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Publications (10 of 24) Show all publications
Yi, C., Nyberg, U., Johansson, D. & Schunnesson, H. (2020). Ignition and Growth Reactive Flow Model for Aluminized Emulsion Explosive. In: : . Paper presented at 46th Annual Conference on Explosives and Blasting Technique.
Open this publication in new window or tab >>Ignition and Growth Reactive Flow Model for Aluminized Emulsion Explosive
2020 (English)Conference paper, Published paper (Refereed)
Abstract [en]

To investigate the non-ideal detonation properties of aluminized emulsion explosive, a series of tests for an emulsion explosive with 5% aluminum powder additive were carried out with mortar confinement. The velocity of detonation (VoD) and the curvature of the detonation front for different charge diameters were obtained from the tests with a high-speed camera. The burning process of the aluminized emulsion explosive has been modelled with the ignition and growth (I&G) flow model in the LS-DYNA code. A routine based on the optimization program LS-OPT code was developed to identify the parameters in the burning rate function with the detonation velocities and the front curvature radii from two tests. A Perl code was implemented in the routine and was used to calculate the VoD, fit the detonation front and obtain the detonation front curvature radii.  The calibrated parameters were used to predict the VoDs and the detonation front curvature radii for the rest cases. The results indicate that both the VoDs and the detonation front curvature radii from the numerical modelling are in good agreement with the experimental results. The numerical results also indicate that the variety of the burn fraction and the peak pressure with the change of charge diameters is reasonable with the calibrated parameters.

National Category
Geotechnical Engineering
Identifiers
urn:nbn:se:ltu:diva-77624 (URN)
Conference
46th Annual Conference on Explosives and Blasting Technique
Available from: 2020-02-03 Created: 2020-02-03 Last updated: 2020-03-11
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
Yi, C., Johansson, D., Schunnesson, H. & Åhlin, H. (2019). Numerical study of the impact of joints on rock fragmentation by blasting. In: : . Paper presented at EFEE 10th World Conference on Explosives and Blasting.
Open this publication in new window or tab >>Numerical study of the impact of joints on rock fragmentation by blasting
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Rock masses consist essentially of intact rock and discontinuities such as joints. Blasting is mostly used method for the rock excavation. To investigate the effects of joints on the fragmentation by blasting, three models with different joint patterns and one model without joint were created in the LS-DYNA code. In these models, a bonded particle model was used to represent the rock to be blasted, a finite element model was adopted to model the remaining rock mass and a particle blast model was employed to describe the detonation of explosives. To validate the contact model for joints, the fragmentation pattern and the individual particle motion from two single borehole shot models with and without joints were compared. The numerical results indicated that the existence of joints has a significant effect on fragmentation and vibration. The models with joints produced finer fragmentation compared to the model without joints in the paper. 

Keywords
blasting, joints, fragmentation
National Category
Geotechnical Engineering
Identifiers
urn:nbn:se:ltu:diva-76089 (URN)978-0-9550290-6-6 (ISBN)
Conference
EFEE 10th World Conference on Explosives and Blasting
Available from: 2019-09-23 Created: 2019-09-23 Last updated: 2019-12-17
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
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. & 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
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., 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
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
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5872-5173

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