Research Projects

Fracture Network Reconstruction in Sedimentary Rock Geothermal Reservoir by Supercritical CO2 – WANG Shen (Ph.D., 2017 – Date)

Coal measure sedimentary rock thermal reservoirs, due to their relative shallow depth and high density of natural fractures, have potential and great economic value for heat energy exploitation in deep coal mines. In this project, the physical mechanisms of fracturing natural cracks and structural planes by injection of supercritical CO2 flow under the coupling interaction between thermodynamics, seepage and stress are analyzed by using X-ray 3D microscope and triaxial supercritical CO2 fracturing laboratory testing system. The crack initiation and propagation constitutive law under the coupling interaction are put forward based on fracture mechanics, percolation mechanics and thermodynamics. The characterization of the fracture network is based on topology, differential manifold, and fractal theory. The variation of fracture network structure in coal measure sedimentary rock thermal reservoirs is studied using numerical finite-discrete coupling simulation method. The prediction and evaluation of restructuring effectiveness for coal measure sedimentary rock thermal reservoirs by supercritical CO2 flow fracturing are built up to establish the basic theory for the application of CO2 fracturing technique in coal measure sedimentary rock thermal reservoirs.

Study on the elastic wave response characteristics in the loaded gas-filled coal – WANG Yungang (Visiting scholar, 2016 – 2017)

Based on the seismic rock physics and the applied acoustic theory, the project aims to investigate the elastic wave propagation rules in the tectonic coal or soft rock with stress-strain method (low frequency) and ultrasonic wave testing technology (high frequency). Firstly the kinematics and dynamics characteristics of the elastic wave in the coal or rock, gas-filled coal, and the loaded gas-filled coal or rock, are studied, accordingly the elastic wave propagation dynamic mechanism is revealed. Then the elastic wave propagation rules and attenuation characteristics in different loading stages during the gas seepage process of gas-filled coal under the triaxial compression are studied, correspondingly the elastic wave dynamic mechanism under the triaxial compression is studied, especially during the creep process.

Research on the intelligent top coal caving system in top coal caving mining – LIU Chuang (Ph.D., 2016 – 2017)

Study on the relationship among the ground pressure, top coal caving, and top coal movement in longwall top coal caving panel. Determine the synergy relationship among the shearer mining, shield advancing, rear conveyor transporting and top coal caving. Study on the relationship among the top coal caving, shield resistance, the stability of the coal wall and the ground control in the stope. Establish a comprehensive optimization technology of longwall top coal caving process model. Study and put forward an algorithm to control the coordination of top coal caving. The ultimate goal is to achieve a set of intelligent top coal caving system software.

Study on the mechanism of mine geological disaster and the technology of hedge – GAO Na (Visiting scholar, 2017 – 2018)

Based on the existing results and the numerical simulation technology, to carry out micro research on the characterization of rock rheological and environmental factors, the mechanism of the disaster caused by rheological factors, simulation of the rheological process in mined out areas and the relative technology of hedge.

Expansive cement and hole notching used to enhance rock fragmentation during destress blasting – Flavie Arseneau (M.Eng., 2016 – Date)

Destress blasting is a common rock blasting technique used to alleviate stresses in deep underground mines. Destress blasting has for main purpose to change the rock mechanical properties by fragmentation of the rock mass. The goal of the project is to test rock samples under uniaxial compressive strength, in order to simulate destress blasting. The rock sample will be evaluated at 3 different depth, and will be tested with expansive cement and hole notching. The output of the project will be a step forward into optimizing the destress blasting process.

Improved Recovery in Burst Prone Ground Using Destress Blasting – Isaac Vennes (Ph.D., 2014 - Date)

Destress blasting is the application of explosive energy to rock to reduce its stiffness and stored strain energy, and is generally used during drifting to reduce the burst proneness of the mining face. The technique can also be used to reduce stress in ore pillars formed when bulk mining a steep orebody, where the pillar hanging wall is destressed such that the ore pillar is in stress shadow of destress panel. This study aims to quantify the effect of this destress blasting strategy with a numerical modelling back analysis of an ongoing panel destress blasting program at a deep, Canadian hard rock mine. The numerical model is calibrated based on stress changes measured with stress cells on site. The effectiveness of the blast based on the changes in stored strain energy, Burst Potential Index, and Brittle Shear Ratio.

Evaluation of Fault-slip Potential in Underground Mines – Atsushi Sainoki (Post-Ph.D., 2014 – 2016)

Based on the knowledge gained from the preceding project “Dynamic Modelling of Mining-induced Fault-slip”, a case study is conducted for a deep hard rock mine in Canada. The primary objective of this project is to determine the most appropriate simulation technique for the dynamic modelling of fault-slip in underground mines; numerical modelling methods and friction laws are focused on whilst considering the methodologies developed in the previous project. After the selection, it is attempted to establish a simple, useful engineering guideline that helps mining engineers estimate the intensity of ground motion caused by seismic waves arising from fault-slip. This research project significantly contributes to the enhancement of mine safety as well as stable production.

Dynamic Modelling of Mining-induced Fault-slip – Atsushi Sainoki (PhD, 2014)

Fault-slip caused by mining activities in a deep underground mine can cause devastating damage to openings. Although a number of studies have been undertaken with numerical simulation techniques in order to estimate the magnitude of fault-slip taking place in underground mines, only the static behaviour of faults has been focused on with the classical Mohr-Coulomb failure criterion. As fault-slip is a dynamic phenomenon producing intense seismic waves, it is of pivotal importance to deepen knowledge about the underlying mechanism of fault-slip and its dynamic behaviour. This study focuses on the development of novel simulation techniques that can adequately capture the dynamic behaviour of a fault during fault-slip, i.e., slip rate and seismic waves. Through this project, new methodologies to simulate fault-slip caused by the breakage of asperity shear were developed, whereby peak particle velocity caused by seismic waves arising from fault-slip can be estimated. The information is essential in optimizing dynamic support design for underground openings.

Roadway Stability of Underground Coal Mines – Lishuai Jiang (PhD, 2013)

The stability of roadways is a long-standing issue in underground coal mines, especially for roadways that serve and ensure the safe production of longwall panels. Ground stability and failure mechanisms of roadways vary depending on stress, geological and geotechnical conditions. However, the difficulty of maintaining roadway stability stems from the weak surrounding rock mass and continuous geotechnical disturbance. Serving the longwall panels, roadways are always located in the coal seam, which generally has relatively weak properties compared to rood and floor rock formations. Secondly, after coal in a longwall panel is extracted, and a void (goaf) behind the face is created, rock fracturing and yielding as well as stress concentration in the surrounding rock take place. Because of coal extraction, the gateroad is subjected to a complex loading pattern. This project aims to study effective ground controlling strategy for roadway in underground coal mines, including new rockmass model development, roadway layout and support design optimization.

Stability of Rock Slopes Subjected to Heavy Rainfall – Hassan Basahel (PhD, 2013)

Rock slope stability requires a good knowledge of the physical and mechanical conditions of rock mass such as the status of weathering, decomposition, the strength parameters especially for discontinuities surfaces and the geometries parameters for the rock slope (angles and direction of the slope face and joints). Furthermore, another aspect should be considered when analyzing rock slope stability is the triggering factor. This triggering factor could be water (surface water or pore pressure) or/and seismic waves. In this research, the stability assessment for rock slopes have been conducted under the normal conditions of the rock slope, as well as the influence of the pore water pressure on the slope instability. Some areas in south-west of Saudi Arabia have been taken as case studies, since these areas are subjected to heavy rainfall and rock instability especially in rainstorms seasons. The main purpose of the study is to establish a Hazard index that takes into account the effect of the probability of failure with the intensity. The analysis will be conducted using the statistical analysis and the numerical modelling with considering the effect of water pressure on the stability conditions. Moreover, the effect of road cuts curvatures will also be taken into account in the stability analysis process.

A Constitutive Model for Narrow Vein Mines containing Weak Ground Material – Andrew Pyon (M.Eng., 2013)

Operating in weak narrow vein mines presents many issues in terms of ore productivity. Maintaining stable mining excavations and limiting unplanned overbreak are some of the main problems in narrow vein mining. The use of numerical modeling became a popular method for this since it is capable of examining stress patterns and identifying rockmass failure. This paper will focus on creating a 3-dimensional constitutive numerical model for narrow vein mines that incorporate weak rockmass properties. The selected case study will be Lapa Mine, an underground narrow vein mine joining a weak material known as talc-chlorite-schist. The construction of this model will be associated with the unplanned ore dilution determined by surveyed profiles from the mine site.

Geotechnical risk assessment of haulage drifts during the life of a mine plan – Wael Elrawy Abdellah (PhD, 2014),G,Raju (PhD, 2013),Shahe Shnorhokian (Research Associate) - NSERC-Vale Inco CRD Project

The objective of this project is to develop new, semi empirical planning tools capable of predicting where and when a mine haulage drift is due for enhanced support installation. Such tools are  developed as functions of drift stability condition with respect to anticipated stope extraction sequence and mine scheduling in tabular ore deposits extracted with sublevel stoping (longhole mining) methods. First, a comprehensive database is built for the orezone or mining block selected for the project case study following a number of site visits for site characterization and collection of necessary information and data. The second stage aims to establish a geotechnical risk assessment scheme. This is done by delineating all possible haulage drift stability (or instability) conditions associated with the mining system and linking each of them to a corresponding geotechnical risk factor or index. The next stage involves the development of numerical models to help examine influences of individual factors including stope size, stope type, orebody dip and orientation with respect to principal stresses, rock mass quality, mining depth, drift shape and size and the distance between the drift and the orebody. Three-dimensional models of the case study mining block are constructed to examine drift stresses associated with individual stope recovery as the mining block is extracted. Model results include stress distribution around the drift, extent of yield zones as well as drift deformation profiles. In stage 4, numerical modelling results are validated with well documented field observations and monitoring results obtained from the mine area under study.

Strength Characterization of Cemented Rockfill – Isaac Vennes (M. Eng, 2014)

In this research, backfill testing for uniaxial compressive strength (UCS) is carried out. Laboratory tests are planned to help shed light on the mechanical strength of cemented rockfill as practiced at the Birchtree Mine of Vale in Thompson, Manitoba. Further testing with low and high binder content as well as controlled particle size distribution are planned to help evaluate the effect of these parameters on the UCS results. More samples with different binder percentages and fines content ratios will be tested for UCS to help understand the influence of these parameters on the strength of CRF. In order to ensure representative results, large cylindrical samples will be prepared and tested. A number of benefits will be drawn from these laboratory tests. Knowing the UCS of the CRF currently in use will help in the calculation of the apparent safety factor according to static design equations based on limit equilibrium methods. While an increase in the binder content is known to increase the backfill strength, it is important to assess the need for such an increase to justify the added cost of binder.  The benefit of particle size gradation control over the use of “as is” development waste will be realized after the test results are analyzed. The UCS values will also serve as input parameters for the numerical models to be developed.

Comparative Stability Analysis of Tailings Storage Facilities - Jenyfer Mosquera Palacios (M.Eng, 2013)

Tailings Storage Facilities (TSFs) are vast structures that respond to site-specific characteristics, rate of production, placement techniques, rate of raise, and the physical and mechanical properties of tailings. As a common denominator, all TSFs are in some degree vulnerable to failure due to liquefaction, poor operations management, slope instability and/or unusual climatic events. In practice, slope stability is determined by calculating a minimum Factor of Safety (FOS) using one or various Limit Equilibrium Methods (LEMs). However, it has been proven that relying exclusively on the limit equilibrium approach is not accurate because it is basically a static method that does not take into account the stress-strain distribution and displacement experienced by the constitutive materials of a TSF at its different stages of construction. In order to overcome these limitations of the LEMs, the finite element - Shear Reduction Technique (SRT) has been currently used as a more reliable tool for TSFs stability assessment. This project deals with a comparative stability analysis of two typical TSFs, namely, an upstream tailings storage facility (UTSF), and a water retention tailings dam (WRTD) under static and pseudo-static states using simplified and rigorous LEMs and the SRT. Additionally, and taking into consideration the intrinsic uncertainty of tailings properties, sensitivity and probabilistic analyses in the form of Monte Carlo Simulation (MCS) and the Point Estimate Method (PEM) are applied to determine the Probability of Failure (Pf) and Reliability Index (β) of the TSFs at the end of construction.

Geotechnical Performance of Tailing Dams: A Stochastic Design Approach – Tarek Hamade (PhD, 2013)

Mine tailings dams are geotechnical structures that are designed to provide adequate and safe storage of tailings materials both during and after the end of mine life. The design of such structures is thus of utmost importance not only to the success of the mining operation, but more importantly to the safety of the surrounding environment such as freshwater resources, wildlife, and community developments. The design of tailings dams is currently based on limit equilibrium methods (LEM), which are used to calculate slope stability safety factors under various operational loads. The minimum safety factor obtained from these analyses is retained to be the design safety factor. A number of slope stability LEM’s have been developed and well documented for the geotechnical design of mine tailings dams; and these are currently being used in geotechnical design.  However, LEM’s suffer from a number of shortcomings, most notably the lack of information on dam deformation and the interaction between effective stress and pore pressure. For this, advanced numerical modeling techniques accounting for the hydro-mechanical coupling occurring in the dam structure have been developed. These models provide much greater insight into the geotechnical behavior of the tailings dam. However, both LEM and numerical modeling approaches are deterministic in nature, i.e., they are based on using the mean value of the material properties as model input parameters; thus, they do not take into consideration the inherent uncertainty of the construction material properties – a fact that is well known to the geotechnical engineer and yet, needs to be addressed.

In this thesis, stochastic analysis approaches such as the Monte Carlo method are adopted to investigate the effect of the inherent uncertainty in material properties on the design factor of safety. Both LEM and coupled hydro-mechanical numerical models are first developed and the results for deterministic models are compiled. These are then compared with the result obtained from stochastic analyses. A case study of a new water retention tailings dam project design with well documented geotechnical data is adopted throughout the thesis study.

Hydromechanical behaviour of hydro-electric power pressure tunnels -André Rancourt (PhD,2010)

The increase in demand for electrical energy has pushed the industry to execute hydro-electric power projects in sites with less favourable geological conditions all over the world. The design of unlined pressure tunnels for hydro-electric power projects has become an increasingly complex task requiring that highly heterogeneous, anisotropic and non-linear rock mass be well characterized and understood. While unlined pressure tunnels are the most economical, compared to lined and semi-lined tunnels, they are prone to hydraulic jacking. This project places emphasis on the preliminary phase when no field measurements are available yet. The spatial distribution of the minimum stress required to control hydraulic jacking around unlined pressure tunnel is computed, and the topographic effects, the rock cover-to-tunnel diameter ratio, the presence of geological feature are accounted for in the design model. Tunnel induced stresses are compared to those obtained by the Norwegian design criterion, and a correction factor called Cover Alteration Ratio (CAR) is derived for each site. Cases where the Norwegian criterion is not adequate are identified and it is proposed to deal with these situations by adopting a larger factor of safety.

Hydromechanical behaviour of hydro-electric power pressure tunnels – André Rancourt (PhD,2010)

The design of pressure tunnels in hydro-electric power projects suffer from lack of field investigation and difficulties to characterize and to model the highly heterogeneous, anisotropic and non-linear nature of the rock mass. Several recent contributions in the broad field of hydromechanics provide interesting approaches that will improve investigation and allow for more realistic theoretical and modelling aspects. Especially, coupled process involving mechanical- hydraulic interactions are gaining interest and practitioners are beginning to acknowledge their fundamental effects on global system interactions. This study aim to review available developments that could provide useful tools for the engineer involved in the safe and reliable pressure tunnel design.

Quantification of unplanned ore dilution associated with longitudinal sublevel stoping – development of new numerical-empirical models - Hind Zniber El Mouhabbis (M. Eng, 2013), Rory Hughes (M. Eng. 2011)

Unplanned ore dilution has a direct influence on the profitability of a mining operation. This project focuses on better understanding of the factors contributing to unplanned ore dilution in longhole stoping environment, and how it can be estimated using stope recovery information and geomechanical mine design parameters, together with numerical modelling tools.

Study on Meso-mechanism of Coal-rock Damage & Electromagnetic Emission Response and Its Application - Chen Wenxue (PhD 2009)

In order to predict dynamic mine disasters, especially coal and gas outburst in coal mines, technology such as Computerized Tomography Method is used. This helps to study the complex characteristics of coal-rock using digital image processing to get the information of deformation and fracturing in coal-rock. Using the meso-mechanics damage and material mechanics theories, the damage evolution equations and constitutive equations of coal rock in meso-scale are built by experimental work. Using a series of experiments, this project aims to discover a relationship between dynamic disasters and electromagnetic emission, by analyzing the response relation between EME and actual coal-rock damage process, which could then be used to create sensitivity indexes in predicting coal-rock outbursts. This project aims to develop a convenient scientific method & system to monitor dynamic disasters in mines.

Explosive free rock breakage using expansive cements - Anand Ram Musunuri (M. Eng. 2009)

Expansive cements are used extensively in the demolition industry and also for dimension stone quarrying. Different types of commercially available expansive agents were compared and tests are to be performed on different rock types to understand the expansive characteristics under loaded conditions.

Evaluation of Long-Hole Mine Design Influences on Unplanned Ore Dilution – John G Henning (PhD, 2007)

Design and Practice of Cemented Rockfill - Muhammad Zaka Emad (PhD Candidate),Shahe Shnorhokian (Research Associate)-Vale Project

Ore dilution due to backfill failure into adjacent stope being mined is very common in underground metal mines. Since the beginning of twentieth century cemented rock fill (CRF) has been in practice, and a lot of research was done on for the development of low cost CRF mix design. Many researchers have made efforts to explain CRF failure; some empirical designs for static loading have also been presented but so far they are unable to delineate CRF failure mechanisms. Numerical modelling was also attempted by a number of researchers, but such attempts did not fully explain ore dilution due to CRF failure. It has been proposed by many researchers that blast induced vibrations account for backfill failure. Up until now, little work has been done on the effect of blasting on backfill failure. This research project is being proposed to address the issue of ore dilution due to backfill failure that is initiated by blast induced vibrations among other factors, while considering stope design and setting, planned mining sequence, strength of the backfill material as well as the geotechnical properties of the host rock mass. This project is for implementation at the Birchtree mine of Vale.

Evaluation of Long-Hole Mine Design Influences on Unplanned Ore Dilution – John G Henning (PhD, 2007)

Unplanned ore dilution or stope overbreak, which has a direct and large influence on the cost of a stope, and ultimately on the profitability of a mining operation, can be attributed to both the mining process and to geologic setting. The research program, applicable to a wide range of underground mines employing the blasthole mining method to extract tabular orezones, focuses on examining factors attributable to the generation of unstable stope hanging-walls. The primary objective of the project is to establish new semi-empirical models for stope and orezone design, with respect to anticipated stope overbreak. Identified factors influencing unplanned dilution, such as induced stress environment, stope geometry, and the setting of individual stopes within the orezone extraction sequence are to be considered. The research undertaken incorporates a variety of components, including (1) parametric 3D modelling to examine influences of individual factors on hanging-wall overbreak, (2) case example analysis, (3) ore zone extraction sequence modelling, using 3D elastic modelling. Design criteria, developed from the parametric modelling, will be applied to the orezone sequence modelling to develop semi-empirical trends for stope dilution, as functions of stope design and construction.

Coupled Analysis of Staged Construction of Upstream Tailings Dams – Bassam Saad (PhD, 2008)

The objective of this project is to improve the understanding of the interactions between upstream tailings dam (UTD) zones during their staged construction. It is hoped to develop reliable tools to help evaluate the risks of limit equilibrium analyses, which are commonly used in industry to judge the safety of UTDs during their staged construction. For this purpose thorough liquefaction analyses under different tailings materials and foundation characteristics are performed implementing the appropriate constitutive models. Conclusions concerning instability are evaluated against those obtained from limit equilibrium approach. It is also planned to investigate some field problems that are commonly encountered during the operation-construction of UTDs including raise of the p