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Nyberg, Ulf
Publications (10 of 57) Show all publications
Johansson, D., Nyberg, U., Stenman, U. & Schunnesson, H. (2019). Shock front curvature measurements of emulsion explosives. In: Roger Holmberg (Ed.), Proceedings of the 10th EFEE: . Paper presented at Helsinki Conference Proceedings 2019.
Open this publication in new window or tab >>Shock front curvature measurements of emulsion explosives
2019 (English)In: Proceedings of the 10th EFEE / [ed] Roger Holmberg, 2019Conference paper, Published paper (Refereed)
Abstract [en]

This paper will discuss a suggested methodology and data collection carried out within the EU-project SLIM    (Sustainable Low Impact solution for exploitation of small Mineral deposits based on advanced rock blasting and environmental technologies). The field work took place during 2017 at a test site near Stockholm, Sweden. This paper suggest a method measure the detonation front curvature and the velocity of detonation of explosives. The purpose for this is to increase the understanding of the detonation properties of emulsion explosives as used in many blasting operations around the world. In this study, the key parameters of the performance of the emulsion explosive are its non-ideal detonation front curvature and its velocity of detonation (VOD). The charge diameters have been varied Ø25mm up to Ø65 mm i.e. from nearly critical diameters for a steady detonation up to diameters used in mining/quarrying and tunneling. The suggested methodology also introduce a heavy and thick walled mortar as a confiner for the explosive. This to simulate similar conditions as in blasting in rock. Additional to the proposed methodology and set-up, a scheme to analyze and evaluate the measurements is also proposed.

National Category
Mineral and Mine Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-76528 (URN)978-0-9550290-6-6 (ISBN)
Conference
Helsinki Conference Proceedings 2019
Available from: 2019-10-28 Created: 2019-10-28 Last updated: 2019-11-27
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
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
Yi, C., Johansson, D. & Nyberg, U. (2018). Numerical modelling on short delay blast-induced fragmentation and vibration. Blasting and Fragmentation, 12(2), 105-116
Open this publication in new window or tab >>Numerical modelling on short delay blast-induced fragmentation and vibration
2018 (English)In: Blasting and Fragmentation, ISSN 1937-6359, Vol. 12, no 2, p. 105-116Article in journal (Refereed) Published
Abstract [en]

Blasting operations can fragment rock mass into smaller pieces and meanwhile induce vibration anddamage in remaining rock mass. A series of small-scale laboratory tests were carried out to investigatethe effects of short delay times on fragmentation. These tests were modeled using a coupledFEM-BPM-PBM model in the LS-DYNA code. In the model, the remaining rock is representedby a finite element model (FEM) and the rock to be blasted is represented by a bonded particlemodel (BPM). The detonation of explosives is described with a particle blast method (PBM). Thefragment size distribution was obtained with a code developed in Perl programming language. Theblast-induced vibration and damage in the remaining rock mass were evaluated. The results showthat the coupled FEM-BPM-PBM model can be employed to evaluate both fragmentation in theblasted domain and the blast-induced damage and vibration in the remaining rock mass.

Place, publisher, year, edition, pages
Cleveland: International Society of Explosives Engineers, 2018
Keywords
blasting, short delay, fragmentation, vibration, numerical modelling
National Category
Geotechnical Engineering
Research subject
Mining and Rock Engineering; Centre - Swedish Blasting Research Centre (SWEBREC)
Identifiers
urn:nbn:se:ltu:diva-73819 (URN)
Note

Validerad;2019;Nivå 1;2019-07-05 (johcin)

Available from: 2019-05-02 Created: 2019-05-02 Last updated: 2019-07-05Bibliographically approved
Yi, C., Lu, W., Zhang, P., Johansson, D. & Nyberg, U. (2016). Effect of imperfect interface on the dynamic response of a circular lined tunnel impacted by plane P-waves (ed.). Paper presented at . Tunnelling and Underground Space Technology, 51, 68-74
Open this publication in new window or tab >>Effect of imperfect interface on the dynamic response of a circular lined tunnel impacted by plane P-waves
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2016 (English)In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 51, p. 68-74Article in journal (Refereed) Published
Abstract [en]

A theoretical method for studying the dynamic response of a circular lined tunnel with an imperfectly bonded interface subjected to plane P-waves is presented in the paper. The wave function expansion method was used and the imperfect interface was modeled with a spring model. Two cases were discussed in the paper. In the first case rock is harder than the lining and vice-versa in the second case. The results indicated that the variation in the stiffness of the interface has much influence on the distribution of dynamic stress concentration factors (DSCF) in the rock and the lining. The imperfection of the interface has a more noticeable influence on the DSCF in the rock mass and the lining at high frequency incident wave's scenario than low frequency incident wave's scenario. The resonance scattering phenomena can be observed when the bond is extremely weak. Limiting cases were considered and a good agreement with the solutions available in the literature was obtained.

National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-15085 (URN)10.1016/j.tust.2015.10.011 (DOI)000367493200008 ()2-s2.0-84944346092 (Scopus ID)e8c88ef1-1254-4b5b-83b0-a0010b0b0d4a (Local ID)e8c88ef1-1254-4b5b-83b0-a0010b0b0d4a (Archive number)e8c88ef1-1254-4b5b-83b0-a0010b0b0d4a (OAI)
Note
Validerad; 2015; Nivå 2; 20151015 (chayir)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Yi, C., Zhang, P., Nordlund, E., Shirzadegan, S. & Nyberg, U. (2016). Numerical modelling of dynamic response of underground openings under blasting based on field tests (ed.). In: (Ed.), E. Nordlund, T.H. Jones and A. Eitzenberger (eds) (Ed.), Proceedings of the 8th International Symposium on Ground Support in Mining and Underground Construction: . Paper presented at Ground Support 2016 : 11/09/2016 - 14/09/2016.
Open this publication in new window or tab >>Numerical modelling of dynamic response of underground openings under blasting based on field tests
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2016 (English)In: Proceedings of the 8th International Symposium on Ground Support in Mining and Underground Construction / [ed] E. Nordlund, T.H. Jones and A. Eitzenberger (eds), 2016Conference paper, Published paper (Refereed)
Abstract [en]

In order to assess the capacity of ground support systems when subjected to dynamic loading, simulated rockburst tests by using blasting have been conducted at LKAB Kiirunavaara underground mine. In this paper, a numerical simulation for one of the field tests is conducted using LS-DYNA code to numerically investigate the effect of the different aspects of the charge design including the initiation point and the geometry on the test results. In the simulation, an explosive material model is used to model the detonation of explosive used in field tests and the Riedel-Hiermaier -Thoma (RHT) material model is used to model the dynamic response of the rock mass. The decoupling effect between the explosive and the wall of borehole is also taken into account in the model. The numerical results show a similar particle vibration pattern and a crack pattern to those of the field measurment. The effects of the position of the initiation point and the charge structure on the dynamic response of rock mass are also discussed. The results can be a reference for blast design for future field tests.

National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-61089 (URN)978-91-7583-804-5 (ISBN)
Conference
Ground Support 2016 : 11/09/2016 - 14/09/2016
Available from: 2016-12-15 Created: 2016-12-15 Last updated: 2018-04-17Bibliographically approved
Yi, C., Johansson, D. & Nyberg, U. (2016). Scattering of SH-waves by a shallow circular lined tunnel with an imperfect interface (ed.). In: (Ed.), E. Nordlund, T.H. Jones and A. Eitzenberger (eds) (Ed.), Proceedings of the 8th International Symposium on Ground Support in Mining and Underground Construction: . Paper presented at Ground Support 2016 : 11/09/2016 - 14/09/2016.
Open this publication in new window or tab >>Scattering of SH-waves by a shallow circular lined tunnel with an imperfect interface
2016 (English)In: Proceedings of the 8th International Symposium on Ground Support in Mining and Underground Construction / [ed] E. Nordlund, T.H. Jones and A. Eitzenberger (eds), 2016Conference paper, Published paper (Refereed)
Abstract [en]

The analytic solutions for the dynamic response of a shallow circular lined tunnel with an imperfectly bonded interface subjected to plane SH-waves are presented in the paper. Complex variable method was used and the imperfect interface was modelled with a linear spring model. The case that the rock is harder than the liner was investigated. The effects of the contact stiffness of the interface, the incident angle, the frequency of the incident wave and the depth of the tunnel were investigated. The results indicate when the frequency of incident waves is low, the variation of contact stiffness of the imperfect interface has a slight effect on the distribution of dynamic stress concentration factor (DSCF) in the rock mass but there is a significant effect on the distribution of DSCF in the liner. When the frequency of incident waves is high, the distribution of DSCF is complicated in the rock mass and in the liner. The variation of the depth of tunnel leads to the cyclical variation of DSCF. The incident angle significantly affects the distribution and value of DSCF. The phenomenon of resonance scattering can be observed when the bond of the interface is extremely weak

National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-61090 (URN)978-91-7583-804-5 (ISBN)
Conference
Ground Support 2016 : 11/09/2016 - 14/09/2016
Available from: 2016-12-15 Created: 2016-12-15 Last updated: 2018-04-17Bibliographically approved
Yi, C., Johansson, D., Nyberg, U. & Beyglou, A. (2016). Stress wave interaction between two adjacent blast holes (ed.). Paper presented at . Rock Mechanics and Rock Engineering, 49(5), 1803-1812
Open this publication in new window or tab >>Stress wave interaction between two adjacent blast holes
2016 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 49, no 5, p. 1803-1812Article in journal (Refereed) Published
Abstract [en]

Rock fragmentation by blasting is determined by the level and state of stress in the rock mass subjected to blasting. With the application of electronic detonators, some researchers stated that it is possible to achieve improved fragmentation through stress wave superposition with very short delay times. This hypothesis was studied through theoretical analysis in the paper. First, the stress in rock mass induced by a single-hole shot was analyzed with the assumptions of infinite velocity of detonation and infinite charge length. Based on the stress analysis of a single-hole shot, the stress history and tensile stress distribution between two adjacent holes were presented for cases of simultaneous initiation and 1 ms delayed initiation via stress superposition. The results indicated that the stress wave interaction is local around the collision point. Then, the tensile stress distribution at the extended line of two adjacent blast holes was analyzed for a case of 2 ms delay. The analytical results showed that the tensile stress on the extended line increases due to the stress wave superposition under the assumption that the influence of neighboring blast hole on the stress wave propagation can be neglected. However, the numerical results indicated that this assumption is unreasonable and yields contrary results. The feasibility of improving fragmentation via stress wave interaction with precise initiation was also discussed. The analysis in this paper does not support that the interaction of stress waves improves the fragmentation.

National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-10010 (URN)10.1007/s00603-015-0876-x (DOI)000374981500015 ()2-s2.0-84945156617 (Scopus ID)8c34946d-51ee-48da-a361-eeec0b0892a6 (Local ID)8c34946d-51ee-48da-a361-eeec0b0892a6 (Archive number)8c34946d-51ee-48da-a361-eeec0b0892a6 (OAI)
Note
Validerad; 2016; Nivå 2; 20151015 (chayir)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Ghosh, R., Zhang, Z. & Nyberg, U. (2015). Borehole instability in Malmberget Underground Mine (ed.). Paper presented at . Rock Mechanics and Rock Engineering, 48(4), 1731-1736
Open this publication in new window or tab >>Borehole instability in Malmberget Underground Mine
2015 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 48, no 4, p. 1731-1736Article in journal (Refereed) Published
National Category
Other Civil Engineering
Research subject
Operation and Maintenance; Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-6528 (URN)10.1007/s00603-014-0638-1 (DOI)000356884500030 ()2-s2.0-84933182948 (Scopus ID)4c09e7c7-19d4-4a51-85cb-e9eabc199620 (Local ID)4c09e7c7-19d4-4a51-85cb-e9eabc199620 (Archive number)4c09e7c7-19d4-4a51-85cb-e9eabc199620 (OAI)
Note
Validerad; 2015; Nivå 2; 20131230 (rajgho)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Yi, C., Nyberg, U. & Johansson, D. (2015). Parameter Determination of an Ignition and Growth Model from Emulsion Explosive Tests (ed.). In: (Ed.), (Ed.), 11th International Symposium on Rock Fragmentation by Blasting: FragBlast11. Paper presented at International Symposium on Rock Fragmentation by Blasting : 24/08/2015 - 25/08/2015 (pp. 585-589). Carlton VIC: The Australasian Institute of Mining and Metallurgy
Open this publication in new window or tab >>Parameter Determination of an Ignition and Growth Model from Emulsion Explosive Tests
2015 (English)In: 11th International Symposium on Rock Fragmentation by Blasting: FragBlast11, Carlton VIC: The Australasian Institute of Mining and Metallurgy, 2015, p. 585-589Conference paper, Published paper (Refereed)
Abstract [en]

Emulsion explosives are a common industrial explosive and have a non-ideal detonation behaviour. The detonation performance for a given product changes with the charge diameter, ground conditions, confinement and density. The burning process of an emulsion explosive has been modelled with an ignition and growth model in the LS-DYNA code. The parameters in the burning rate function are calibrated by the detonation velocities and the detonation front curvature radii from emulsion explosive tests. A Perl program was developed for an efficient estimation of the parameters, and the results show that the calibrated parameters can predict both detonation velocities and the detonation front curvatures.

Place, publisher, year, edition, pages
Carlton VIC: The Australasian Institute of Mining and Metallurgy, 2015
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-39883 (URN)ecdaf374-4af2-479c-a17d-18214db5c84e (Local ID)9781925100327 (ISBN)ecdaf374-4af2-479c-a17d-18214db5c84e (Archive number)ecdaf374-4af2-479c-a17d-18214db5c84e (OAI)
Conference
International Symposium on Rock Fragmentation by Blasting : 24/08/2015 - 25/08/2015
Note
Godkänd; 2015; 20150901 (chayir)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-04-17Bibliographically approved
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