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Publications (10 of 41) Show all publications
Ittner, H., Olsson, M., Johansson, D. & Schunnesson, H. (2019). Multivariate evaluation of blast damage from emulsion explosives in tunnels excavated in crystalline rock. Tunnelling and Underground Space Technology, 85, 331-339
Open this publication in new window or tab >>Multivariate evaluation of blast damage from emulsion explosives in tunnels excavated in crystalline rock
2019 (English)In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 85, p. 331-339Article in journal (Refereed) Published
Abstract [en]

Blast damage in tunnels is usually regulated in Swedish infrastructure contracts as it can influence the quality and lifecycle cost for tunneling projects. The topic is important for underground constructions with a long operation period such as tunnels for public transport, permanent access tunnels in mines or underground repositories for nuclear waste. This paper aims to evaluate the influence of design and geology variables on the resulting blast fracture length and frequency by means of multivariate data analysis. The analysis was based on data from five field investigations carried out at tunnel sites in Sweden and Finland where emulsion explosives were used. Data was compiled and analyzed using Principal Component Analysis (PCA). Charge concentration was found to be the most influential design variable and hole spacing had limited influence on blast fracturing. Results from the PCA suggest that blast fractures length could be dependent also on geology and natural fractures. Three main groups of fracture patterns were identified, one group with relatively few and short blast fractures, a group with several longer blast fractures and a group with few or a single long blast fracture. The result shows differences in fracture length between the column and bottom charge part of the contour holes, with blast fracture lengths up to approx. 40 cm for the column charge and up to approx. 60 cm for the bottom charge.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Blasting, Blast damage, Emulsion explosives, Mechanized charging, Principal Component Analysis
National Category
Geotechnical Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-67454 (URN)10.1016/j.tust.2018.12.021 (DOI)000457512000031 ()2-s2.0-85059473074 (Scopus ID)
Funder
Rock Engineering Research Foundation (BeFo)
Note

Validerad;2019;Nivå 2;2019-01-10 (svasva)

Available from: 2018-02-01 Created: 2018-02-01 Last updated: 2019-04-23Bibliographically approved
Yi, C., Nyberg, U. & Johansson, D. (2018). Calibration and Validation of Reactive Flow Model Parameters for an emulsion explosive. In: : . Paper presented at 12th International Symposium on Rock Fragmentation by Blasting, Fragblast 12, Luleå, Sweden on June 9-15.
Open this publication in new window or tab >>Calibration and Validation of Reactive Flow Model Parameters for an emulsion explosive
2018 (English)Conference paper, Published paper (Refereed)
National Category
Engineering and Technology Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-69773 (URN)
Conference
12th International Symposium on Rock Fragmentation by Blasting, Fragblast 12, Luleå, Sweden on June 9-15
Available from: 2018-06-21 Created: 2018-06-21 Last updated: 2018-06-27
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
Yi, C., Johansson, D. & Greberg, J. (2018). Effects of in-situ stresses on the fracturing of rock by blasting. Computers and geotechnics, 104, 321-330
Open this publication in new window or tab >>Effects of in-situ stresses on the fracturing of rock by blasting
2018 (English)In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 104, p. 321-330Article in journal (Refereed) Published
Abstract [en]

Blasting is widely applied in deep rock excavation. The effect of in-situ stresses on the fracturing of rock due to blasting was investigated. A theoretical model was used to explain the effect mechanism of in-situ stresses on crack propagation due to blasting. Four cases with different in-situ stress conditions were numerically investigated. The numerical results indicate that the crack propagation is governed by the blast load in the vicinity of the blasthole while the high in-situ stresses can influence the crack propagation in the far-field. The crack propagation trends towards the direction in which the high initial pressure is applied.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Blasting, In-situ stresses, Crack propagation
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering; Centre - Swedish Blasting Research Centre (SWEBREC)
Identifiers
urn:nbn:se:ltu:diva-67060 (URN)10.1016/j.compgeo.2017.12.004 (DOI)000449125200029 ()2-s2.0-85038407140 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-19 (johcin)

Available from: 2017-12-19 Created: 2017-12-19 Last updated: 2019-03-26Bibliographically approved
Yi, C., Johansson, D. & Nyberg, U. (2018). Numerical investigation for timing effects on fragmentation based on a coupled FEM-BPM-PBM model. In: : . Paper presented at 12th International Symposium on Rock Fragmentation by Blasting, Fragblast 12, Luleå, Sweden on June 9-15, 2018.
Open this publication in new window or tab >>Numerical investigation for timing effects on fragmentation based on a coupled FEM-BPM-PBM model
2018 (English)Conference paper, Published paper (Refereed)
National Category
Engineering and Technology Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-69770 (URN)
Conference
12th International Symposium on Rock Fragmentation by Blasting, Fragblast 12, Luleå, Sweden on June 9-15, 2018
Available from: 2018-06-21 Created: 2018-06-21 Last updated: 2018-06-27
Danielsson, M., Johansson, D. & Schunnesson, H. (2018). The Influence of Blast Fragmentation on Loadability in Sublevel Caving. In: Kevin Hachmeister (Ed.), Proceedings of the forty-forurth annual conference on explosives and blasting technique: . Paper presented at 44th Annual Conference on Explosives and Blasting Technique, San Antonio, Texas, Jan. 28–31 2018.
Open this publication in new window or tab >>The Influence of Blast Fragmentation on Loadability in Sublevel Caving
2018 (English)In: Proceedings of the forty-forurth annual conference on explosives and blasting technique / [ed] Kevin Hachmeister, 2018Conference paper, Published paper (Refereed)
Abstract [en]

In sublevel caving, blasted material flows gravitationally into the drawpoint from above in a periodical manner. This type of flow behavior entails muck pile conditions that are variable along the course of extraction. The effect of this variability on the LHD (Load-Haul-Dump) operation in terms of loading efficiency and ability to undermine the blasted ring is not fully understood as of today. This paper presents results from a field test in LKABs Malmberget mine in Sweden, where the influence of fragmentation on the loading operation has been studied in detail. Drawpoint filming was conducted for extraction of two rings equivalent of roughly 10000 metric tons (~9842 long tons) of material each. The analysis includes fragmentation measurements, muck pile classification, and general estimations in terms of loadability. Further, an evaluation of LHD machines from two different manufacturers was conducted to identify and highlight differences. The results show that fragmentation, muck pile compactness, and flow characteristics are all interdependent. Flow disturbances and the subsequent loading of compacted fine material in the back of the ring have been identified as the main reason for occurring problems and prolonged digging times. However, the ability to sufficiently undermine the blasted ring has been identified to primarily depend on digging depth which is only observed to be high during flow disturbances. An absence of flow disturbances seem to promote high loading efficiency but simultaneously limit the maximum digging depth. A mid-range particle size distribution with a low amount of fines has proven beneficial for overall loading efficiency. The various LHDs employed showed significant variations in terms of ability to handle difficult loading situations (e.g. compactness, boulders, etc.).

National Category
Other Engineering and Technologies not elsewhere specified Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-70536 (URN)
Conference
44th Annual Conference on Explosives and Blasting Technique, San Antonio, Texas, Jan. 28–31 2018
Available from: 2018-08-22 Created: 2018-08-22 Last updated: 2018-08-28
Yi, C., Sjöberg, J., Johansson, D. & Petropoulos, N. (2017). A numerical study of the impact of short delays on rock fragmentation. International Journal of Rock Mechanics And Mining Sciences, 100, 250-254
Open this publication in new window or tab >>A numerical study of the impact of short delays on rock fragmentation
2017 (English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 100, p. 250-254Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Geotechnical Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-66397 (URN)10.1016/j.ijrmms.2017.10.026 (DOI)000418009400025 ()
Note

Validerad;2017;Nivå 2;2017-11-07 (andbra)

Available from: 2017-11-06 Created: 2017-11-06 Last updated: 2018-04-17Bibliographically 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
Yi, C., Sjöberg, J. & Johansson, D. (2017). Numerical modelling for blast-induced fragmentation in sublevel caving mines. Tunnelling and Underground Space Technology, 68, 167-173
Open this publication in new window or tab >>Numerical modelling for blast-induced fragmentation in sublevel caving mines
2017 (English)In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 68, p. 167-173Article in journal (Refereed) Published
Abstract [en]

The flow behavior of the ore and waste significantly affect the dilution in sublevel caving (SLC) mines. Drill and blast issues are identified as having a substantial impact upon SLC material flow. In the paper, blast-induced fragmentation in SLC was numerically investigated using the LS-DYNA code. A method was presented to evaluate fragmentation based on the damage description and a fragment identification routine implemented in the LS-PREPOST (a pre- and post-processing tool of LS-DYNA). The effects of the delay time and the primer position on fragmentation were investigated. The results indicated that a long delay time gives a finer fragmentation for the cases discussed in the paper. The results also showed that the middle primer and the top primer in SLC can give a fine fragmentation. The limitations of numerical modelling were also discussed.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-63721 (URN)10.1016/j.tust.2017.05.030 (DOI)000406988300015 ()2-s2.0-85019988601 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-06-05 (andbra)

Available from: 2017-06-05 Created: 2017-06-05 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5165-4229

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