilling experiments are performed on the Stainless Steel-316 (SS 316) plate and the Inconel 718 (IN 718) plate. The geometry of the trepanning holes with different sizes is presented in this study.

The caving/sloughing of sandy layers into drilled shafts is a common and costly phenomenon in the drilling industry. A prototype soil-testing device known as the Pneumatic In-situ Soil Caving Index Sampler (PISCIS) has been developed to test sandy layers above the water table for their propensity to cave/slough into a drilled shaft during the drilling process. The PISCIS fits down a Cone Penetration Test (CPT) hole and uses air pressure to agitate a sample off of the hole wall that is then collected and weighed. Large-scale lab testing was conducted using sand under a variety of simulated overburden pressures and fines contents. The tests were conducted with a dual purpose in mind. First, the tests confirmed the functionality of the PISCIS prototype and its ability to collect samples in a consistent and repeatable manner. Second, the tests resulted in a calibration curve that shows a very strong (nearly exponential) relationship between collected sample weight and the fines content of the test sand; higher fines contents resulted in lower collection weights. The PISCIS was designed to supplement information found in a geotechnical report with information that would specifically inform drilling contractors about potential caving/sloughing hazards found in the stratigraphy.

Drilling and blasting procedures are a critical part of mine planning activities and improvements in this stage can lead to better productivity downstream and lower costs. One potential improvement would be better understanding the characteristics of the rock for blast design purposes. The distribution of material properties within a rock mass is very unpredictable so to more accurately determine its characteristics a controlled drilling environment is needed. Many mines possess the capacity to record Measurement While Drilling (MWD) data but don't utilize it. This project investigates and analyzes MWD data from an anonymous iron ore mine. Machine learning was used to analyze the MWD data for the sake of improving blast optimization and productivity and has been used to successfully implement MWD data in other studies. Based on previous work, it has been demonstrated that the utilization of MWD data can assist with developing a better understanding of rock mass properties and other variables of importance during the drill, blast, and mine planning processes. This report investigates using MWD data to classify and predict lithology and utilize regression modeling to identify potential soft spots within blast patterns for blast optimization. The MWD data of six blast patterns from an anonymous mine underwent data processing and then were modeled. The lithology was able to be approximately classified with new information of potentially revealed bed boundaries and blast pattern soft spots. / Master of Science / In the mining industry, liberating ore from the ground is necessary to process the material and generate products. To accomplish this liberation objective a process of drilling and blasting is utilized. A pattern is designed, and holes are drilled that match the spacing and depth of the design. The blast holes are loaded with explosives and detonated to create fractured rock for the liberation of desired material. During the drilling process, drilling parameters are recorded called Measure While Drilling (MWD) data. Previous research has demonstrated that modeling techniques using MWD data can assist with developing a better understanding of rock mass properties and other variables of importance during the drill, blast, and mine planning processes. Utilizing MWD data and machine learning to improve blasting procedures by classifying and predicting bed assignment and potential soft spots in a blast hole will be investigated in this research. The MWD data comes from 6 blast patterns from an anonymous iron ore mine. After the data was processed and modeled the lithology was classified with a validation accuracy of approximately 78% and potential soft spots estimated.

Coalbed methane wells have been used for many years as a viable means of extracting quantities of methane gas for use as a clean and efficient energy source. However, there is a limited understanding of many of the factors involved during the extraction process. As the more easily attainable reservoirs are depleted, it is imperative to gain a greater comprehension of these factors in order to develop techniques to efficiently collect economical quantities of methane gas in the future. For this investigation, an extensive database was compiled, consisting of a large set of parameters pertaining to the development of coalbed methane gas wells. Using the information contained in this database, a statistical analysis was performed in order to gain a better understanding of the relationships between the many factors involved in extracting quantities of methane gas from the ground. The results of this analysis showed that the majority of the parameters shown to have the greatest impact on methane production were heavily dependent upon the geology of the region. As a result, any attempt to exploit them for optimization exercises would be extremely difficult. Of the parameters shown to have the least dependence on naturally occurring phenomena, the amount of proppant sand used to hold fractures open within the well system after stimulation was shown to have the most impact During the well stimulation procedure, the proppant sand is carried into the fractures in the strata by a foam fracturing fluid. The sand acts to support the fracture system, increasing the permeability of formation, and allowing the methane gas to flow to the wellbore. By treating the sand particles with certain reagents, it is possible to render them hydrophobic, making it possible for them to stick to the bubbles within the foam and be carried deeper into the formation. Results of an investigation of sands treated to different degrees of hydrophobicity have shown that such treatments significantly increase the amount of sand distributed over a greater distance. / Master of Science

<p> Burr formation is a frequent problem in metal cutting. Burrs, which are defined as undesired projections of material resulting from plastic deformation, affect the precision of machined components and can negatively affect the assembly process. One common burr is the exit burr that forms when drilling ductile materials such as aluminum alloy. Deburring, the process of removing burrs, can account for up to 30% of the total production cost. If the burr size can be reduced, the deburring effort can also be reduced or even eliminated, resulting in an improvement in productivity and an increase in profit. </p> <p> There are different methods to reduce burr formation in drilling. One method is known as vibration assisted drilling. Vibration assisted drilling has been reported as an effective method to reduce burr height without reducing the material removal rate or permanently altering the mechanical behavior of the workpiece material. Other reported benefits of vibration assisted drilling include improvement of tool life and better machined surface quality. However, it has been reported that poor choice of vibration conditions (frequency and amplitude) can increase burr height. No accurate analytical model exists in the current literature that can predict the exit burr height for vibration assisted drilling. To predict exit burr height, a model capable of predicting thrust force accurately is important because higher thrust force produces larger exit burr. Clearly there is a need to develop these models. </p> <p> This thesis presents the development of analytical models for predicting thrust force and exit burr height for vibration assisted drilling of aluminum 6061-T6. The developed models incorporate all significant characteristics of vibration assisted drilling to achieve accurate predictions. Drilling experiments were performed over a range of cutting and vibration conditions. The experimental results demonstrate that the developed thrust force model improves the accuracy by up to 45% in comparison to the existing vibration assisted drilling models. The developed burr height model accurately predicts the exit burr height for vibration assisted drilling, with an averaged deviation of 10% from the experimental results. The developed models are also applicable to conventional drilling. Comparing with the existing drilling models, the new models improve the accuracy of thrust force and burr height predictions by 6 and 36% respectively. A fast analytical method has also been developed that predicts the favourable vibration conditions that minimize burr height. The predictions obtained using this method are consistent with the experimental results. Drilling experiments for combined frequency vibration assisted drilling were also performed over a range of vibration conditions. The experimental results demonstrate that combining two different favourable vibration conditions together produces greater mean thrust force reduction than using a single frequency vibration assistance. </p> / Thesis / Doctor of Philosophy (PhD)

<p> The movement of diamond drills by tracked vehicles and drill trailers in south Central Keewatin was studied during the summer of 1980. Tests of the physical ground strength showed that the ability of the terrain to resist disturbance from tracked vehicle operations depended on two main physical factors: the type of surficial material and the presence of water. Moisture contents varied throughout the summer so that the response of till and peat to compression and shear was not constant. As the summer proqressed, the increasing depth of thaw and gradual surface drying caused strengthening of both major types of surficial material. As a result, vehicle trafficability gradually increased throughout the summer. While surface rutting increased the depth of thaw compared to an undisturbed site, especially in peat, after the first few weeks of the thaw this had little apparent effect on vehicle trafficability. In many cases the vehicle disturbance was largely aesthetic giving the impression that the terrain disturbance was much more serious than it actually was.</p> <p> Although the load distribution of the vehicle tracks concentrated much of the longitudinal stress directly beneath the bogie wheels, in most cases the performance of the tracked vehicle itself was adequate. However, problems caused by the drill trailer wheels resulted in unnecessary mechanical strain on the vehicles and created marked increases in terrain disturbance.</p> / Thesis / Bachelor of Arts (BA)

The method of percussive rotary drilling is recognized as the most efficient method for hard rock drilling. Despite the clear advantages over conventional rotary meth-ods, there are still uncertainties associated with percussive rotary drilling. For geothermal applications, it is estimated that 50 % of the total cost per installed megawatt of energy is associated with drilling and well construction, with drill bit wear being a predominant cost factor. Numerical modelling and simulation of rock drilling, calibrated and validated towards rigorous experiments, can give insight into the rock drilling process. This thesis is focused on the prerequisites of numer-ical simulations of rock drilling, i.e. the development of a numerical model and experimental characterization of rock materials. A new approach for modelling brittle heterogeneous materials was developed in this work. The model is based on the Bonded Particle Method (BPM) for the Discrete Element Method (DEM), where heterogeneity is introduced in two ways. Firstly, the material grains are rep-resented by random, irregular ellipsoids that are distributed throughout the body. Secondly, these grains are constructed using the BPM-DEM approach with mi-cromechanical parameters governed by the Weibull distribution. The model was applied to the Brazilian Disc Test (BDT), where crack initiation, propagation, coalescence and branching could be investigated for different levels of heterogene-ity and intergranular cement strengths. The initiation and propagation of the cracks were found to be highly dependent on the level of heterogeneity and cement strengths. In the experimental study, the static and dynamic properties of two rock materials - Kuru grey granite and Kuru black diorite - were obtained from uniaxial compression and indirect tension tests. A Split-Hopkinson Pressure Bar was used to obtain the dynamic properties. Using high-speed photography with frame rate 663,000 fps, the crack initiation and propagation could be studied in de-tail, and the full-field exterior deformation fields of the samples were evaluated by using digital image correlation. From the high-speed images, the onset of unstable crack growth was detected. The crack-damage stresses, associated with unstable crack growth, was approx. 90 % of the peak strength in the dynamic compression tests, whereas the tensile crack-damage stress was approx 70 % of the tensile peak strength.

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