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Publications (10 of 21) Show all publications
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
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
Show others...
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
Show others...
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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5872-5173

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