Publications

@article{Mohantyetal.2017,

title = {Effect of Blasting Vibrations from Deck Blasts on Pit Wall Stability},

author = {Bibhu Mohanty and Ali Siamaki and Kamran Esmaieli},

url = {https://omre-researchgroup.com/mse-jfb2017/

https://www.isee.org/publications/blasting-and-fragmentation-journal},

isbn = {1937-6359},

year  = {2017},

date = {2017-09-09},

urldate = {2017-09-09},

journal = {Blasting and Fragmentation Journal},

volume = {11},

number = {1},

pages = {37-47},

abstract = {Large scale open pit mining and quarrying operations dictate safe and reliable pit wall stability. The current approach of employing the particle velocity-scaled charge distance approach to estimate and minimize blast-induced damage to residential structures is considered inadequate to protect rock slopes. This study utilizes close-in blasting vibration data as input to an advanced 2D numerical code to study its applicability to serve as a predictive tool in terms of blast-induced rock slope failure. Two tri-axial accelerometer stations, consisting of high-frequency and high-amplitude (20 kHz, 100g) sensors, located within ~100m of the blast, but at two different bench levels, were used to monitor production blasts in a quarry. The production blast consisted of double-decked explosive loads in 125 mm (5 in) diameter holes, with an inter-deck delay of 42 ms, and each deck consisting of 130 kg (285 lb) of emulsion explosive. The blasting vibration data obtained at the two bench levels were critically analyzed, and the vibration results served as input to the numerical model consisting of a single rock block with a 45-degree persistent joint plane but with specified strength properties, significantly different from that of the intact rock. The model was able to characterise progressive accumulation of damage in the form of micro-cracks along the joint surface as a function of the relatively low vibration load from successive explosive decks. The results showed that such a numerical model can serve as a very good diagnostic and predictive tool, when backed up by careful vibration monitoring and further supported by detailed slope monitoring. },

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Eivazy-2017,

title = {Modelling Geomechanical Heterogeneity of Rock Masses Using Direct and Indirect Geostatistical Conditional Simulation Methods},

author = {Hesameddin Eivazy and Kamran Esmaieli and Raynald Jean},

doi = {https://doi.org/10.1007/s00603-017-1293-0},

year  = {2017},

date = {2017-08-10},

urldate = {2017-08-10},

journal = {Rock Mechanics Rock Engineering},

volume = {50},

number = {12},

pages = {3175-3195},

abstract = {An accurate characterization and modelling of rock mass geomechanical heterogeneity can lead to more efficient mine planning and design. Using deterministic approaches and random field methods for modelling rock mass heterogeneity is known to be limited in simulating the spatial variation and spatial pattern of the geomechanical properties. Although the applications of geostatistical techniques have demonstrated improvements in modelling the heterogeneity of geomechanical properties, geostatistical estimation methods such as Kriging result in estimates of geomechanical variables that are not fully representative of field observations. This paper reports on the development of 3D models for spatial variability of rock mass geomechanical properties using geostatistical conditional simulation method based on sequential Gaussian simulation. A methodology to simulate the heterogeneity of rock mass quality based on the rock mass rating is proposed and applied to a large open-pit mine in Canada. Using geomechanical core logging data collected from the mine site, a direct and an indirect approach were used to model the spatial variability of rock mass quality. The results of the two modelling approaches were validated against collected field data. The study aims to quantify the risks of pit slope failure and provides a measure of uncertainties in spatial variability of rock mass properties in different areas of the pit.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{bamford-ijmre17,

title = {A real-time analysis of post-blast rock fragmentation using UAV technology},

author = {Thomas Bamford and Kamran Esmaieli and Angela Schoellig},

doi = {10.1080/17480930.2017.1339170},

year  = {2017},

date = {2017-06-19},

urldate = {2017-06-19},

journal = {International Journal of Mining, Reclamation and Environment},

volume = {31},

number = {6},

pages = {439-456},

abstract = {The current practice of collecting rock fragmentation data for image analysis is highly manual and provides data with low temporal and spatial resolution. Using Unmanned Aerial Vehicles (UAVs) for collecting images of rock fragments improves the quality of the image data and automates the data collection process. This work presents the results of laboratory-scale rock fragment measurements using a UAV. The goal is to highlight the benefits of aerial fragmentation analysis in terms of both prediction accuracy and time effort. The pile was manually photographed and the results of the manual method were compared to the UAV method.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Urli-Esmaeieli2016,

title = {A stability-economic model for an open stope to prevent dilution using the ore-skin design},

author = {Virginie Urli and Kamran Esmaieli},

doi = {10.1016/j.ijrmms.2015.12.001},

year  = {2016},

date = {2016-01-04},

journal = {International Journal of Rock Mechanics and Mining Sciences},

volume = {82},

pages = {71-82},

abstract = {In this study, the ore-skin design approach is presented in the context of a hypothetical open stope mine. A stability-economic model was developed to estimate the ore-skin thickness that can be left unmined to maintain the integrity of an open stope and control excessive ore dilition from hangingwall sloughage. The first stage of the approach consists of performing a cost-profit analysis to determine an economic break-even ore-skin thickness. The second stage includes using discrete element numerical methods to evaluate the stability of a certain ore-skin thickness. Two numerical methods were employed for this assessment, including a discrete fracture network (DFN) method and a hybrid discrete element / discrete fracture network model. Results indicated that the minimum ore-skin thickness required depends on the quality of governed rock mass and can be a function of stope lifetime.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{esmaieli-mt15,

title = {Application of DFN–DEM modelling in addressing ground control issues at an underground mine},

author = {Kamran Esmaieli and John Hadjigeorgiou},

doi = {10.1179/1743286315Y.0000000013},

year  = {2015},

date = {2015-07-11},

journal = {Mining Technology},

volume = {124},

number = {3},

pages = {138-149},

abstract = {A field case study is presented of an underground Canadian mine reporting ore pass problems. The ore pass has significantly degraded where a fault zone was intercepted. A geotechnical site investigation identified four rock mass domains along the ore pass including a fault zone. This information was used to generate a discrete fracture network (DFN) model for the rock mass. A kinematic analysis revealed that structurally controlled failure was not the only failure mechanism for the ore pass. The DFN model was subsequently used to develop 2D synthetic rock masses of the four rock mass domains. This allowed investigation of the influence of impact-induced damage from the transiting material. The maximum impact-induced damage was recorded for the fault zone. The mine adopted the recommendation to install a grizzly at the ore pass collar and cable bolts around the degraded ore pass zone. The recommendations contributed to the structural integrity of the ore pass.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{emaieli-ijnamg15,

title = {Capturing the complete stress–strain behaviour of jointed rock using a numerical approach},

author = {Kamran Esmaieli and John Hadjigeorgiou and Martin Grenon},

doi = {10.1002/nag.2346},

year  = {2015},

date = {2015-01-10},

journal = {International Journal for Numerical and Analytical Methods in Geomechanics},

volume = {39},

number = {10},

pages = {1027-1044},

abstract = {This paper presents the results of a series of numerical experiments using the synthetic rock mass (SRM) approach to quantify the behaviour of jointed rock masses. Field data from a massive sulphide rock mass, at the Brunswick mine, were used to develop a discrete fracture network (DFN). The constructed DFN model was subsequently subjected to random sampling whereby 40 cubic samples, of height to width ratio of two, and of varying widths (0.05 to 10 m) were isolated. The discrete fracture samples were linked to 3D bonded particle models to generate representative SRM models for each sample size. This approach simulated the jointed rock mass as an assembly of fractures embedded into the rock matrix.



The SRM samples were submitted to uniaxial loading, and the complete stress–strain behaviour of each specimen was recorded. This approach provided a way to determine the complex constitutive behaviour of large-scale rock mass samples. This is often difficult or not possible to achieve in the laboratory.



The numerical experiments suggested that higher post-peak modulus values were obtained for smaller samples and lower values for larger sample sizes. Furthermore, the observed deviation of the recorded post-peak modulus values decreased with sample size. The ratio of residual strength of rock mass samples per uniaxial compressive strength intact increases moderately with sample size. Consequently, for the investigated massive sulphide rock mass, the pre-peak and post-peak representative elemental volume size was found to be the same (7 × 7 × 14 m).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{esmaieli-cim14,

title = {Impact-induced damage on foliated ore pass walls},

author = {Kamran Esmaieli and John Hadjigeorgiou},

url = {http://www.cim.org/en/Publications-and-Technical-Resources/Publications/Journals/2014/01/JOUR-2014-01-01/JOUR-2014-01-07},

year  = {2014},

date = {2014-01-01},

journal = {CIM Journal},

volume = {5},

number = {1},

abstract = {We conducted a series of numerical experiments to investigate the influence of rock mass foliation on impact-induced damage on ore pass walls. The 2D Particle Flow Code was used to simulate three distinct rock masses surrounding an ore pass, characterized by foliation angles of 60°, 90°, and 120° (clockwise from horizontal). Subsequently, we projected a rock fragment against the ore pass walls at a constant impact angle and velocity. The resulting damage increased when the angle of intersection between the ore pass wall and the rock mass foliation decreased.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{esmaieli-rmre13,

title = {Stability Analysis of the 19A Ore Pass at Brunswick Mine Using a Two-Stage Numerical Modeling Approach},

author = {Kamran Esmaieli and John Hadjigeorgiou and Martin Grenon},

doi = {10.1007/s00603-013-0371-1},

year  = {2013},

date = {2013-01-24},

journal = {Rock Mechanics and Rock Engineering},

volume = {46},

number = {6},

pages = {1323-1338},

abstract = {The longevity of ore pass systems is an important consideration in underground mines. This is controlled to a degree by the structural stability of an ore pass which can be compromised by changes in the stress regime and the degree of fracturing of the rock mass. A failure mechanism specific to ore pass systems is damage on the ore pass wall by impact load or wear by material flow. Structural, stress and material flow-induced failure mechanisms interact with severe repercussions, although in most cases one mechanism is more dominant. This paper aims to provide a better understanding of the interaction of ore pass failure mechanisms in an operating mine. This can provide an aid in the design of ore pass systems. A two-stage numerical approach was used for the back analysis of an ore pass at Brunswick mine in Canada. The first stage in the analysis relied on a 3D boundary element analysis to define the stress regime in the vicinity of the ore pass. The second stage used a synthetic rock mass (SRM) model, constructed from a discrete fracture network, generated from quantitative rock mass field data. The fracture network geometry was introduced into a bonded particle model, in a particle flow code (PFC). Subsequently, the ore pass was excavated within the SRM model. A stability analysis quantified the extent of rock mass failure around the ore pass due to the interaction of pre-existing fractures and the failure of the intact rock bridges between these fractures. The resulting asymmetric failure patterns along the length of the ore pass were controlled to a large degree by the in situ fractures. The influence of particle flow impact was integrated into the model by projecting a discrete rock fragment against the ore pass walls represented by the SRM model. The numerical results illustrated that material impact on ore pass walls resulted in localised damage and accelerated the stress-induced failure.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{esmaieli-rmre10,

title = {Selecting Ore Pass-Finger Raise Configurations in Underground Mines},

author = {Kamran Esmaieli and John Hadjigeorgiou},

doi = {10.1007/s00603-010-0128-z},

year  = {2010},

date = {2010-12-28},

journal = {Rock Mechanics and Rock Engineering},

volume = {44},

number = {3},

pages = {291-303},

abstract = {Material transfer in underground mines often relies on ore and waste pass systems. In mines where ore pass systems transcend multiple production levels, finger raises are used to funnel material into the system. Empirical evidence, from several mines, suggests that the use of finger raises often results in damage in the immediate vicinity of finger raise-ore pass junctions. Of particular concern is damage on the ore pass walls as a result of impact loads generated by material flowing through the fingers on to the ore pass walls. The severity of damage is directly related to the rock mass quality of the excavation walls, material properties of transiting ore and the ore pass-finger raise configuration. This paper examines the influence of different configurations aiming to develop strategies to minimize ore pass wall damage. To these purposes the Particle Flow Code was employed to undertake a series of numerical experiments. This involved dumping a batch of rock fragments, represented by a uniform distribution of disc-shaped particles, into a finger raise and allowed to flow into an ore pass. It has been clearly demonstrated that higher impact loads were generated when the angle of intersection between ore pass and finger raise was 140° to 145°. This configuration results in the most damage. The results of these numerical experiments were collaborated by observations at an underground mine in Canada.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{esmaieli-ijrmms10,

title = {Estimating geometrical and mechanical REV, based on synthetic rock mass models at Brunswick Mine},

author = {Kamran Esmaieli and John Hadjigeorgiou and Martin Grenon},

doi = {10.1016/j.ijrmms.2010.05.010},

year  = {2010},

date = {2010-06-17},

journal = {International Journal of Rock Mechanics and Mining Science},

volume = {47},

number = {6},

pages = {915-926},

abstract = {This paper uses a case study from Brunswick Mine in Canada to determine a representative elementary volume (REV) of a jointed rock mass in the vicinity of important underground infrastructure. The equivalent geometrical and mechanical property REV sizes were determined based on fracture systems modeling and numerical experiments on a synthetic rock mass. Structural data collected in massive sulphides were used to generate a large fracture system model (FSM), 40 m×40 m×40 m. This FSM was validated and subsequently sampled to procure 40 cubic specimens with a height to width ratio of 2 based on sample width from 0.05 to 10 m. The specimens were introduced into a 3D particle flow code (PFC3D) model to create synthetic rock mass (SRM) samples. The geometrical REV of the rock mass was determined based on the number of fractures in each sampled volume (P30) and the volumetric fracture intensity (P32) of the samples. The mechanical REV was estimated based on the uniaxial compressive strength (UCS) and elastic modulus (E) of the synthetic rock mass samples.



The REV size of the rock mass was determined based on a series of statistical tests. The T-test was used to assess whether the means of the samples were statistically different from each other and the F-test to compare the calculated variance. Finally, the coefficient of variation, for the synthetic rock mass geometrical and mechanical properties, was plotted against sample size. For this particular site the estimated geometrical REV size of the rock mass was 3.5 m×3.5 m×7 m, while the mechanical property REV size was 7 m×7 m×14 m. Consequently, for engineering purposes the largest volume (7 m×7 m×14 m) can be considered as the REV size for this rock mass.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Hadjigeorgiou2009,

title = {Stability analysis of vertical excavations in hard rock by integrating a fracture system into a PFC model},

author = {John Hadjigeorgiou and Kamran Esmaieli and Martin Grenon},

doi = {10.1016/j.tust.2008.10.002},

year  = {2009},

date = {2009-05-20},

journal = {Tunnelling and Underground Space Technology},

volume = {24},

number = {3},

pages = {296-308},

abstract = {This paper presents an implementation of a comprehensive engineering approach to the analysis of the stability of vertical excavations in rock. This approach relies in the generation of discrete fracture systems to better capture the structural complexity of the rock mass. The resulting fracture system is consequently linked into a distinct element stress analysis. The particle flow code was selected as it potentially allows greater flexibility in representing a fracture system. In the first example a 3D fracture system was linked into a 2D PFC model. Although this has allowed for an improved quantification of stress structure interaction it necessitated important simplifications which may not be necessarily appropriate. These have been overcome by providing a complete integration of a 3D fracture system to a 3D PFC model. This will potentially lead into a design tool that adequately account for the stress structure interaction on the stability of vertical or near vertical excavations in hard rock.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hadjigeorgiou-cim08,

title = {Observations of ore pass system performance at Brunswick Mine},

author = {John Hadjigeorgiou and Kamran Esmaieli and Richard Harrisson},

url = {http://www.cim.org/en/Publications-and-Technical-Resources/Publications/Proceedings/2008/2/PROC-2008-02-01/PROC-2008-02-27},

year  = {2008},

date = {2008-01-01},

journal = {CIM Journal},

volume = {3},

number = {5},

abstract = {Brunswick Mine employs an ore and waste pass system for material transfer. This paper reviews the evolution and performance ore pass systems over the years at the mine. In particular it addresses the influence of structure, stress and materials handling on the longevity of the employed ore passes. This is made possible by a comprehensive back analysis of several case studies. Finally, the practice at Brunswick is compared with other mining operations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}