Source parameters of seismic events potentially associated with damage in block 33/34 of the Kiirunavaara mine (Sweden)

Nordström, Emilia; Dineva, Savka; Nordlund, Erling

doi:10.1007/s11600-017-0066-1

Cited by 13 publications

(18 citation statements)

References 16 publications

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“…More than 1000 seismic events per day have been recorded in the whole mine during recent years. Most of the damaging seismic events investigated in block 33/34 of the mine from 2008 to 2013 were categorized as fault-slip type (Vatcher et al, 2014;Nordström et al, 2017). In the early history of underground mining in Kiirunavaara, the main stability problems occurred within the drift were gravity falls.…”

Section: 1mentioning

confidence: 99%

Investigation of Unstable Failure Potential of a Shear Slip Using DEM at an Underground Mine

Ma¹,

Zhang²

2021

Journal of Earth Sciences and Geotechnical Engineering

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Geological structures and discontinuities subjected to the perturbations posed by mining operations in underground mining can be re-activated and cause fault-slip rockbursts. This study investigates geomechanical stability in terms of shear slip behavior along discontinuities using 3DEC with focusing on sudden changes of shear stress and shear displacement. A direct shear test is performed using a continuously yielding joint model to examine the evolution of shear stress and shear displacement on this joint. Further, this continuously yielding joint model is applied in major discontinuities of an underground mine to examine whether an unstable shear slip behavior exists, which is represented by a significant shear stress decrease and a shear displacement increase. By referring to geological mapping of this mine, four cases are developed and each case is set up with one type of major discontinuities with identically simulated mining operations. Results imply that the amplitude of shear stress decrease and shear displacement increase along discontinuities substantially increases with the depth due to higher virgin stresses and mining-induced stresses at greater depths. The discontinuity parallel to the interface between footwall and orebody is the least safe case and subjects to the largest potential of triggering seismic events. Keywords: Shear slip behavior, Unstable failure, Mining-induced seismicity, Continuously yielding joint model, DEM.

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Section: 1mentioning

confidence: 99%

Investigation of Unstable Failure Potential of a Shear Slip Using DEM at an Underground Mine

Ma¹,

Zhang²

2021

Journal of Earth Sciences and Geotechnical Engineering

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“…Also, combined with microseismic monitoring results, Lebeau et al [9] analyzed the cause of a mining earthquake with 3.6 magnitudes in Meilai Bahe and established the relationships between the mine's seismic activity, stope stress levels, and elastic energy release rate. Nordström et al [10] analyzed the earthquake source parameters of 46 mining earthquakes which had induced by mining activities based on the Brune Model, the distribution laws of the different earthquake source parameters were calculated, and the relationships between the source parameters and the forms of hard rock damages were identified. In another related study, Konicek [11] introduced a process of using blasting methods to control mining earthquakes in the thick and hard roof areas of the Upper Silesian Coal Basin.…”

Section: Introductionmentioning

confidence: 99%

Mechanism and Prevention and Control of Mine Earthquake in Thick and Hard Rock Strata considering the Horizontal Stress Evolution of Stope

Zhang

Huang

et al. 2021

Shock and Vibration

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This study investigated the mechanism, prevention measures, and control methods for earthquake disasters typically occurring in mines with thick and hard rock strata. A mine stope with large faults and thick hard rock strata in Hebei Province was taken as the background study object. Then, theoretical analysis and numerical simulation methods were adopted in conjunction with field monitoring to explore how horizontal stress evolves in the thick and hard hanging roofs of such mines, potentially leading to mining earthquakes. Then, based on the obtained results, a mining design method was proposed to reduce the horizontal stress levels of earthquake mitigation. The results showed that, under the control of large faults, semiopen and semiclosed stopes with thick hard rock strata are formed, which cause influentially pressurized and depressurized zones during the evolution of the overburden movements and horizontal stress. It was determined that the stress concentrations mainly originated from the release and transfer of horizontal stress during the rock fractures and movements in the roof areas, which were calculated using a theoretical estimation model. The horizontal stress concentrations formed “counter torques” at both ends of the thick and hard strata, which prevented the support ending due to tensile failures. As a result, the limit spans were increased. This study proposed a mining strategy of using narrow working faces, strip mining processes, and reasonable mining speeds, which could effectively reduce horizontal stress concentrations and consequently prevent and control mining earthquakes. This study’s research results were successfully applied to the mining practices in working face 16103.

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“…Although Swedish mines also use the IMS magnitude scale, it is not calibrated for them. Events with magnitude roughly above 0 to 0.5 in Kiirunavaara Mine using this scale are considered capable of causing damage (Nordström et al 2017). Analysis of data for damaging events from Garpenberg Mine showed even very small events with M down to -1.9 can cause minor damage.…”

Section: Introductionmentioning

confidence: 99%

“…Magnitude-time distribution of the seismic event in three upper blocks in the Lappberget orebody fromHypocentre locations in Garpenberg Mine are routinely calculated by IMS using a procedure described inNordström et al (2017). The accuracy of the locations depends on the sensor coverage and especially the azimuthal coverage (Erguncu Güçlü 2016).…”

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confidence: 99%

Large seismic events (M > 0) in the Lappberget orebody, Garpenberg, Sweden: blast or non-blast-related?

Güçlü¹,

Dineva²,

Mozaffari³

et al. 2020

Proceedings of the Second International Conference on Underground Mining Technology

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The definition of large magnitude events for mining-induced seismicity highly depends on the general pattern of seismicity in the underground mine. The seismic system in the underground Garpenberg Mine, located in Sweden, was installed in June 2012. In total, 40,000 events were recorded by the end of 2018 with the largest event of magnitude M 2.3. The large seismic events in Garpenberg Mine are defined as the events with M > 0 and very large events with M > 1. This study is based on data from the Lappberget orebody from 2012 to the end of 2018. A seismically active zone was defined in the Lappberget orebody on the northeast side with approximately 90% of the seismicity. The larger magnitude events occurred mostly in this zone too. The large events occurred at depth above 1,000 m, and the so-called very large seismic events, above 750 m. The events in the upper levels, above 700 m, are characterised by comparatively lower apparent stress than the events below. It was found that 24 % of the large seismic events were triggered by production blasts within 24 hours and 150 m. Most of the blast-related large events occurred within two hours after blasting. Only a few large seismic events had intense aftershocks. The aftershock series lasts for around 10 hours and are within 150 m of the main shock. In case of more a complicated situation with blast relation and multiple large events, the aftershock series lasts more than 60 hours. Based on the observations made here, some simple rules were defined for closing mine areas after large seismic events (so-called re-entry protocol for large seismic events). The reasonable restriction after the large seismic event would be three hours with a 150 m radius from the hypocentre of the large seismic event. The duration might be extended depending on the pattern of the aftershock sequence, especially for the large seismic events that occurred after blasting. In this case, the procedure of re-entry protocol for post-blast sequences must be followed. The obtained information about the relation between the large events and blasting can be used also for the re-entry protocol after blasting.

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Source parameters of seismic events potentially associated with damage in block 33/34 of the Kiirunavaara mine (Sweden)

Cited by 13 publications

References 16 publications

Investigation of Unstable Failure Potential of a Shear Slip Using DEM at an Underground Mine

Investigation of Unstable Failure Potential of a Shear Slip Using DEM at an Underground Mine

Mechanism and Prevention and Control of Mine Earthquake in Thick and Hard Rock Strata considering the Horizontal Stress Evolution of Stope

Large seismic events (M > 0) in the Lappberget orebody, Garpenberg, Sweden: blast or non-blast-related?

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