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Destress Blasting and Destress Drilling in Deep Hardrock Mining: Stress Management and Rockburst Mitigation
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.ORCID iD: 0000-0003-1014-0405
2026 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Deep underground hardrock mines face escalating rockburst risk as depth and stress increase. This thesis develops and demonstrates an integrated framework for stress management and rockburst mitigation that combines destress blasting and destress drilling with energy‐based indices, advanced monitoring, and geostatistics, tailored to Swedish deep mining conditions. Four objectives structure the work: (i) derive a design framework for destress blasting from six decades of international and Swedish practice; (ii) construct a quantitative evaluation methodology that integrates the strain energy storage coefficient (F), brittle shear ratio (BSR) and burst potential index (BPI) with fracture and seismic observations; (iii) execute and analyse a controlled field trial of destress drilling at Zinkgruvan mine; and (iv) develop a geostatistical concept (semi-variograms and kriging) to predict destress efficiency at unsampled locations with quantified uncertainty. 

The methodology adopted for the thesis study integrates structured literature and case-history analysis, numerical and energy-based reasoning, and in situ experimentation with high-resolution 3D laser scanning and cloud-to-cloud (C2C) analysis. The destress blasting component organises key rockmass, stress, and explosive parameters into a conceptual decision framework and design guidance; the evaluation framework specifies how F, BSR and BPI are computed and interpreted alongside monitored fracture and seismic responses; the Zinkgruvan mine practical field trial isolates the mechanical effect of uncharged inclined boreholes by keeping production-blast variables constant and quantifying geometric outcomes through C2C and volume-added metrics; and the geostatistical study shows how semi-variogram modelling and ordinary kriging can map performance indicators and their uncertainty to support risk-aware planning. 

Across case histories and supporting analyses, destress blasting is shown to be effective but highly localised and transient: stress relief typically extends only a few metres from the blast, and benefits decay rapidly as faces advance, necessitating continuous inclusion of destress features in each round within burst-prone zones. Mechanistic interpretation links reductions in boundary tangential stress and strain energy density to blast-induced fracture networks whose extent depends on rockmass brittleness and charging/timing choices; highly brittle rocks are both more burst-prone and more responsive when patterns and charge intensities are matched to site conditions. 

The practical Zinkgruvan mine field trial (depth of 1285 m) provides quantitative evidence that destress drilling stabilises development drifts. Rounds with 46 mm, 4 m destress drilling holes inclined at 20° (roof and shoulders) exhibited up to 2.5 m3 less scaled ‘volume added’ per metre of advance and a 20 – 30 % reduction in C2C profile standard deviation relative to non-destressed rounds, indicating lower overbreak and improved excavation profile control. It was observed that the first two rounds after a destressed round also performed comparably well, evidencing a short-range residual benefit that dissipates by the third non-destressed round, an operationally important finding for sequencing and cost-risk optimisation. 

The thesis study advances practice by: (i) organising destress blasting design considerations into a transferable, Swedish-context-aware framework; (ii) unifying energy indices (F, BSR, BPI) with fracture/deformation and seismic monitoring for quantitative evaluation at excavation scale; (iii) providing the first high-fidelity, field-validated C2C/volume-based assessment of destress drilling in a deep, burst-prone European mine; and (iv) introducing a geostatistical prediction concept that generates mine-wide efficiency maps with confidence bounds to reduce hazardous measurement campaigns and guide targeted data acquisition. 

The main conclusions and recommendations are that destress measures must be engineered and applied continuously in high-risk zones; design should be matched to rockmass brittleness and in situ stress; evaluation should jointly track energy indices, deformation/fracture, and seismicity; soft-scaling (where appropriate) practices should be integrated to minimise added volume; and geostatistical mapping and digital tools (3D scanning/C2C, IIoT) should underpin adaptive, feedback-driven planning.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2026.
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Keywords [en]
Destress blasting, Destress drilling, Rockburst mitigation, Deep hardrock mining, Stress management, Energy-based indices (F, BSR, BPI), Cloud-to-cloud (C2C) analysis, Geostatistics.
National Category
Geotechnical Engineering and Engineering Geology
Research subject
Mining and Rock Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-116337ISBN: 978-91-8048-985-0 (print)ISBN: 978-91-8048-986-7 (electronic)OAI: oai:DiVA.org:ltu-116337DiVA, id: diva2:2035960
Presentation
2026-03-27, A1545, Luleå University of Technology, Luleå, 10:10 (English)
Opponent
Supervisors
Projects
Destressing Project
Funder
Vinnova, 2020-04459Swedish Energy Agency, 2020-04459Swedish Research Council Formas, 2020-04459Available from: 2026-02-06 Created: 2026-02-05 Last updated: 2026-02-06Bibliographically approved
List of papers
1. Reflections on destress blasting for deep level hardrock mining: Key considerations for successful application of the techniques
Open this publication in new window or tab >>Reflections on destress blasting for deep level hardrock mining: Key considerations for successful application of the techniques
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2025 (English)In: Journal of the Southern African Institute of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 2411-9717, Vol. 125, no 6, p. 317-338Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Southern African Institute of Mining and Metallurgy, 2025
Keywords
destress blasting, hardrock mining, rockbursts management, numerical modelling, energy balance, seismicity
National Category
Mineral and Mine Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-114008 (URN)10.17159/2411-9717/3686/2025 (DOI)001522744800004 ()2-s2.0-105009878512 (Scopus ID)
Note

Validerad;2025;Nivå 2;2025-07-07 (u2);

Funder: Strategic Innovation Programme for the Swedish Mining and Metal Producing Industry (STRIM), which is a joint investment from VINNOVA, the Swedish Energy Agency and Formas, with additional in-kind contribution from Zinkgruvan Mining AB, LKAB, and Boliden (Ref. No.: 2020-04459);

Available from: 2025-07-07 Created: 2025-07-07 Last updated: 2026-02-05Bibliographically approved
2. Evaluating destress blasting for rock fracture and rockburst prediction in deep level hardrock mining
Open this publication in new window or tab >>Evaluating destress blasting for rock fracture and rockburst prediction in deep level hardrock mining
Show others...
2025 (English)In: Journal of the Southern African Institute of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 2411-9717, Vol. 125, no 6, p. 273-298Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Southern African Institute of Mining and Metallurgy, 2025
Keywords
destress blasting evaluation, deep-level hardrock mining, numerical modelling, rockburst prediction criteria, seismicity, geostatistical simulation, real-time monitoring (IIoT)
National Category
Mineral and Mine Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-114007 (URN)10.17159/2411-9717/3685/2025 (DOI)001522744800001 ()2-s2.0-105009949702 (Scopus ID)
Note

Validerad;2025;Nivå 2;2025-07-07 (u2);

Funder: Strategic Innovation Programme for the Swedish Mining and Metal Producing Industry (STRIM), which is a joint investment from VINNOVA, the Swedish Energy Agency, and Formas, with an additional in-kind contribution from Zinkgruvan Mining AB, LKAB, and Boliden (Ref. No.: 2020-04459);

Available from: 2025-07-07 Created: 2025-07-07 Last updated: 2026-02-05Bibliographically approved
3. Assessment of destress drilling as a rockburst management method for a stressed exploration drift at Zinkgruvan mine, Sweden
Open this publication in new window or tab >>Assessment of destress drilling as a rockburst management method for a stressed exploration drift at Zinkgruvan mine, Sweden
2025 (English)In: Results in Engineering (RINENG), ISSN 2590-1230, Vol. 26, article id 105398Article in journal (Refereed) Published
Abstract [en]

As mining progresses to greater depths, the challenges of high stress become more pronounced, often resulting in rockbursts that significantly impact deep underground mining operations. To address these challenges, Zinkgruvan mine in Sweden is testing destress drilling as a proactive measure to reduce the propensity for rockbursts and enhance the long-term stability of the mining drift, particularly in the roof and shoulders. Destress drilling holes, in this study, were drilled at 20° inclination on the periphery of the exploration drift and strategically placed ahead of development blasts. Laser scans of the drift were conducted before and after scaling, and the point cloud data was analysed using Cloud Compare software, with the Cloud-to-Cloud (C2C) algorithm employed to detect profile changes. This allowed for a comparison between blast rounds with and without destress drilling to assess the technique’s effectiveness. Results demonstrated that destress drilling reduced stress concentrations in the surrounding rockmass, as evidenced by reduced profile change. Blast rounds with destress drilling had up to 2.5 m3 less volume added per metre. C2C analysis showed 20 % to 30 % lower standard deviation and consistently lower mean deviation, indicating improved profile uniformity. These findings highlight the technical and operational benefits of destress drilling. 

Place, publisher, year, edition, pages
Elsevier, 2025
Keywords
Deep mining, High stress, Rockburst, Destress drilling, C2C, Point cloud analysis
National Category
Mineral and Mine Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-113024 (URN)10.1016/j.rineng.2025.105398 (DOI)001509084400003 ()2-s2.0-105007161729 (Scopus ID)
Note

Validerad;2025;Nivå 1;2025-06-09 (u2);

Full text: CC BY License;

Funder: Swedish Mining and Metal Producing Industry (STRIM), which is a joint investment from VINNOVA (The Swedish Governmental Agency for Innovation Systems), the Swedish Energy Agency and Formas with additional in-kind contribution from Zinkgruvan Mining, LKAB, and Boliden (Ref. No.: 2020-04459);

Available from: 2025-06-09 Created: 2025-06-09 Last updated: 2026-02-05Bibliographically approved
4. A conceptual study on the prediction of destress blasting efficiency using geostatistical approaches
Open this publication in new window or tab >>A conceptual study on the prediction of destress blasting efficiency using geostatistical approaches
2023 (English)In: Proceedings of the 15th International ISRM Congress 2023  on Rock Mechanics and Rock Engineering & 72nd Geomechanics Colloquium: Challenges in Rock Mechanics and Rock Engineering / [ed] Schubert, W.; Kluckner, A., Austrian Society for Geomechanics , 2023, p. 487-492Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Austrian Society for Geomechanics, 2023
National Category
Geotechnical Engineering and Engineering Geology Geosciences, Multidisciplinary
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-102997 (URN)
Conference
15th International ISRM Congress & 72nd Geomechanics Colloquium 2023, Salzburg, Austria, October 9-14, 2023
Note

ISBN for host publication: 978-3-9503898-3-8

Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2026-02-05Bibliographically approved

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