Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Analysis of Excavation Damage, Rock Mass Characterisation and Rock Support Design using Drilling Monitoring
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.ORCID iD: 0000-0003-1923-044x
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Prior to an underground excavation a site investigation is carried out. This includes reviewing and analysing existing data, field data collected through outcrop mapping, drill core logging and geophysical investigations. These data sources are combined and used to characterise, quantify and classify the rock mass for the tunnel design process and excavation method selection.

Despite the best approaches used in a site investigation, it cannot reveal the required level of detail. Such gaps in information might become significant during the actual construction stage. This can lead to; for example, over-break due to unfavourable geological conditions. Even more so, an underestimation of the rock mass properties can lead to unplanned stoppages and tunnel rehabilitation. On-the-other-hand, the excavation method itself, in this case, drill and blast, can also cause severe damage to the rock mass. This can result in over-break and reduction of the strength and quality of the remaining rock mass. Both of these attributes pose risks for the tunnel during excavation and after project delivery.

Blast damage encompasses over-break and the Excavation Damage Zone (EDZ). In the latter irreversible changes occur within the remaining rock mass inside this zone, which are physically manifested as blast fractures. In this thesis, a number of methods to determine blast damage have been investigated in two ramp tunnels of the Stockholm bypass. Herein, a comparison between the most common methods for blast damage investigation employed nowadays is performed. This comparison can be used to select the most suitable methods for blast damage investigation in tunnelling, based on the environment and the available resources. In this thesis Ground Penetrating Radar, core logging (for fractures) and P-wave velocity measurements were applied to determine the extent of the blast damage.

Furthermore, the study of the two tunnels in the Stockholm bypass shows a significant overestimation of the actual rock mass quality during the site investigation. In order to gain a more accurate picture of the rock mass quality, Measurement While Drilling (MWD) technology was applied. The technology was investigated for rock mass quality prediction, quantifying the extent of blast damage, as well as to investigate the potential to forecast the required rock support. MWD data was collected from both grout and blast holes. These data sets were used to determine rock quality indices e.g. Fracture Indication and Hardness Indicator calculated by the MWD parameters. The Fracture Index was then compared with the installed rock support at the measurement location.

Lastly, the extent of the damage is investigated by evaluating if the MWD parameters could forecast the extent of the EDZ. The study clearly shows the capability of MWD data to predict the rock mass characteristics, e.g. fractures and other zones of weakness. This study demonstrated that there is a correlation between the Fracture Index (MWD) and the Q-value, a parameter widely used to determine the required rock support. The study also shows a correlation between the extent of the blast damage zone, MWD data, design and excavation parameters (for example tunnel cross section and charge concentration).

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2018.
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Keywords [en]
Blast damage, Excavation Damage Zone, EDZ, Measurement While Drilling, MWD, Rock support, Rock mass characterisation, Tunnelling
National Category
Geotechnical Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-71402ISBN: 978-91-7790-252-2 (print)ISBN: 978-91-7790-253-9 (electronic)OAI: oai:DiVA.org:ltu-71402DiVA, id: diva2:1259978
Presentation
2019-01-15, F1031, F-huset, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2018-11-01 Created: 2018-10-31 Last updated: 2019-01-07Bibliographically approved
List of papers
1. Measurement While Drilling to Predict Rock Mass Quality and Support
Open this publication in new window or tab >>Measurement While Drilling to Predict Rock Mass Quality and Support
(English)Manuscript (preprint) (Other academic)
Abstract [en]

A tunnelling project is normally initiated with a site investigation to determine the in-situ rock mass conditions and to generate the basis for the tunnel design and rock support. However, since site investigations often are based on limited information (surface mapping, geophysical profiles, few bore-holes, etc.), the estimation of the rock mass conditions may contain inaccuracies, resulting in underestimating the required rock support. The study hypothesised that these inaccuracies could be reduced by using Measurement While Drilling (MWD) technology to assist in the decision-making process. A case study of two tunnels in the Stockholm bypass found the rock mass quality was severely overestimated by the site investigation; more than 45% of the investigated sections had a lower rock mass quality than expected. MWD data were recorded in 25m grout holes and 6m blast holes. The MWD data were normalised so that the long grout holes with larger hole diameters and the shorter blast holes with smaller hole diameters gave similar results. With normalised MWD data, it was possible to mimic the tunnel contour mapping; results showed good correlation with mapped Q-value and installed rock support. MWD technology can improve the accuracy of forecasting the rock mass ahead of the face. It can bridge the information gap between the early, somewhat uncertain geotechnical site investigation and the geological mapping done after excavation to optimise rock support.

Keywords
Measurement While Drilling (MWD), Rock-mass investigation, Tunnelling, Rock mass quality, Rock support, Drill and Blast technology
National Category
Geotechnical Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-71401 (URN)
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2018-10-31
2. Measurement While Drilling (MWD) technology for blasting damage calculation
Open this publication in new window or tab >>Measurement While Drilling (MWD) technology for blasting damage calculation
2018 (English)In: 12th International Symposium on Rock Fragmentation by Blasting, Luleå Sweden 11-13 June 2018 / [ed] Håkan Schunnesson, Daniel Johansson, 2018Conference paper, Published paper (Refereed)
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:ltu:diva-71295 (URN)
Conference
12th International Symposium on Rock Fragmentation by Blasting, FragBlast12
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2019-09-06
3. The History and Future of Rock Mass Characterisation by Drilling in Drifting: From sledgehammer to PC-tablet
Open this publication in new window or tab >>The History and Future of Rock Mass Characterisation by Drilling in Drifting: From sledgehammer to PC-tablet
2017 (English)In: Mine Planning and Equipment Selection (MPES 2017): Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection Luleå, Sweden, August 29-31, 2017 / [ed] Behzad Ghodrati, Uday Kumar, Håkan Schunnesson, Luleå: Luleå tekniska universitet, 2017, p. 99-106Conference paper, Published paper (Refereed)
Abstract [en]

In underground construction projects problematic rock mass conditions are one of the major issues causing cost overruns during the excavation phase. Before a tunneling project starts the rock mass is roughly characterized by a pre-investigation. However, in many cases, these pre-investigation does not portray the rock mass characteristics accurately and do not predict local anomalies in the subsurface. Therefore there is a need for new rock mass characterization methods that can reduce uncertainties and improve the overall tunneling process.

In the end of the 1880s, rock mass characterization based on manual drill data was investigated and rock masses were quantified using drillability. Since then, the technology has significantly changed with the introduction of hydraulic rock drills, computerized drill rigs, and advanced rock mass classification systems based on drill parameters. Nowadays, automatic drill logging systems and drilling data processing software packages are widely available and commonly used in Scandinavian tunneling projects.

This technology uses drilling parameters to characterize the rock mass. However, monitored drill parameters are influenced not only by the variations in the properties of the penetrated rock mass but also by the operator and the rig control system that continuously control the applied forces to optimize drilling and prevent jamming. In order to be useful for geomechanical purposes, the drilling data needs to be filtered, normalized and analyzed to refine the rock related response from responses caused by other influencing factors. If successful the data might be used to determine hardness, fracturing and water indicators.

Even though the technology has shown high potential in laboratory tests and field trials, it is not an obvious choice for all tunneling projects. In this paper, the background of the technology are described and the potential for the future outlined, concluding that the technique probably will be used more extensively in the future. 

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017
Keywords
Measurement While Drilling, MWD, drilling, rock mass characterization
National Category
Other Mechanical Engineering Mineral and Mine Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-68734 (URN)978-91-7583-935-6 (ISBN)978-91-7583-936-3 (ISBN)
Conference
26th International Symposium on Mine Planning and Equipment Selection, Luleå, Sweden, August 29-31, 2017
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-10-31Bibliographically approved
4. Evaluation of Alternative Techniques for Excavation Damage Characterization
Open this publication in new window or tab >>Evaluation of Alternative Techniques for Excavation Damage Characterization
2016 (English)In: ITA-AITES World Tunnel Congress 2016, WTC 2016 / [ed] Society for Mining, Metallurgy & Exploration (SME), United States of America, 2016, Vol. 2, p. 1168-1177Conference paper, Published paper (Refereed)
Abstract [en]

Numerous aspects of underground construction, from structural stability to construction costs, depended on the tunnel quality, including blast damage and the Excavation Damage Zone. Accurately quantifying the extent and severity of damaged rock is a problem. Recent technical developments in the field of Measurement While Drilling (MWD), including software for on-board logging and on-site analysis, have shown potential for rock-mass characterization. Ground Penetrating Radar (GPR) and P-wave velocity measurement have also improved and show similar potential. This paper explores the use of MWD, GPR and P-wave velocity measurements and uses them in techniques for excavation damage characterization and prediction. The paper is based on data collected from a small underground wastecollection site in central Stockholm, Sweden. The data is correlated against rock-mass characteristics and their responses are evaluated. Results indicate potential for excavation damage characterization for all tested techniques, which could minimize blasting damage and improve the over-all tunnel quality.

Place, publisher, year, edition, pages
United States of America: , 2016
Keywords
Excavation Damage Zone, Measurement While Drilling, EDZ, MWD, Drill & Blast, Tunnelling
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-60017 (URN)
Conference
ITA-AITES World Tunnel Congress 2016, San Francisco, 22-28 April 2016
Funder
Rock Engineering Research Foundation (BeFo)
Available from: 2016-10-28 Created: 2016-10-28 Last updated: 2018-10-31Bibliographically approved
5. Measuring of Over-Break and the Excavation Damage Zone in Conventional Tunneling
Open this publication in new window or tab >>Measuring of Over-Break and the Excavation Damage Zone in Conventional Tunneling
2017 (English)In: Proceedings of the World Tunnel Congress 2017: Surface challenges – Underground solutions, 2017Conference paper, Published paper (Refereed)
Abstract [en]

During tunnel excavation, blast induced damage or Excavation Damage Zone(EDZ) interacts with existing geological structure of the rock-mass. This can and cause over-breakand stability issues during and after excavation. Today the EDZ is determined by correlation-basedmethods, although direct measurement is possible. This paper presents investigation methods forEDZ quantification during excavation. The discussed methods are applied in the Stockholm By-Passproject. The literature review and the case study applications are summarized in a comprehensivetable with benefits and limitations of the different investigation methods. The methods discussed canbe used to achieve a better quality of the tunnel contour, especially the direct investigationtechniques. The EDZ can be reduced by adjusting the blasting plan, specific charge as well asimproving the quality of the drill and blasting procedures.

National Category
Construction Management Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-64597 (URN)
Conference
ITA-AITES World Tunnel Congress, Bergen, 9-15 June 2017
Projects
Blasting damage, Drill an Blast, Excavation Damage
Available from: 2017-06-28 Created: 2017-06-28 Last updated: 2018-10-31Bibliographically approved

Open Access in DiVA

fulltext(22797 kB)751 downloads
File information
File name FULLTEXT01.pdfFile size 22797 kBChecksum SHA-512
773cf143db1d82cf1d8eab7be1cf47ab13d5178772f78724b4e3b11761828341841b24a5dd5d1a157434c53bffc678720e65755ce61af52890b63b6a300565c4
Type fulltextMimetype application/pdf

Authority records BETA

van Eldert, Jeroen

Search in DiVA

By author/editor
van Eldert, Jeroen
By organisation
Mining and Geotechnical Engineering
Geotechnical EngineeringOther Civil Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 751 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 543 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf