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Prasad, Umesh. "Energy utilisation in comminution and its application to rock blasting." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26412.
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Since blasting is a comminution process, the feasibility of establishing a correlation between the Bond rod mill work index (kWh/t) and some easily measurable physico-mechanical properties relevant to blasting was investigated. Further, the concept of operating blast work index and its potential applications were explored. Four different rock types and a well documented case study of two blasts were selected for this study.The work index is found to be uncorrelated with the density and unconfined compressive strength, slightly related with tensile strength, and well correlated with dynamic rock properties, especially the P-wave velocity and the bulk modulus. The standard deviation in measured compressive and tensile strength values is found to be very high, compared to their seismic and dynamic elastic properties.
The case study encompassed two blasts with identical blast-patterns and rock type consuming almost the same amount of explosive (kg/t) but with very different specific blast energies (MJ/t). The agreement between operating work index of the two blasts (13.4 kWh/t vs. 13.1 kWh/t) and laboratory work index (17.0 kWh/t) was modest (within 30%). The operating work index corresponding to either blast has been used to predict the product size (P$ sb{80}$) of the other. The choice of feed size (F$ sb{80}$) was discussed; whereas the previous researchers had used the theoretical value of infinity, the use of much smaller value, the average of effective burden and spacing, was proposed. This concept is used in a proposed method to estimate blasting energy requirements as a function of blast geometry, rock type and desired product size. Future test work that would provide a data base and validation for this concept is described.
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Garvey, Ryan J. "A study of unstable rock failures using finite difference and discrete element methods." Thesis, Colorado School of Mines, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3557944.
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Case histories in mining have long described pillars or faces of rock failing violently with an accompanying rapid ejection of debris and broken material into the working areas of the mine. These unstable failures have resulted in large losses of life and collapses of entire mine panels. Modern mining operations take significant steps to reduce the likelihood of unstable failure, however eliminating their occurrence is difficult in practice. Researchers over several decades have supplemented studies of unstable failures through the application of various numerical methods. The direction of the current research is to extend these methods and to develop improved numerical tools with which to study unstable failures in underground mining layouts.
An extensive study is first conducted on the expression of unstable failure in discrete element and finite difference methods. Simulated uniaxial compressive strength tests are run on brittle rock specimens. Stable or unstable loading conditions are applied onto the brittle specimens by a pair of elastic platens with ranging stiffnesses. Determinations of instability are established through stress and strain histories taken for the specimen and the system.
Additional numerical tools are then developed for the finite difference method to analyze unstable failure in larger mine models. Instability identifiers are established for assessing the locations and relative magnitudes of unstable failure through measures of rapid dynamic motion. An energy balance is developed which calculates the excess energy released as a result of unstable equilibria in rock systems. These tools are validated through uniaxial and triaxial compressive strength tests and are extended to models of coal pillars and a simplified mining layout.
The results of the finite difference simulations reveal that the instability identifiers and excess energy calculations provide a generalized methodology for assessing unstable failures within potentially complex mine models. These combined numerical tools may be applied in future studies to design primary and secondary supports in bump-prone conditions, evaluate retreat mining cut sequences, asses pillar de-stressing techniques, or perform backanalyses on unstable failures in select mining layouts.
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Drescher, Karsten. "An investigation into the mechanisms of time dependent deformation of hard rocks." Pretoria : [s.n.], 2002. http://upetd.up.ac.za/thesis/available/etd-07082005-141037/.
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Simon, Richard 1967. "Analysis of fault-slip mechanisms in hard rock mining." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35945.
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Rockbursts may cause damages to underground openings and to equipment, and constitute a major hazard to the safety of mine workers. One method that can be used to evaluate if there is a rockburst potential is to compare the stiffness of the failed rock with that of the surrounding rock mass. This method has been applied successfully in the past to rockbursts involving fracturing of the rock mass.This thesis deals with the development of a similar approach for rockbursts involving a violent slip along major geological discontinuities. To evaluate the post-peak shear stiffness of a discontinuity, a new non-linear constitutive model for rock joint was developed. This model is based on two exponential formulations expressing the two phenomena taking part in the shearing process: friction resistance along surfaces and shearing of asperities. Compared with test results, the model showed a correlation factor (R2) of 0.90. The model was then implemented in an existing boundary element code to evaluate the interaction between underground openings and nearby geological discontinuities. Verification of the implementation was done by reproducing direct shear tests on a discontinuity. Parametric analyses were performed on the new model that highlighted the most important parameters. Methods to obtain the different stiffnesses involved in the violent slip process were developed. Examples of applications were given to illustrate the proposed methods.
Finally, an alternative method to evaluate the fault-slip rockburst potential was developed. This new method relies on a linear analysis and the calculation of a new index called the Out-of-Balance Index or OBI. The OBI showed some agreement with the stiffness approach.
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Stachulak, Jozef S. "Controlled air recirculation consideration for Canadian hard rock mining." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39523.
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Recirculation of air is a widely used technique in general ventilation and air conditioning practise.Interest in the application of controlled recirculation of ventilation air in mines has grown considerably in the last decade. This is evident by the number of controlled recirculation schemes which have been implemented or are being considered or planned in several countries and in different types of mines.
A detailed description is given of the operating and proposed schemes in South African gold and U.K. coal mines. This includes safety, dust filtration and blast contaminant removal systems.
The monitoring and feasibility methodology required to evaluate controlled recirculation for heat reclamation, and thus cost saving, in Canadian hard rock mines, is then examined.
Experimental work pertaining to air quality study, carried out at three mines, is described in detail, and backed up by extensive appendices.
The observed deposition of dust and reduction in gaseous pollutants concentration in exhaust shafts are analyzed and depicted in several figures and tables.
Simplified theoretical aspects of dust deposition, and statistical analysis of the obtained results, are outlined.
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Satish, Hemanth. "Exploring microwave assisted rock breakage for possible space mining applications." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83932.
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As humanity prepares to migrate to the frontiers of the Moon and other planets, the area of mining in space must go along for the purpose of exploration and in-situ resource utilization. In the present work the literature that has been developed over the years in the area of mining in space as applicable to Lunar and Martian environments is reviewed. Subsequently, the key mining technologies that are most suitable for Lunar and Martian environments are identified. From the literature review, it is concluded that an optimal combination of both mechanical methods and novel energy (lasers, microwaves, nuclear energy) methods for rock destruction drawing a trade off between the energy and mass would be the most ideal option for space applications.One such technique of applying low power microwaves to the rocks to thermally weaken them without actually melting them before employing mechanical methods of rock destruction is investigated. Finite element simulations were carried out to simulate microwave heating of a calcareous rock to determine the temperature profiles and thermal stresses at different microwave heating times and powers. Preliminary experiments were carried out in order to determine the microwave susceptibility of terrestrial basalt (which has similar composition as Lunar and Martian rocks). Temperature and strength of the rock sample before and after microwaving was measured.
The results of the finite element simulation indicated that a calcareous rock with microwave responsive phase and a microwave non-responsive phase developed thermal stresses of large magnitudes exceeding the actual strength of the rock. The simulation methodology can be applied to other rock types as well, provided the thermal, electrical and structural properties of constituent mineral phases are available.
The preliminary experimental results showed that the basalt rock specimens used were quite susceptible to the low power microwaves. There was a decreasing trend in terms of the point load index of the rock samples as the microwaving exposure times were increased, with some rock samples showing visible cracks at higher microwaving times.
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Wu, Long. "A study on automatic control of wheel loaders in rock/soil loading." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289916.
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Wheel loaders are widely used in mines, construction projects, and waste processing fields due to their merits of high mobility, remarkable operational flexibility, and relative low capital cost. Automatic control of the loading process will achieve high productivity, solve the problem of shortage of experienced operators, release human workers from hazardous working environments, and reduce maintenance cost associated with machine abuse. Existing research on wheel loader control only automate the manipulator mechanism while leave the locomotion system to human operators. The research in this dissertation focuses on the development of a digging controller that can simultaneously control bucket motion and vehicle advancement, and can adapt its parameters in different digging conditions. In this controller, a digging task is decomposed into three sequentially implemented operations: attacking, crowding, and scooping; each of them can be carried out with different strategies. An ideal trajectory is pre-generated based on the physical property of the wheel loader and rock pile, and is generally followed during the digging process. Human operators' practice in regulating vehicle speed and coordinating bucket motion and vehicle advancement is intensively investigated, refined into control rules, and implemented with intelligent and conventional control methods. Machine features are analyzed in depth and incorporated into control algorithm design. The investigation on the non-trivial time-delay characteristic of the manipulator hydraulic system leads to the building of dynamic models and the application of predictive control principle in digging decision-making. The feature of small working space of wheel loader was considered in bucket trajectory generation and instant bucket motion planning. The research on wheel slip occurrence leads to a detection algorithm being developed and a slip restrain strategy being presented. Self-adaptation mechanism is constructed in which trajectory tracking-quality is applied for evaluating digging control performance, statistical analysis is applied for improving the accuracy on bucket penetration depth prediction, and machine-learning technique is applied for revising the membership function of fuzzy consequent variables. Simulation experiments show that the controller works effectively in rock piles with different conditions, from fine sand and soil to big fragmented rock pieces.
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Roth, Karen. "Time-Dependent Rock Failure at Kartchner Caverns, Arizona." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613408.
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Assessing long-term rock stability is an important aspect in the analysis of slopes, dam and bridge foundations, and other infrastructure. Rock behavior over tens to thousands of years must be anticipated when predicting the performance of, for example, an underground containment facility for nuclear waste. At such long time scales, the time dependence of rock failure, typically ignored in short time scale analyses, has a significant effect and must be included in the analysis. Since time-dependent rock behavior is thought to be caused by the subcritical growth of microcracks, a time-dependent analysis should incorporate a method of simulating subcritical crack growth. In this thesis, a rock bridge damage model was developed using the finite element program Abaqus to simulate subcritical crack growth for all three modes of crack tip displacement in three-dimensional rock masses. Since subcritical crack growth is not among the damage initiation and evolution criteria available in Abaqus, its effect was included in the model through the USDFLD user subroutine. Material properties for the damage model were obtained through laboratory fracture toughness testing of Escabrosa limestone from Kartchner Caverns. Tests included the grooved disk test for mode I, the punch-through shear with confining pressure test for mode II, and the circumferentially-notched cylindrical specimen test for mode III. The subcritical crack growth parameters n and A were calculated for all three modes using the constant stress-rate method. Fracture test results were compared with a previous study by Tae Young Ko at the University of Arizona, which tested Coconino sandstone and determined that the subcritical crack growth parameters were consistent among modes. This thesis expands upon Ko's work by adding the characterization of a second rock material in all three modes; results indicate that for Escabrosa limestone the subcritical crack growth parameters are not consistent among modes. Additionally, the Escabrosa limestone composing the caverns ranges from a more homogeneous, even-grained texture to a more heterogeneous texture consisting of coarse-grained veins and solution cavities set in a fine-grained matrix. To determine if the veined regions are more susceptible to fracturing and act as the nuclei of rock bridge failure, the fracture toughness tests were conducted separately for each texture. Results indicate that the more heterogeneous limestone has a higher fracture strength, fracture toughness, and subcritical crack growth index n than the more homogeneous limestone. This is in agreement with previous studies that determined that a more complex and heterogeneous microstructure produces a larger microcrack process zone and a more tortuous crack path, leading to higher fracture energies and larger values of n. Application of the rock bridge damage model to a simplified Kartchner cave room with a single roof block provided visualization of decreasing rock bridge size and produced time-to-failure estimates of 1,251 to 65,850 years. Multiple models were run to study the effect of (i) using material properties from each of the two textures identified in the Escabrosa limestone and (ii) varying the in-situ stress ratio, K. Both the value of K and the choice of Escabrosa texture had a large effect on the estimated time-to-failure, indicating that for future modeling of Kartchner accurate estimation of the in-situ stress ratio is as important as field identification of homogeneous vs. heterogeneous textures.
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Mahony, Luke T. School of Mining UNSW. "Development of a laboratory facility for testing shear performance of installed rock reinforcement elements." Awarded by:University of New South Wales. School of Mining, 2006. http://handle.unsw.edu.au/1959.4/25700.
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Rock reinforcing elements provide a significant proportion of their ground control capability through offering resistance to shear movement of adjacent rock masses or blocks. This potential shear movement may take the form of sliding on horizontal bedding planes leading to strata bending; or block displacement along other geological structures such as joints or similar discontinuities. Much has been reported about this type of behaviour of rock bolts and other tendons, in theoretical concepts. However, there is a shortage of quality data available on the exact nature of this mechanism for shear resistance, and the role played by parameters such as pre-tensioning. A clearer understanding of the nature and significance of this type of behaviour has major implications for rock reinforcing materials and installation design. This thesis, which was supported by the Australian Coal Research Program (ACARP) describes the design, construction and commissioning of a laboratory testing facility at the School of Mining Engineering, University of New South Wales (UNSW), Australia and a subsequent testing program. The single failure plane design adopted in the test rig has been successful in allowing shear loading to be directly applied to fully installed rockbolts. Rockbolts were installed into an offset concrete rockmass, which consisted of two separate concrete samples that created a smooth shear plane surface. The reinforced samples were subjected to an applied shear load and critical parameters such as load and shear displacement were recorded. Influencing parameters such as concrete strength and applied pre-tension were altered and recorded to determine their effects on the overall shear performance of the sample. The failure mode of the rockbolts was also examined. The results indicate that a relative stronger rockmass material caused the rockbolt to fail within a lower shear displacement compared to a relatively weaker material. Also, a pre-tensioned rockbolt tended to resist shear displacement at least initially, until high shear loads developed. This phenomena is beneficial to ground support as less movement would tend to maintain integral strength of the rockmass. The use of strain-gauged rockbolts indicated as would be expected that the shear loading arrangement induced a compressive axial loading that tended to dissipate with distance from the shear surface.
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Shi, Xiaobo 1963. "Intelligent control of autonomous rock excavation: Theory and experimentation." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282264.
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Earthmoving is a common activity at mines, construction sites, hazardous waste cleanup locations, and road works. Expensive and sophisticated machines such as front-end-loaders (FEL), backhoe loaders, LHD loaders and front shovels are used for these excavation tasks. Autonomous excavation control for these machines has gained considerable attention in order to remove human operators from hazardous environments, improve productivity and utilization, reduce machine abuse, as well as decrease machine operating costs. However, automatic control of excavation tasks for many sites that require digging in rock cannot be implemented using existing factory-based automation techniques. For example, control of bucket motions by simply partitioning the terrain into a set of volumes where each equals the bucket capacity often does not work. Planning in this way is possible only when digging in the materials such as loose soils where bucket motion resistance through the media can be predicted. Resistance predictions are impossible and/or infeasible to generate for excavation in the environments which consists mainly of irregular rigid objects such as rock piles with oversized particles, since no means exists to predetermine subsurface bucket/material interactions that are required to preplan the bucket trajectory. As a result, bucket actions must be determined through on-line decision making based on sensory feedback of the current excavation status in the unpredictable, unstructured and dynamic rock excavation environment. This research proposes a control method for autonomous rock excavation. The control architecture is designed following the behavior-based control concept. That is, the rock excavation control problem is solved by decomposition of the complicated task into a variety of simple elements that can be implemented by excavation behaviors. However, this control approach presents a new structure and operational paradigm that is developed based on, but different from the traditional behavior control method. Here, the behaviors are chosen using fuzzy excavation situation assessment with guidance of excavation task planning which embodies excavation heuristics and human strategies. Task plans are formulated using finite state machines which integrate neural networks for decision making. This organizational structure has the capability to include more excavation goals and to adapt to different environments via learning. Excavation behaviors are performed by primitive and machine executable actions or action sequences structured using finite state machines and simple action arbitration rules. The actions of human FEL operators were observed and analyzed to extract basic bucket actions and define rules of arbitration for different actions or action sequences under particular excavation environments. Fuzzy logic is applied to implement each excavation action where fuzzy rules represent the human experience and heuristics that are intrinsically linguistic, and bucket excavation motions are evaluated based on insufficient and inaccurate input sensory data. A variety of experiments were performed to test the ability of the proposed control algorithm. The laboratory-based experimental autonomous excavation system consists of a robotic arm, an excavation testbed, a force/torque sensor mounted between the robot arm wrist and the excavation bucket, and a control computer. Various rock piles to simulate realistic excavation environments and conditions were generated in the testbed. With these experiments, the control algorithm has demonstrated the ability to execute real-time automated loading cycles effectively and efficiently in complex excavation environments and under difficult digging conditions, through the use of the flexible excavation behaviors.
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Hudyma, Martin Raymond. "Analysis and interpretation of clusters of seismic events in mines." University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0054.
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Spatial clustering of seismic events in mines has been widely reported in literature. Despite obvious visual correlations between spatial clusters of seismic events and geomechanical structures in mines (such as pillars, dykes and faults), very limited research has been undertaken to utilise this information to filter seismic data. A linkage between spatial seismic event clusters and discrete rockmass failure mechanisms is tenuous and not well established using current seismic analysis techniques. A seismic event clustering methodology is proposed. The first component of the methodology uses a complete-linkage (CLINK) clustering routine to identify relatively compact clusters of seismic events. The CLINK clusters are then subjected to a singlelink clustering process, which uses spatial location and seismic source parameters as similarity measures. The resultant
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Becker, James B. "A Combined Field, Laboratory, and Numerical Study of Cutter Roof Failure inCarroll Hollow Mine, Carroll County, Ohio." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366382367.
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Rentzelos, Theofanis. "Numerical Investigation of Rock Support Arches." Thesis, Luleå tekniska universitet, Geoteknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76698.
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The Garpenberg mine, owned by the Boliden Mining group, has established a trial area at Dammsjön orebody in order to examine the possibility of increasing the productivity of the mine. The mine uses the rill mining method with a current rill height of 15 m. In order to increase the productivity, the mine is examining the possibility of increasing the height of the rill. The trial area is located at 882 m depth surrounded by dolomite on the hangingwall and quartzitic rock on the footwall side. Rock support arches have been installed, in addition to the regular support pattern, to test their effectiveness on stabilizing the ground around the drifts. The arches have been installed in every 6 m and every 3 m in different parts of the test area. Rock samples from the trial area were brought to the university laboratory for testing. The data gathered from the laboratory tests along with the data from the monitoring of the trial area were used to develop a calibrated numerical model. A three-dimensional (3-D) model was therefore created, by using the FLAC3D numerical code. After the calibration of the model a parametric study was conducted for different rill heights and different arch spacing to investigate the performance of the arches. Specifically, the case of no arch installation along with the cases of an installed arch every 6 m and 3 m were tested, for the rill heights of 15 m, 20 m, 25 m and 30 m. The study concluded that the arches assisted in reducing the ground convergence in the production drift. The results also showed that the total height of the rill bench yields regardless of its height. After the yielding, the rockmass can no longer support itself and caves under its own weight. The larger the rill height, the larger the volume of loose rock that has to be supported and thus, higher the convergence. Furthermore, it was also observed that, significant amount of convergence in the production drift occurred during the drifting of the top drive and less during the stoping of the rill bench. This indicates that, the timely installation of the arches is an important criterion for their performance.
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Andersson, J. Christer. "Rock Mass Response to Coupled Mechanical Thermal Loading : Äspö Pillar Stability Experiment, Sweden." Doctoral thesis, KTH, Jord- och bergmekanik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4287.
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The geological disposal of nuclear waste, in underground openings and the long-term performance of these openings demand a detailed understanding of fundamental rock mechanics. A full scale field experiment: Äspö Pillar Stability Experiment was conducted at a depth of 450 m in sparsely fractured granitic rock to examine the rock mass response between two deposition holes. An oval shaped tunnel was excavated parallel to the σ3 direction to provide access to the experiment and also provide elevated stress magnitudes in the floor. In the tunnel floor two 1.75-m diameter 6-m deep boreholes were excavated so that a 1-m thick pillar was created between them. In one of the holes a confinement pressure of 700 kPa was applied and in the other displacement transducers were installed. The pillar volume was monitored by an Acoustic Emission System. Spatially distributed thermocouples were used to monitor the temperature development as the pillar was heated by electrical heaters. The excavation-induced stress together with the thermal-induced stress was sufficient to cause the wall of the open borehole to yield. The temperature-induced stress was increased slowly to enable detailed studies of the rock mass yielding process. Once the rock mass loading response was observed, the rock mass was unloaded using a de-stress slotting technique. This thesis focuses on the in-situ study of the rock mass response to coupled mechanical thermal loading and thermal-mechanical unloading. The experiment, its design, monitoring and observations are thoroughly described. An estimate of the yielding strength of the rock mass is presented and compared with laboratory test and results from other rock mass conditions reported elsewhere in the open literature. General conclusions about the effect of the confining pressure and the observations from the unloading of the pillar are also presented. Important findings are that the yielding strength of the rock mass has been successfully determined, low confinement pressures significantly affects the onset of yielding, the primary mode of fracture initiation and propagation is extensional, no significant time dependency of the yielding process was observed. The unloading studies also indicated that what appeared to be shear bands likely was a propagating zone of extensile failure that weakened the rock so that displacements in the shear direction could occur.QC 20100622
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Rikberg, Heidi. "Field damage investigation and evaluation of numerical model using the collected data at Kemi Mine." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-73114.
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This Master´s Thesis studies the applicability of existing numerical model to predict the conditions in the drifts at the mine. Damage mapping, covering the existing production levels, has been carried out to study the condition of the surface support, i.e. shotcrete, mesh and rock bolts to quantify the amount of deformation visible in the tunnels. Irregularities in the floor levels were also mapped. The rock support applied varies between different areas, from only a layer of shotcrete to areas where shotcrete, mesh and cable bolts are applied sequentially. The large amount of support in some regions is required because of high in situ rock stresses in Kemi Mine. The geological conditions are challenging, with large local variation making efficient supporting and damage prediction difficult. Access drifts at the mine have varying service times, on average 6 years, which is a long time in a difficult environment. The results from this work are a mine specific damage classification, used in the mapping to capture the range of damages seen on site. A reoccurrence of same areas showing damages on several production levels is noted. Digitized versions of the damage maps were made and these have been compared to simulation results. The comparisons were made to plots of deviatoric strain, deviatoric stress and total displacement. Based on the work done during this project it can be concluded that the studied parameters have varying levels of agreement with the drifts, both when comparing the levels with each other and the results in the same level between spring and autumn. The best agreement is found with the deviatoric strain increment and the yielded elements. Rock mechanics and geological reasons for the variations seen between the mapping results and the simulations results can be further studied in the future, as can the alternatives for increasing the accuracy through changes in the numerical model or model type used for comparison.
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Ghosh, Rajib. "Assessment of rock mass quality and its effects on charge ability using drill monitoring technique." Doctoral thesis, Luleå tekniska universitet, Geoteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65584.
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Terezopoulos, N. G. "Rock mechanics design principles applied to tunnel stability in deep mining conditions." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373790.
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Mawdesley, Clare A. "Predicting rock mass cavability in block caving mines /." St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16404.pdf.
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Nejati, Houshin. "Analysis of physical properties and thermo – mechanical induced fractures of rocks subjected to microwave radiation." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123156.
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This doctoral thesis investigates the microwave heating process, and its influence upon the physical properties and propagation of fractures in Rocks Under Illumination (RUI).In order to best understand microwave-assisted rock fracturing, it is critical to investigate the different aspects of this process. These range from the electromagnetic study (i.e., dielectric heating and heat generation), to the mechanical aspects (i.e., heat transfer, strength reduction material mechanics and fracture mechanics), and finally to the final fracturing behaviour of RUIs (i.e., fractography). In order to understand the various elements of the microwave fracturing of rocks, this research is divided into three investigations: 1) An investigation of the magnitude of heat generation within a rock body, and the extent to which illumination parameters can influence the efficiency of a microwave rock fracturing system. In addition, this research sought to expand the scope of microwave rock fracturing beyond the basaltic rocks utilized, and to apply this technique to other rock samples. This research investigates the possibility of substantially reducing the required energy input for a microwave-assisted rock fracturing system. This is made possible when operating at the optimal illumination parameters, with regard to each material property of the rock. To study the microwave heating process of rocks over a wide frequency range, the dielectric properties of some rocks are measured over frequencies ranging from 200 MHz to 20 GHz; with various water content, from fully dried to fully saturated; and at elevated temperatures ranging from 23ºC to 80oC.2) An investigation of the mechanical aspects of microwaves. This study sought to evaluate the influence of microwave illumination properties (i.e., input microwave power and exposure duration) on the fracture toughness of basalt samples and fracturing. It also attempted to experimentally quantify the fracture strength reduction of Chinese basalt after microwave illumination, at a variety of power levels and durations of exposure. Finally, the investigation sought to evaluate any correlation between the density of micro-cracks caused by microwave heating and any reduction in fracture toughness. This correlation was then modeled with the aid of numerical modeling (i.e., Discrete Element Modeling).3) A quantitative and qualitative investigation of the fracture development of Basalt Specimens Under Microwave Illuminations (BSUI) at macroscopic and microscopic scales. This research describes results of the visual investigations of the Fracture Growth Path (FGP) and the fracturing behaviour of SCBs after being exposed to microwave illuminations. FGPs are classified via their surface temperature level and the required input of microwave power. The Petrography Standard Test aided this approach, and allowed me to best describe fracture behaviour and the interactions between the fractures and mineralogical composition of Chinese basalt. A comprehensive fractographic investigation using Scanning Electron Microscopy (SEM) investigated microwave induced fracturing (i.e., fracture morphologies, fracture behaviours and the interaction of micro-fractures with rock forming minerals) in Chinese basalt fracture surfaces.Microwaves rock fracturing has potential to be employed for space applications: In Situ Resource Utilization (ISRU), sampling and In Situ material analysis sampling, in addition to mining and full face tunnelling applications on earth.Cette thèse de doctorat examine le procédé de chauffage par micro-ondes, et son influence sur les propriétés physiques et la propagation de fractures de roche sous illumination micro-onde (RUI). Pour bien comprendre la fracturation de roche avec assistance d'illumination micro-onde, il est essentiel de se pencher sur différents aspects du procédé. Ceux-ci vont de l'étude électromagnétique (chauffage diélectrique et génération de chaleur), jusqu'aux aspects mécaniques (transfère de chaleur, réduction de la résistance mécanique, mécanique de fracturation), et finalement jusqu'au comportement de fracturation final de la roche sous illumination micro-onde (fractographie). En tout, l'étude est divisée en trois parties :1) Une étude sur la magnitude de la génération de chaleur dans un corps rocheux, et dans quelle mesure les paramètres de l'illumination micro-ondes peut influencer l'efficacité d'un système de fracturation de roche avec chauffage par micro-ondes. Cette recherche tente d'élargir l'utilisation de chauffage par micro-ondes au-delà des roches basaltiques en appliquant cette technique à d'autres spécimens de roche. Cette recherche étudie aussi la possibilité de réduire substantiellement l'énergie d'entrée requise pour un système de fracturation de roche avec chauffage par micro-ondes. Ceci est possible lorsque les paramètres d'illumination micro-ondes sont optimisés par rapport aux propriétés de la roche. Pour étudier le processus de chauffage par micro-ondes à travers une ample gamme de fréquences, les propriétés diélectriques de plusieurs roches sont mesurées entre des fréquences de 200MHz à 20GHz. Le contenu d'eau varie entre parfaitement séché et complètement saturé, et la température varie entre la température de la pièce et 80oC.2) Une étude des aspects mécaniques des micro-ondes. Cette étude tente d'évaluer l'influence des propriétés de l'illumination micro-onde (puissance d'entrée micro-onde, durée d'exposition) sur la résistance de rupture de spécimens de basalte. L'étude tente aussi de quantifier expérimentalement la réduction de la résistance de rupture de spécimens de basalte chinois après l'illumination aux micro-ondes, en variant la puissance d'illumination ainsi que la durée d'exposition. Finalement, l'étude cherche à évaluer la corrélation entre la densité des micro-fractures causées par le chauffage par micro-ondes et la réduction de la résistance de rupture de la roche. La corrélation est ensuite modélisée à l'aide de modélisation numérique.3) Une étude qualitative et quantitative du développent de fractures dans des spécimens de basalte sous illumination micro-onde à l'échelle macroscopique et microscopique. Cette recherche décrit les résultats the l'étude visuelle du chemin de rupture (FGP) et le comportement de fracturation des SCBs après l'illumination par micro-ondes. Les FGP sont classifiés par rapport à la température de surface et la puissance d'entrée de micro-ondes requise. Le test standard de pétrographie aide à cette approche, et permet de mieux décrire le comportement de fracturation, et l'interaction entre les fractures et la composition minéralogique du basalte chinois. Une étude fractographique compréhensive sur la surface des ruptures induites dans le basalte chinois par l'illumination micro-onde (morphologie de rupture, comportement de rupture) est conduite en utilisant un microscope électronique à balayage (MEB). Cette recherche discute la possibilité d'utiliser les micro-ondes pour des applications spatiales : l'utilisation de ressources in-situ, l'échantillonnage et l'analyse d'échantillons in-situ, ainsi que des applications sur terre tel que l'extraction minière et la construction de tunnels.
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Sharpe, Colin James 1962. "Experimental effectiveness of rock fracture grouting." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/291736.
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The objective of this investigation is to experimentally determine the effectiveness of fracture sealing in welded tuff using ordinary portland cement and microfine cement grouts. Fracture grouting will most likely be used to seal fractures intersecting high level nuclear waste repositories. Fractures are potential pathways for the migration of radionuclides. Laboratory experiments have been performed on seventeen tuff cylinders. (1) tension induced cracks, (2) natural and, (3) sawcut surfaces serve as fractures. Prior to grouting, the hydraulic conductivity of the intact rock and that of the fractures themselves are measured under a range of normal stresses. Grouts are injected through axial boreholes at pressures of 0.3 to 4.1 MPa while holding fractures under a constant normal stress. Five grout formulations have been selected. Minor amounts of bentonite (0 to 5 percent by weight) have been added to these grouts to increase stability. Water to cement ratios range from 0.45 to 1.0. Permeameter testing of grouted fractures is used to evaluate the effectiveness of fracture grouting.
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Xiao, G. C. "Rock engineering investigations for North Selby shaft insets." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376322.
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Rogers, Gary K. "The stability of portals in rock." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54405.
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Portals are frequently an exceedingly difficult area in terms of ground control due to the near-surface, weathered, and highly discontinuous rock mass conditions. Surface and subsurface failures involving portals were analyzed using over 500 case histories which were organized into a database. Critical factors contributing to both stability and instability were isolated, and failures were classified according to location. Correlations between rock mass classes and types of portal failure were made and a four step stability analysis methodology defined. To determine critical sections of portal approach cuts for stability analysis, the Geomechanics Classification System was appended with discontinuity orientation adjustments. The most common type of failure for active portals, that of 'Crown Face Overbreak' failure, was investigated and modelled for design and support purposes. Results are confirmed using case study data. Excavation and support guidelines, based on database information the predicted failure zone from the 'Crown Face Overbreak' model are provided.Ph. D.
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Rizkalla, Maged Kamal. "Elasto-viscoplastic modelling of rock excavations." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60595.
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The first part of the thesis describes the concepts of viscoplasticity as a continuous plasticity theory highlighting different kinds of yield functions, plastic potentials and visocplastic constitutive laws.A 2-dimensional elasto-viscoplastic finite element model for stress/stability analysis of mining excavations has been developed for use on microcomputers. An iterative explicit time stepping scheme is implemented. The program uses automatic time-step calculator based on equations giving a limit on the time step in an attempt to prevent numerical instability when common forms of isotropic yield functions and plastic potentials are used in the viscoplastic solution. When the input data are read parallel to the analysis undertaken the user can simulate compound behaviour by stopping the analysis, examining the results graphically and restarting it again and possibly implementing a certain decision in the subsequent appended input. This also imposes no limit on the number of time stations at which instantaneous changes like elements cut, elements backfilled, loads added or simply outputs are required. The program is equipped with graphical pre- and post- processors.
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Cassapi, V. B. "Application of rock hardness and abrasive indexing to rock excavating equipment selection." Thesis, University of Nottingham, 1987. http://eprints.nottingham.ac.uk/14359/.
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The work carried out in this thesis outlines some of the problems associated with abrasive wear in machines and other mechanical equipment used to excavate or process natural rock material. It has been stated that if the problems associated with abrasion are to be better understood, then a sound knowledge of the abrasive potential of rocks is essential. A number of common wear mechanisms are described together with existing hardness and abrasive tests. The author has investigated rock hardness and abrasiveness by the use of existing methods and subsequently, developed new correlated with the well tests which can be established methods of determining physical and mechanical properties of rock. A project on hard rock drilling has been conducted to determine the rate of wear on expensive diamond impregnated coring drill bits. A detailed investigation which involved the design and manufacture of special measuring equipment to accurately measure and record changes in the profile shape of the bit during its life span. This has permitted a study of the wear characteristics related to the various drilling parameters employed. A collaborative project was carried out with DeBeers, UK, to attempt to discover methods of predicting the rate of specific wear on diamond impregnated saw blades and the cutting forces required with the sawing of hard stone materials. This project has led to a new statistical approach to the analysis of the acquired test data for this purpose. A number of case histories have been discussed and recommendations made. As a result of these investigations together with the work covered in this thesis, the author has developed two new abrasive tests. These tests can be used to test materials such as unconsolidated rocks which otherwise, could not be satisfactorily tested by the established tests already in existence. The new tests have been tried and proved by correlating the test data by combining multiple regression analysis with the results obtained from physical and petrological rock property tests with actual rock cutting data. Conclusions have been drawn and recommendations for future work suggested.
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Saharan, Mani Ram. "Dynamic modelling of rock fracturing by destress blasting." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84840.
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Rockburst control measures have been in practice with continued efforts for improvements since the beginning of the 20th century. The thesis concentrates on the evaluation of destress blasting, which is an important pro-active rockburst control measure. The concept of destress blasting is based on the fracturing of highly stressed rock mass by detonating explosive charge within it. The concept has been carried out ever since the first reported use in a Canadian coal mine circa the early 1930s. Since then, many mines across the continents have applied this technique using a trial-and-error approach with mixed successes. To date, the application lacks scientific base.The aim of this thesis is to identify the governing mechanisms associated with destress blasting applications. A holistic approach is undertaken, which involves a critical analysis of the reported field evidences, development of a numerical procedure and detailed investigations at the micro-mechanical level to investigate the fracturing of rock under confinement by different types and magnitudes of explosive energy.
A numerical procedure is developed in the thesis that carries promising potential to improve the understanding on rock fracturing by explosive energy as well as provides a platform to develop means for enhancing explosive energy utilization. The procedure is validated with reported field observations.
Analyses of destress blasting is made through dynamic modelling by simulating discrete fractures using the developed procedure. A normalized parameter ℓ ci is introduced to investigate fracturing extent after destress blasts. The investigations revealed that destress blasting produces limited fractures aligned along the principal stresses. The fracturing extent reduces with the increase in the confinement. The study indicates that the current practice of destress blasting seemingly provides more psychological benefits than factual benefits from the desired destressing.
The study also introduces a non-dimensional parameter, betaij , which characterizes destressing effects. The parameter not only adequately explains destressing phenomenon, but also offers clarifications to seemingly inexplicable reported field observations of destress blasting. Local fractures around the boreholes aligned along the principal stresses are found to be the cause of reported local stress concentration and rock stiffening post to destress blasting against the desired stress relaxation and softening.
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Vicenzi, Ivan Flaviano. "Numerical modelling of underground openings in bedded rock." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0035/MQ64251.pdf.
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Devgan, Ashutosh 1968. "Analysis of rock fragmentation using digital image processing." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278195.
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The success of rock fragmentation due to blasting depends on many variables, such as rock properties, in-situ fracturing, and blast design. Traditionally, the size distribution of fragmented rock particles has been determined through screen sieving. Modern techniques using video images and computer image processing techniques have the potential for analyzing rock fragmentation accurately and efficiently. A procedure has been developed for analyzing rock fragmentation which uses a high-resolution video camera for capturing images in the field, and specialized computer algorithms for processing these images. First of all, computer algorithms have been developed to delineate the individual rock fragments in the images. Secondly, a set of experiments have been conducted in the laboratory, in which the two dimensional information from the images is correlated with sieve results. Based on these experiments, a set of probabilities have been determined for correctly determining the size and volume of rock fragments from two dimensional images. Using these probabilities along with the particle delineation algorithm, the size distribution for the rock fragments is calculated. The computer algorithms can also combine information from many images to take into account sampling and images taken at different scales.
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Zahiri, Hani. "A predictive GIS methodology for mapping potential mining induced rock falls." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060725.120628/index.html.
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Akbarnejad, Nesheli Babak. "Rock mechanics aspects of blowout self-containment." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1835.
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Amjad, Muhammad. "Control of ITH percussive longhole drilling in hard rock." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37697.
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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.
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Bétournay, M. C. "The stability of shallow stopes of hard rock mines." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28678.
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Canadian hard rock mine extraction practices have commonly created shallow stopes, 12% of which have caved to surface, from instabilities originating from stope hangingwalls, crowns or footwalls. To date, however, mine operators have applied few of the available data gathering and design tools to strike a balance between maximum economic excavation dimension and stope viability. The preference has been to use personal mining experience.Several common rock mass environments are surveyed as well as the various ways in which shallow stopes have failed. It has been found that these rock masses develop gravity-induced movement in the form of plug failures, ravelling of rock blocks, strata failures, chimneying disintegration, and rock mass block caving.
New failure-specific analytical equations are developed here for these common failure mechanisms. They address the mechanics of the failure process and incorporate the capability to arrive at the ultimate failure outline, for comparison to the location of the bedrock surface.
This research has shown that: plug failures occur along steep, uninterrupted discontinuities bounding large blocks. Plug failure potential reduces substantially with confining compressive stress, discontinuity inclination, the absence of low friction surfaces and shearing of intact rock interrupting the discontinuity. Ravelling requires little peripheral confining stress for stabilization and prevention of block falls or slides. However, inherent conditions such as shallow dipping or vertically dipping joints can cause block falls to develop to surface. Low confining stresses, resulting from multiple stope extraction in orthogonal horizontal directions, would offer conditions suitable for plug and ravelling failures. Strata failures are caused by excessive stope spans, but the limited loading received from above strata is such, that the failure cavity created is of limited vertical extent, some 25% of the stope width. Chimneying disintegration occurs in weak rock masses with low cohesion, over narrow openings that can be as deep as 275 m. The onset of chimneying disintegration can be created by compressive stresses, but develops as a result of mobilization of the rock mass by gravity in active shear. Block caving requires large spans to develop, and stabilizing could be overcome from arching stresses overcoming bulk arching strength. Controlling instability elements are tabulated for these failure mechanisms. A limit equilibrium correlation between span and cohesion for chimneying disintegration is presented, and the controlling limits between the occurrence of chimneying disintegration and block caving is discussed. Ravelling and chimneying disintegration are the most expected failure mechanisms for shallow stopes of hard rock mines. Although failure of the shallow stope may start around its periphery, stope failure to surface would likely occur in or close to the surface crown pillar.
Although the analytical equations developed require input of in situ stresses defined by numerical modelling in order to yield a precise answer, conventional numerical modelling or empirical methods are shown to be unable to predict stope failures as the analytical equations have. A step-by-step stability analysis procedure is presented, incorporating rockmass environment, expected failure mechanism(s), and applicable data gathering and anlytical methods. (Abstract shortened by UMI.)
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Paventi, Mario. "Rock mass characteristics and damage at the Birchtree Mine." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40223.
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This thesis proposed a petrofabric classification of the rock mass domains and rock units encountered at the Birchtree Mine in the Thompson Nickel Belt (TNB), Manitoba. A program of field and laboratory studies has enabled the classification to be related to both geological and physical-mechanical properties. The classification has been aimed to advance TNB mining, mineral exploration and processing research.The thesis also considers the genesis and nature of both inherent and mining-induced rock mass damage at the Birchtree mine. An inherent rock mass damage index, D$ sb{ rm I}$, has been derived, based upon the rock unit intact strength, together with the quantity and conditions of any meso- and macro-structure present. D$ sb{ rm I}$ was closely related to rock mass domains. The physical characteristics of rock mass damage in mine developments induced both through drill-and-blast and roadheader mining were also monitored at the Birchtree Mine. This permitted the formation of a mining-induced rock mass damage index, D$ sb{ rm M}$. This was based upon decrease in the intact strength, half cast/tool marks, normalized scaling time, drift condition rating, and orientation of local structure. The type and intensity of mining-induced damage was found to be clearly related to the nature of the rock mass units and domains, as evident in their inherent damage.
Two types of mining-induced damage mechanism were evident at Birchtree. Firstly, in the inherently weak rock mass ($ rm D sb{I}10$), such as the Metasedimentary Domain, the rock units are foliated with wider spaced joints. More energy is evidently required to fragment the rock mass through what was observed to be predominantly intact rock breakage controlled by foliation. These two damage mechanisms were also clearly evident from analysis of drift and fragmentation morphology survey data. The damage mechanism associated with both forms of mining appeared to be similar, although the intensity of machine-induced damage was significantly less. Rock mass damage related to ground stress redistribution was also observed.
This thesis was motivated by the need to understand, control and minimize mining-induced damage, particularly in serpentized ultramafic domains which will host most of the future TNB mining at depth. It thus concludes by reviewing a proposed strategy for rock mass damage sensing and control in underground development and stoping, based upon the experience at Birchtree.
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Lindfors, Ulf. "Experimental study of the mechanics of rock joints." Licentiate thesis, Luleå tekniska universitet, 1996. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25833.
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Bedi, Anmol. "A proposed framework for characterising uncertainty and variability in rock mechanics and rock engineering." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/18998.
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This thesis develops a novel understanding of the fundamental issues in characterising and propagating unpredictability in rock engineering design. This unpredictability stems from the inherent complexity and heterogeneity of fractured rock masses as engineering media. It establishes the importance of: a) recognising that unpredictability results from epistemic uncertainty (i.e. resulting from a lack of knowledge) and aleatory variability (i.e. due to inherent randomness), and; b) the means by which uncertainty and variability associated with the parameters that characterise fractured rock masses are propagated through the modelling and design process. Through a critical review of the literature, this thesis shows that in geotechnical engineering – rock mechanics and rock engineering in particular – there is a lack of recognition in the existence of epistemic uncertainty and aleatory variability, and hence inappropriate design methods are often used. To overcome this, a novel taxonomy is developed and presented that facilitates characterisation of epistemic uncertainty and aleatory variability in the context of rock mechanics and rock engineering. Using this taxonomy, a new framework is developed that gives a protocol for correctly propagating uncertainty and variability through engineering calculations. The effectiveness of the taxonomy and the framework are demonstrated through their application to simple challenge problems commonly found in rock engineering. This new taxonomy and framework will provide engineers engaged in preparing rock engineering designs an objective means of characterising unpredictability in parameters commonly used to define properties of fractured rock masses. These new tools will also provide engineers with a means of clearly understanding the true nature of unpredictability inherent in rock mechanics and rock engineering, and thus direct selection of an appropriate unpredictability model to propagate unpredictability faithfully through engineering calculations. Thus, the taxonomy and framework developed in this thesis provide practical tools to improve the safety of rock engineering designs through an improved understanding of the unpredictability concepts.
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Meyers, Anthony G. "The determination of rock mass strength for engineering design /." Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phm6134.pdf.
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Fotoohi, Keyvan. "Nonlinear boundary element analysis of a rock mass with discontinuities." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41366.
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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.
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Mohammed, Marwan M. "Effects of groundwater on stability of rock and soil slopes." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28008.
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The first part of this thesis reviews in detail the state of stress due to pore water pressure, and effective stress methods in wet grounds in an attempt to present a global perspective on the subject. Through the second part of the thesis, a 2-dimensional finite element program has been developed for stress and stability analysis of wet rock and soil masses. The program uses the effective stress method which allows for a unified approach for dry and wet analysis. It computes the displacements, effective stresses and excess pore water pressure. Safety levels are then calculated in the postprocessor using rock and soil ultimate strength parameters. Three failure criteria are available. These are: Mohr-Coulomb and Hoek-Brown. The effective stress method used allows for the computation of pore water effect due to both volumetric and deviatoric changes. A case study of an open mine slope has been carried out to demonstrate the application of the developed program to practical problems.
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Wattimena, Ridho K. "Designing undercut and production level drifts of block caving mines /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17451.pdf.
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Kramadibrata, Suseno. "The influence of rock mass and intact rock properties on the design of surface mines with particular reference to the excavatability of rock." Curtin University of Technology, School of Civil Engineering, 1996. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=11287.
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The main aim of this Thesis is to examine how the rock mass and intact rock properties influence the excavatability of rock in surface mine. One of the most important decisions in the design of surface mine is the selection of mine equipment and plant. Now that increasing effort is being invested in the design and manufacture of continuous surface miners it is appropriate to examine how their performance can be related to the physical properties of the rock mass and intact rock.Over the years many attempts have been made to develop a means of assessing the excavatability of rock. Most of them are based on an empirical rating system whilst some authorities still propose the use of seismic velocity as a direct predictor of the rippability of a rock mass. On the other hand there are a number of classical models which have been developed to define the cutting force required at the pick or tooth of continuous miners.Whilst these methods have been applied with various degrees of success to the design of excavation systems there is no generally acceptable method of defining the excavatability or cuttability of a rock mass in terms of the machine power required to generate a particular rate of production.An attempt is made to overcome this deficiency by recording the intact and rock mass properties at Limestone quarry in Retznei, Austria; Openpit Gold Mines in Meekatharra and Mt Gibson of Western Australia and Openpit Coal Mine in Air Laya, Indonesia, where VASM-2D and Bucket Wheel Excavator O&K SchRs(800/1.2)15 or O&K S630 were in use in the first mine sites and Air Laya respectively to use this data to examine the relationships between the relevant dimensionless groups developed from a dimensional analysis of the problem.The dimensionless groups are obtained by examining the factors which influence the productivity of a surface miner. These include intact rock and rock ++mass properties, and machine power required for a particular rate of production and lead to the development of dimensionless groups namely, Rock Cuttability Index (RCI), Rock Mass Factor (RMF), Brittleness Index (BI), Rock Excavatability Index. The monitoring of machine power was carried out at Mt. Gibson and Air Laya mines.As a part of this study, field seismic tests were carried out at Mt. Gibson and Air Laya with the intention of seeking the most appropriate method of this type of test and analysis for excavation purposes. The test results indicate that borehole tests are the most promising and the output of seismic velocity obtained from a built-in program seismograph needs further thorough examination.The analysis of field data at all the sites proved that the most appropriate measure of discontinuities in the rock mass is the mean distance between discontinuities in a direction parallel to the cutting direction of the machine.Since the lateritic rock mass is different to other ordinary rock masses, a modified RMR is proposed. This is done by adjusting classification criteria on spacing and condition of discontinuity. The results proved that the discontinuity spacing obtained from the proposed method warrants wide application of the power cutting model developed.The RMR, Q-System and Excavatability Index are used to assess the performance of the continuous surface miners investigated. The results indicated that the Excavatability Index is the most acceptable criterion for the excavatability assessment.The outcome of this research has confirmed the significance of the RCI as a predictor of cutting performance of mechanical machines. The relationship between the RCI and REI can be used to good effect in analysing the performance of operating machines. A good example of this is given in the analysis of the performance of the BWE at the Mae Moh mine in Thailand.
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Bedair, Ayman. "Digital image analysis of rock fragmentation from blasting." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40319.
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A novel digital image analysis technique to measure the size of fragments on the surface of a muck-pile is presented in this thesis. The technique takes into consideration the physical characteristics of fragment representation and measurement problems. Using an adaptive smoothing filter prior to edge detection, each fragment on the surface is represented by a group of edge segments outlining its boundaries. These segments are then grouped to form continuous contours.A multi-layer analysis of the digital image is then formulated where fragments on the surface are grouped into three layers, each of which is categorized by global characteristics and is related to other neighbouring layers by local characteristics. These local relationships between the layers are used to approximate the missing parts of the fragment contour.
An extensive analysis of the sieving process is used in building the relationship between the shape and the size of individual fragments. Using this relation, a new multivariable measure for each fragment is developed. These measures are used in estimating the size distribution of the muck-pile and compared with other existing measurement techniques. This comparison proves the robustness of the technique developed in this thesis.
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Hadjigeorgiou, John. "A study of frictional properties of rock masses /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59612.
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The design of traditional and novel structures, e.g. underground tunnels, dam foundations, nuclear waste depositories, requires an understanding of the behaviour of rock under different stress conditions. This thesis is part of an overall research program into the behaviour of rock masses undertaken by the Department of Mining and Metallurgical Engineering at McGill University. The main objective of this project is the determination of the appropriate stress functions that describe the response of rock to applied loads. In this work, the distinction is made between intact, single discontinuity and fractured rock material.The first segment of this thesis deals with a critical evaluation of the different failure criteria for rock and rock discontinuities that have been used in the past. Their applications and limitations are identified. In the second segment of this work, the frictional behaviour of rock and rock discontinuities is defined, based on results of laboratory testing in direct-shear and triaxial compression.
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Wei, Wei. "Numerical modelling study of rock support system for deep mine haulage drift." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95194.
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Haulage drifts are used for the transportation of blasted ore from the draw point to nearby ore pass or dumping point in sublevel mining systems. During production, haulage drifts are occupied by mine operators and haulage equipment. Therefore the stability of haulage drifts is important to the safe and uninterrupted production of a mining operation. It would be advantageous to know a priori how drift stability is influenced by mining activities in the proximity of the drift. This thesis presents the results of a study to examine drift stability and rock support system performance of a haulage drift, based on a case study of Garson mine from Vale Inco, Sudbury, Canada. The Mohr-Coulomb and Hoek-Brown models are the most widely used constitutive laws to describe the elastoplastic behaviour of rock materials under load. They are available in many numerical modeling codes including Phase2 and FLAC, which were selected to perform the numerical modeling analyses in this thesis. Consequently, the Mohr-Coulomb and Hoek-Brown constitutive models are reviewed in the first place. The finite element method is selected, together with Hoek-Brown model, to study the influencing factors of stability of haulage drift; finite difference method is chosen, along with Mohr-Coulomb model, to examine the performance of rock support system design. Much information is gathered from the mine site to help understand the entire mining environment. Parameters like rock mass character, mining plan and stress environment need to be known ahead of time in preparation for building the numerical model. Consequently, a geomechanical database named Data Integrator for Mine Analysis and Design (DIMAND), including the most important features related to mining activities, has been developed. Numerical modeling results reveal that there is a dominant trend of low stress regime (postpeak) in the drift back, which results from the stoping activities in both cases of low and high horizontal to verDans les opérations de minage en vrac, le minerai est transporté des points de soutirages aux chûtes à minerai grâce aux galeries de halage. Ces galeries de halage sont utilisés par le personnel quotidiennement. Donc, la stabilité des galeries de halage est primordiale pour garantir une production constante et sécuritaire. Il serait avantageux de savoir a priori comment la galerie de halage sera affectée par l'activité minière avoisinante. Ce mémoire décrit les résultats d'une étude qui examine la stabilité et la performance du soutènement d'une galerie de halage de la mine Garson, Sudbury Ontarion, Canada, propriété de Vale. Les critères de Mohr-Coulomb et de Hoek-Brown sont les plus utilisés pour décrire le comportement du massif rocheux soumis à des contraintes. Les logiciels Phase 2 et FLAC ont été retenus pour compléter l'analyse numérique de ce travail, car les critères de Mohr-Coulomb et de Hoek-Brown y sont intégrés. Pour étudier les facteurs influençant la stabilité de la galerie de halage, un code avec éléments finis (Phase2) utilisant le critère de Hoek-Brown a été choisi. Pour évaluer la performance du soutènement, un code avec différences finis (FLAC) utilisant le critère de Morh-Coulomb a été choisi. Beaucoup de données ont été obtenues de la mine Garson afin de comprendre entièrement la zone étudiée. Des paramètres tel les caractéristiques du massif rocheux, les plans miniers, le régime de contrainte, etc. sont requis pour construire le modèle numérique. Donc, une base de données géomécanique intitulée Data Integrator for Mine Analysis and Design (Dimand)' répertoriant les caractéristiques critiques de l'activité minière a été développée. Les résultats de l'analyse numérique montrent un état de relaxation dans le toit de la galerie créé par l'extraction des chantiers dans les deux cas de faible et de fort rapport de la contrainte horizontale sur la contrainte
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Zhang, Yaohua 1963. "Nonlinear rock mass behaviour and application to stability of underground haulage drift." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99126.
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Numerical methods of analysis such as the finite element method and finite difference method have seen increasing use in recent years as tools for geomechanical mine design to predict problems of ground caving and failure. As a result of recent advances in computer technology, it is now possible to handle large-scale problems involving complex material and geometric nonlinearities at an affordable computational cost. The scope of this study is the stability of underground mine haulage drifts associated with sublevel stoping method with delayed backfill. This is one of the most popular mining methods today in Canadian underground metal mines. In this method, blasted ore is mucked with load-haul-dump vehicles and transported to the nearest dump through a nearby haulage drift. Therefore, it is crucial in a mining operation that a haulage drift remains functional during the life of the stope.This study is focused on studying the interaction between the haulage drift and nearby mining activity. The stability of the haulage drift is examined through a detailed parametric study of a finite element model representing typical mining layout most commonly adopted in Canadian underground metal mines. The model parametric study examines the influence of critical factors such as the stope mining sequences, mining depth and the distance between the stope and the haulage drift. The model is set up for nonlinear behaviour of the rock mass taking into account elastoplasticity of the rock mass and non-associated plasticity using Mohr Coulomb and Drucker Prager yield functions. Stability indicators are defined in terms of displacement, stress and the extent of yield zones. These indicators serve as a basis for assessing the effect of different parameters on the stability of the haulage drift.
From the model parametric study, it is found that stope mining causes a lateral movement of the entire drift. The severity of such movement is increased with shorter distance between the stope and haulage drift. Of all mining sequences examined, same-level mining is the most critical step. It is also found that more yield zones develop around the haulage drift as the mining depth increases and as distance between haulage drift and the stope decreases.
A 3-centre arc drift is compared with a rectangular one of the same cross sectional area. It is found that the 3-centre arc drift shape is more stable. This study also demonstrates that the nonlinear elastoplastic analysis gives more realistic results than traditional linear elastic analysis in terms of stress and displacement behaviour of the haulage drift.
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Guntumadugu, D. Raju. "Methodology for the design of dynamic rock supports in burst prone ground." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119662.
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The depth at which underground mines operate has been increasing continuously which is particularly true in the case of hard rock mining. The stability issues associated with mining at great depth pose tough challenges to engineers and researchers alike. Long-term mine developments in deep hard rock mines such as haulage drifts need to be functional during the entire life of the mine plan without posing any major stability concerns, which will otherwise hamper the production and other logistics associated with mining operations. High convergence and rockburst hazards are the main problems due to high stress and mining-induced seismicity in deep hard rock mining. In such circumstances, the understanding of drift support behavior under static and dynamic conditions is crucial for mining engineers when dealing with drift stability in deep, hard rock mines. In this thesis, current design methods for selecting drift support systems are reviewed, which are mostly dependent on empirical approaches and are geared towards static support design. Based on this, the current research focuses on ground support analysis under both static and dynamic conditions to understand drift support behavior with respect to nearby mining. Numerical modeling of drift primary and secondary supports is performed by developing two models using the 2-dimensional FLAC code. Axial loads induced in the drift support system under static and dynamic conditions are estimated for the case study hard rock mine in Canada at a depth of 1500 m. The results of numerical modeling are obtained in terms of axial loads in the drift support system, wall damage due to tension under dynamic conditions, and the extent of rock mass yielding around the drift. It is found that mining on the same level is critical to drift stability under static conditions, and rock mass yielding in the south wall of the drift (towards the ore body) extends beyond the bolting horizon once this stage begins. The results also show that by providing secondary support before same level mining commences, drift stability is greatly enhanced. The static model is calibrated through the implementation of an in-situ monitoring program of axial loads induced at the head of the rockbolt. A new load monitoring device called U-cell is successfully used for this purpose. Measured and estimated axial loads are then compared and found to be in good agreement. The preliminary dynamic analysis shows that a peak particle velocity of 2.0 m/s at the periphery of the drift will cause wall damage more than 1.0 m when only primary supports are provided, and around 0.5 m when secondary supports are installed along with the primary ones, and when there is no nearby mining taking place. The effects of lower level and same level mining under dynamic conditions are also examined, and wall damage and rock mass yielding are estimated. The estimation of wall damage depth is crucial in designing dynamic rock supports. It is demonstrated that wall damage due to various levels of ground motion can be estimated by dynamic numerical modeling. Finally, a methodology for the design of dynamic rock supports is presented, which is based on the selection of yielding support type and pattern, the estimation of the ejection velocity, and the volume of wall damage as obtained from dynamic modeling.La profondeur des mines souterraines a augmenté de manière continue, particulièrement en ce qui concerne les mines en roches dures. Les problèmes de stabilité associés aux mines profondes représentent comme des defis pour les exploitants, comme pour les chercheurs. Les développements miniers à longue durée de vie dans les mines profondes, tels que les galléries de roulage, doivent rester fonctionnels pour toute la durée de l'exploitation, sans poser de soucis majeurs, qui, sinon, nuiraient à la productivité et à l'organisation des opérations minières. Les fortes convergences et le risque de coup de terrain constituent les principaux problèmes dus aux fortes concentrations de contraintes et à la sismicité minière induite dans les mines profondes en roches dures. Dans de telles circonstances, la compréhension du comportement du soutènement des galeries sous l'effet de chargements statiques et dynamiques est essentielle pour les ingénieurs miniers confrontés aux questions de stabilité dans les mines profondes en roches dures. Dans cette thèse, nous exposons les méthodes courantes de dimensionnement du soutènement des galeries, qui reposent principalement sur des approches empiriques et ont pour objectif d'assurer la stabilité sous chargement statique. Sur cette base, la recherche se concentre sur des méthodes de dimensionnement du soutènement sous des charges statiques et dynamiques, dans le but de comprendre le comportement du soutènement des galeries adjacentes aux zones en cours d'exploitation. La modélisation numérique du soutènement primaire et secondaire des galeries est réalisée en développant deux méthodes recourant au code bidimensionnel FLAC. Les charges axiales dans le soutènement des galeries sont estimées sous des sollicitations statiques et dynamiques, dans le cas d'une mine canadienne en roche dure, à 1500 m de profondeur. Les résultats de la modélisation numérique sont présentés en termes de charge axiale dans le soutènement, d'endommagement des parois sous l'effet des tractions induites par les sollicitations dynamiques et de l'extension de la zone rompue autour des galeries. Nous montrons ainsi que l'exploitation sur le même niveau a des conséquences importantes sur la stabilité des galeries en chargement statique, et qu'au niveau du parement sud (i.e. du côté du gisement), la zone rompue s'étend au-delà de la longueur des boulons au début de cette étape. Les résultats montrent aussi que la stabilité de la galerie de roulage est très nettement améliorée si un soutènement secondaire est mis en œuvre lorsque commence l'exploitation sur le même niveau. Le modèle statique est calibré en utilisant des mesures in situ de la charge axiale sur les têtes de boulons. Pour ce faire, un nouveau dispositif de mesure de la charge, appelé « U-cell » a été utilisé avec succès. Les mesures de charge et les résultats de la modélisation sont comparés et sont en bon accord. L'étude dynamique préliminaire montre que des vitesses de points matériels de l'ordre de 2.0 m/s à la périphérie de la galerie de roulage induisent un endommagement au delà de 1.0 m de profondeur lorsque seul le soutènement primaire est mis en œuvre, et au delà de 0.5 m lorsqu'un soutènement secondaire est installé, pour peu qu'il n'y ait pas de zone en exploitation à proximité. Les effets de l'exploitation sur le même niveau et sur un niveau inférieur sont également comparés; l'endommagement des parois et la rupture de massifs rocheux sont estimés. L'estimation de l'endommagement de la paroi est essentielle afin de dimensionner le soutènement dynamique. On montre que l'endommagement de la paroi peut être estimé par modélisation numérique, pour différents niveaux de vitesses du terrain. Pour finir, une méthodologie pour le dimensionnement du soutènement dynamique est présentée; elle est basée sur la sélection du type et de la géométrie du soutènement. La vitesse d'éjection et l'endommagement de la paroi sont estimés par modélisation numérique.
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Priscu, Doina Maria. "Double-porosity modelling of groundwater flow through fractured rock masses." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37280.pdf.
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Forrest, Peter. "Layout design for interactive zones in longwall multiple seam mining." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43854.
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Appalachia requires design guidelines for the increasingly popular multi-seam longwall method. Entry layouts often depart from the ideal when finally developed. The thesis examines the occurrence of ground control problems, and possibilities for improvements in strata control, in a variety of undermining situations. The effects of upper seam loading on undermining operations are invest~gated using physical modelling. Photoelastic stress analysis is used as a powerful research tool to analyze complex multiple seam entry systems. Yield pillar use is also examined, in anticipation of their widespread application for ground control. Case examples support the research findings, and specific conclusions aim to assist layout design in interactive zones.
Master of Science
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Cheung, William K. W. (Kwok Wai). "Inferring surface structure of rock piles from range images." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56767.
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This thesis deals with the problem of applying computer vision techniques in an underground mine environment. In particular, the problem of the localization and identification of oversized rock fragments prior to secondary breakage, following the initial drilling and blasting operation is addressed. The strategy employed is based on the methodologies developed for reconstruction and interpretation of range image data. Discrete rock pile images acquired using the NRCC/McGill laser rangefinder were used in this study. The main contribution of this thesis is the complete study of the paradigm which involves: range data acquisition, surface reconstruction, segmentation, and fitting of parametric shape models. The final representation obtained from the model, describing the spatial and geometric properties of each rock fragment and can be used to control an automated rock-breaking mechanism. To support the strategy developed, a number of experimental results at different processing stages are presented.
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Hardy, Andrew John 1965. "Fragment size distribution of in situ rock masses from drill core." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/278324.
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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.
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Gumusoglu, M. Cetin. "Analysis of underground excavations in strain softening rock masses." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38339.
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Reeves, Bryan Anthony. "Slope stability radar /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17049.pdf.
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