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Nordström, E., Dineva, S. & Nordlund, E. (2020). Back Analysis of Short-Term Seismic Hazard Indicators of Larger Seismic Events in Deep Underground Mines (LKAB, Kiirunavaara Mine, Sweden). Pure and Applied Geophysics, 177(2), 763-785
Open this publication in new window or tab >>Back Analysis of Short-Term Seismic Hazard Indicators of Larger Seismic Events in Deep Underground Mines (LKAB, Kiirunavaara Mine, Sweden)
2020 (English)In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 177, no 2, p. 763-785Article in journal (Refereed) Published
Abstract [en]

Back analysis for evaluation of the merits of the short-term seismic hazard indicators (precursors) used in the mines and their potential application for early warning was carried out for fourteen seismic events that potentially caused damage in Kiirunavaara Mine, Sweden, selected according to our designed criteria. Five short-term hazard indicators: Seismic Activity Rate (SAR), Cumulative Seismic Moment (CSM), Energy Index (EI), Cumulative Apparent Volume (CAV) and Seismic Apparent Stress Frequency (ASF) were tested. The behaviour of the indicators was studied using the parameters of all seismic events within a sphere around the hypocenter location of the analyzed seismic source within one month before the main (damaging) event. The size of the sphere equals the estimated radius of the analyzed seismic source (area of inelastic deformation). mXrap software (Australian Centre for Geomechanics) was used for data visualization, manipulation, analysis and extraction. The results from the main analysis showed a good agreement between the expected and actual behaviour of the SAR, CSM and CAV indicators. In overall, CSM and CAV ranked the highest positive/expected behaviour followed by SAR (Table 3). The EI and ASF ranked lowest and showed to be sensitive to the number of events within the source sphere. The rate of false warnings and missed warnings was also investigated for the 25 days-long period before the damaging events. A similar trend was observed as for the main analysed event. The results from this study can be used for further improvement of the short-term hazard estimations and early warning system in deep underground mines.

Place, publisher, year, edition, pages
Springer, 2020
Keywords
Induced seismicity in mines, seismic hazards, rockbursts, mine seismology
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-76653 (URN)10.1007/s00024-019-02352-8 (DOI)000511540200011 ()2-s2.0-85074864360 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-03-10 (johcin)

Available from: 2019-11-10 Created: 2019-11-10 Last updated: 2020-03-10Bibliographically approved
Yi, C., Nordlund, E., Zhang, P., Warema, S. & Shirzadegan, S. (2020). Numerical modeling for a simulated rockburst experiment using LS-DYNA. Underground Space
Open this publication in new window or tab >>Numerical modeling for a simulated rockburst experiment using LS-DYNA
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2020 (English)In: Underground Space, ISSN 2467-9674Article in journal (Refereed) Epub ahead of print
Abstract [en]

Ground support systems are commonly used to mitigate the potential consequences of rockburst in burst prone mines. To assess the capacity of ground support systems when subjected to dynamic loading, simulated rockburst tests using blasting were conducted at the Kiruna Mine. In this study, a numerical simulation for one of the field tests was conducted using the LS-DYNA code to investigate the dynamic response of the ground support systems including shotcrete and rockbolts. The numerical results showed a similar particle vibration pattern and a crack pattern to those of the field measurements. The effects of the detonator position and the charge configuration on the dynamic response of ground support systems are also discussed. Numerical results indicated that the peak particle vibrations on the tested panel increase along the direction of detonation propagation. It is difficult to use different charge concentrations in one borehole to investigate the effect of different dynamic loads on the dynamic response of support systems. Numerical results also indicated that 2D numerical modeling for simulated rockburst experiments could overestimate the dynamic response of ground support systems.

Place, publisher, year, edition, pages
Tongji University and Tongji University Press., 2020
Keywords
Simulated rockburst experiments, Ground support systems, Numerical modeling
National Category
Geotechnical Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-77828 (URN)10.1016/j.undsp.2019.11.002 (DOI)2-s2.0-85084697682 (Scopus ID)
Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-05-28
Jones, T., Nordlund, E. & Wettainen, T. (2019). Mining-Induced Deformation in the Malmberget Mine. Rock Mechanics and Rock Engineering, 52(6), 1903-1916
Open this publication in new window or tab >>Mining-Induced Deformation in the Malmberget Mine
2019 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 52, no 6, p. 1903-1916Article in journal (Refereed) Published
Abstract [en]

The Norra Alliansen orebody of the Malmberget sublevel caving mine consists of iron ore interspersed with biotite schist and granitic inclusions. The schist is squeezed between the ore and the host rock and in direct contact with the ore along the majority of the length of the footwall. The schist exhibits high deformation when exposed to stress. SMART cable bolt roof deformation measurements are re-analyzed to draw conclusions regarding the patterns of deformation in the mine. Each bolt’s head is placed at the origin of a spherical coordinate system and the radius and inclination angle between the bolt and every production blast occurring during the bolt’s recorded lifetime are calculated. The deformation experienced by each instrument is investigated by comparing the long-term recorded movements with the developed geometric variables. Patterns of deformation magnitude and rate are found with respect to production-blast distance and inclination angle, instrument location, rock quality designation, and likely mining-induced stresses. Results show that deformation magnitude tends to be higher when driven by production blasting occurring on the production level above the instrumentation when accounting for the effects of distance, but average deformation magnitude for very-near production blasts tends to be higher than that for production blasts occurring directly above the instrument. Correlations also exist between the measured RQD, estimated rockmass parameters, and the measured deformation. Empirical evidence allows the identification of six scenarios which account for 91% of the recorded high-deformation-rate events. These scenarios help determine which production activities are most likely to cause high deformation rates.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Roof deformation, Mining-induced deformation, Sublevel caving, Instrumented bolts, Mining, Ground control
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-72687 (URN)10.1007/s00603-018-1716-6 (DOI)000468991100019 ()2-s2.0-85059776177 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-11 (johcin)

Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-06-20Bibliographically approved
Idris, M. A. & Nordlund, E. (2019). Probabilistic-Based Stope Design Methodology for Complex Ore Body with Rock Mass Property Variability. Journal of mining science, 55(5), 743-750
Open this publication in new window or tab >>Probabilistic-Based Stope Design Methodology for Complex Ore Body with Rock Mass Property Variability
2019 (English)In: Journal of mining science, ISSN 1062-7391, E-ISSN 1573-8736, Vol. 55, no 5, p. 743-750Article in journal (Refereed) Published
Abstract [en]

This paper presents a probabilistic approach for optimizing stope design methodology whiletaking into consideration the variability in the rock mass properties. For this study, a complex orebody in aCanadian mine was used. Because of the variability in the rock mass properties of the orebody, it was notpossible to determine precisely, the values of geotechnical design input parameters and hence the need toutilize a probabilistic approach. Point Estimate Method (PEM), a probabilistic tool, was incorporated intonumerical analysis using FLAC3D to study the deformation magnitudes of various stope geometries todetermine the optimal stope geometry with a minimum ground control problem. Results obtained for thedistribution of the wall deformations and the floor heaves for each option of the stope geometry werecompared to select the best geometry to achieve the optimum stability condition. The methodologypresented in this study can be helpful in the process of underground mine planning and optimization incomplex orebody.

Place, publisher, year, edition, pages
Russia: Springer, 2019
Keywords
Complex orebody, probabilistic approach, rock mass variability, stope geometry, point estimate method
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-78834 (URN)10.1134/S1062739119056112 (DOI)2-s2.0-85083678476 (Scopus ID)
Note

Godkänd;2020;Nivå 0;2020-05-11 (alebob)

Available from: 2020-05-10 Created: 2020-05-10 Last updated: 2020-05-11Bibliographically approved
Zhang, P., Nordlund, E., Swan, G. & Yi, C. (2019). Velocity Amplification of Seismic Waves Through Parallel Fractures Near a Free Surface in Fractured Rock: A Theoretical Study. Rock Mechanics and Rock Engineering, 52(1), 199-213
Open this publication in new window or tab >>Velocity Amplification of Seismic Waves Through Parallel Fractures Near a Free Surface in Fractured Rock: A Theoretical Study
2019 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 52, no 1, p. 199-213Article in journal (Refereed) Published
Abstract [en]

To determine the dynamic demand for support design under rockburst conditions, one of the most important issues is the prediction of ground motion parameters at the site of interest. Field monitoring has shown that the peak ground motion at the surface of an excavation in fractured rock is preferentially amplified compared to the motion in solid rock at a similar distance from the source. However, the traditional scaling laws used in rock support design do not account for the effect of free surface (excavation) and fracturing of rock. Recent studies have shown that high ground motion might be generated when a seismic wave crosses through fractures near a free surface in fractured rocks which is very complex and is not well understood. In this paper, particle velocity amplification was theoretically studied by investigating the dynamic interaction between seismic wave and multiple fractures near a free surface using the method of characteristics and the displacement discontinuity model. A harmonic load was applied on a model with a fractured zone near a free surface to investigate this phenomenon. After the harmonic wave propagated normally through multiple parallel fractures, the velocity amplification factor (VAF) was calculated as a function of the ratio of the magnitude of the peak particle velocity at the free surface of the model to the peak input velocity. The VAF can be as high as 3.77 and varies depending on the state of the fractured rock and the characteristics of the seismic wave. Parameter studies were conducted to investigate the effects of seismic load and multiple fractures on wave propagation, especially in terms of the wave frequency, the fracture spacing, the number of fractures and the stiffness of fractures. The results have proved that the interaction of the seismic wave and multiple fractures near the free surface strongly influences the ground motion. Quantitative relationships between the various influential factors and the corresponding VAF were developed. It is anticipated that such relationships can provide criteria to improve the current design procedures and help mining engineers to improve their rock support practice for rockburst-prone areas.

Place, publisher, year, edition, pages
Vienna: Springer, 2019
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-70965 (URN)10.1007/s00603-018-1589-8 (DOI)000456673000013 ()2-s2.0-85053438929 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-25 (inah)

Available from: 2018-09-25 Created: 2018-09-25 Last updated: 2019-04-24Bibliographically approved
Idris, M. A. & Nordlund, E. (2019). ВЕРОЯТНОСТНАЯ МЕТОДИКА ПРОЕКТИРОВАНИЯ ОЧИСТНЫХ ЗАБОЕВ ДЛЯ СЛОЖНЫХ РУДНЫХ ТЕЛ С ИЗМЕНЯЮЩИМИСЯ СВОЙСТВАМИ ПОРОДНОГО МАССИВА. Физико-технические проблемы разработки полезных ископаемых (5), 56-62
Open this publication in new window or tab >>ВЕРОЯТНОСТНАЯ МЕТОДИКА ПРОЕКТИРОВАНИЯ ОЧИСТНЫХ ЗАБОЕВ ДЛЯ СЛОЖНЫХ РУДНЫХ ТЕЛ С ИЗМЕНЯЮЩИМИСЯ СВОЙСТВАМИ ПОРОДНОГО МАССИВА
2019 (Russian)In: Физико-технические проблемы разработки полезных ископаемых, ISSN 0015-3273, no 5, p. 56-62Article in journal (Refereed) Published
Abstract [ru]

Представлен вероятностный подход для оптимизации методики расчета параметров забоя с учетом изменчивости свойств горного массива на примере сложного рудного месторождения в Канаде. Для точного определения значений входящих геотехнических параметров использован вероятностный метод PEM (метод точечной оценки) в совокупности с численным анализом и программным обеспечением FLAC3D. Определены деформации выработок с различной геометрией и оптимальные параметры выработки для минимизации проблем управления состоянием массива. Полученные результаты по распределению деформаций стенок и почвы выработок анализировались для каждого варианта с целью выбора их наилучшей геометрии и достижения оптимальной устойчивости

Place, publisher, year, edition, pages
Издательство СО РАН, 2019
Keywords
Complex orebody, probabilistic approach, rock mass variability, stope geometry, point estimate method, Сложное рудное тело, вероятностный метод, изменчивость породного массива, геометрия выработки, метод точечной оценки
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-78881 (URN)10.15372/FTPRPI20190507 (DOI)
Note

Godkänd;2020;Nivå 0;2020-05-14 (alebob)

Available from: 2020-05-14 Created: 2020-05-14 Last updated: 2020-05-14Bibliographically approved
Petropoulos, N., Wimmer, M., Johansson, D. & Nordlund, E. (2018). Compaction of confining materials in pillar blast tests. Rock Mechanics and Rock Engineering, 51(6), 1907-1919
Open this publication in new window or tab >>Compaction of confining materials in pillar blast tests
2018 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 51, no 6, p. 1907-1919Article in journal (Refereed) Published
Abstract [en]

Two confined pillar tests were conducted at the Kiirunavaara mine to investigate the degree of compaction of three materials, i.e., 0–32-mm backfilled material, a blend of ore and waste material and caved material. Two blastholes were drilled parallel to each pillar wall, and several measurement holes were drilled in between the blastholes through each pillar. Both the measurement holes and backfilled materials, except the caved material, were instrumented. Two types of measurements were taken: dynamic measurements with accelerometers, and static measurements which considered the location of the instrumentation pre- and post-blast. Dynamic measurements involved the burden movement and the confining material behavior, and static measurements contained the final location of sensors inside and the angle of repose of the confining material. The results showed that the size distribution of the confining material affects its behavior under dynamic loading. The backfilled materials showed an apparent cohesion forming an agglomeration on the surface of the blasted burden. The burden moved as one slab due to simultaneous detonation. A gap was formed between the blasted burden and the new face. This gap was partially filled with burden erosion material which was finer fragmented than the blasted burden material.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Compaction, burden movement, pillar tests, sublevel caving, confined blasting
National Category
Mineral and Mine Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-67850 (URN)10.1007/s00603-018-1447-8 (DOI)000433195900016 ()2-s2.0-85047517598 (Scopus ID)
Projects
Improved understanding of sublevel blasting – Determination of the extent of the compacted zone, its properties and the effects on caving
Note

Validerad;2018;Nivå 2;2018-06-01 (rokbeg)

Available from: 2018-03-06 Created: 2018-03-06 Last updated: 2018-08-27Bibliographically approved
Petropoulos, N., Mihaylov, D., Johansson, D. & Nordlund, E. (2017). A Suggested Method for the Study of Crushed Aggregate Response to Dynamic Compaction. The Electronic journal of geotechnical engineering, 22(02), 387-406
Open this publication in new window or tab >>A Suggested Method for the Study of Crushed Aggregate Response to Dynamic Compaction
2017 (English)In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 22, no 02, p. 387-406Article in journal (Refereed) Published
Abstract [en]

Soil improvement by dynamic compaction has been extensively used all around the world in large civil engineering projects. Limited number of laboratory tests has been conducted to study the behavior of soil material under dynamic loading. A suggested method is presented in this paper which includes a new laboratory apparatus and experimental procedure as well as data analysis. The suggested impact machine is a drop hammer type machine, it can host up to 37.5 mm particle size in a coarse-grained aggregate matrix independent of its conditions, i.e. saturated or unsaturated, it is also flexible in terms of weight and size of the drop hammer and the mold. The machine is equipped with accelerometers for continuous monitoring of the sample’s behavior during impact. The experimental procedure shows the steps for conducting consistent dynamic compaction tests. It also describes how the measurements should be conducted. These measured quantities correspond to key parameters such as density, angle of repose and compaction. Finally, a case example demonstrates the function of the machine and the analysis of the recorded data.

Place, publisher, year, edition, pages
Mete Öner, 2017
Keywords
Dynamic compaction, impact tests, experimental apparatus, soil behavior, confined blasting
National Category
Mineral and Mine Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-61643 (URN)
Projects
Improved understanding of sublevel blasting – Determination of the extent of the compacted zone, its properties and the effects on caving
Note

Validerad; 2017; Nivå 1; 2017-02-15 (andbra)

Available from: 2017-01-26 Created: 2017-01-26 Last updated: 2018-11-20Bibliographically approved
Petropoulos, N., Johansson, D. & Nordlund, E. (2017). Crushed aggregate response upon impact in dry and wet conditions. Journal of Earth Sciences and Geotechnical Engineering, 7(3), 1-22
Open this publication in new window or tab >>Crushed aggregate response upon impact in dry and wet conditions
2017 (English)In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 7, no 3, p. 1-22Article in journal (Refereed) Published
Abstract [en]

This paper presents results from a series of impact tests upon coarse-grained crushed aggregate. The material has been evaluated for two conditions, i.e. dry and wet (pendular state). Three main sets of test configurations were used with respect to compactive effort (low, medium and high) which was defined by the impact velocity of a drop hammer. Three accelerometers were installed in an impact machine to measure deceleration of the drop hammer and accelerations in the tested material at three different locations. The studied parameters were density, compaction, angle of repose, critical angle and particle size distribution. The results showed that the wet material gives larger density as well as critical angle. However, there was no discernible change in particle size distribution.

Place, publisher, year, edition, pages
ScienPress Ltd, 2017
Keywords
Impact tests, granular material, aggregate, compaction, wet material, dry material
National Category
Mineral and Mine Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-62844 (URN)
Projects
Improved understanding of sublevel blasting – Determination of the extent of the compacted zone, its properties and the effects on caving
Note

Validerad; 2017; Nivå 1; 2017-04-04 (andbra)

Available from: 2017-04-03 Created: 2017-04-03 Last updated: 2018-11-15Bibliographically approved
Saiang, D. & Nordlund, E. (2017). Numerical Analyses of Field Monitoring in Stope J10-3 at Kristineberg Mine. Luleå: Luleå University of Technology
Open this publication in new window or tab >>Numerical Analyses of Field Monitoring in Stope J10-3 at Kristineberg Mine
2017 (English)Report (Refereed)
Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2017. p. 61
Series
Technical report / Luleå University of Technology, ISSN 1402-1536
National Category
Engineering and Technology Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-62761 (URN)978-91-7583-857-1 (ISBN)
Available from: 2017-03-28 Created: 2017-03-28 Last updated: 2018-04-16Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9766-0106

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