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van Eldert, J., Schunnesson, H., Johansson, D. & Saiang, D. (2019). Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling. Rock Mechanics and Rock Engineering
Open this publication in new window or tab >>Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling
2019 (English)In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453XArticle in journal (Refereed) Epub ahead of print
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 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 25 m grout holes and 6 m 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.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Measurement while drilling (MWD), Rock mass investigation, Tunnelling, Rock mass quality, Rock support, Drill and blast technology
National Category
Mineral and Mine Engineering Infrastructure Engineering Construction Management Geotechnical Engineering Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-76382 (URN)10.1007/s00603-019-01979-2 (DOI)000489294700001 ()
Funder
Rock Engineering Research Foundation (BeFo), 344
Available from: 2019-10-14 Created: 2019-10-14 Last updated: 2019-10-28
van Eldert, J. (2018). Analysis of Excavation Damage, Rock Mass Characterisation and Rock Support Design using Drilling Monitoring. (Licentiate dissertation). Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Analysis of Excavation Damage, Rock Mass Characterisation and Rock Support Design using Drilling Monitoring
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
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:nbn:se:ltu:diva-71402 (URN)978-91-7790-252-2 (ISBN)978-91-7790-253-9 (ISBN)
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
van Eldert, J. (2017). Measuring of Over-Break and the Excavation Damage Zone in Conventional Tunneling. In: Proceedings of the World Tunnel Congress 2017: Surface challenges – Underground solutions. Paper presented at ITA-AITES World Tunnel Congress, Bergen, 9-15 June 2017.
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
van Eldert, J., Ittner, H., Schunnesson, H. & Johansson, D. (2016). Evaluation of Alternative Techniques for Excavation Damage Characterization. In: Society for Mining, Metallurgy & Exploration (SME) (Ed.), ITA-AITES World Tunnel Congress 2016, WTC 2016: . Paper presented at ITA-AITES World Tunnel Congress 2016, San Francisco, 22-28 April 2016 (pp. 1168-1177). United States of America, 2
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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1923-044x

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