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Jianhua Yang - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of rock mass damage evolution during deep buried tunnel excavation by Drill and Blast
Rock Mechanics and Rock Engineering, 2015Co-Authors: Wenbo Lu, Jianhua Yang, Yingguo Hu, Ming ChenAbstract:Presence of an excavation damage zone (EDZ) around a tunnel perimeter is of significant concern with regard to safety, stability, costs and overall performance of the tunnel. For deep-buried tunnel excavation by Drill and Blast, it is generally accepted that a combination of effects of stress redistribution and Blasting is mainly responsible for development of the EDZ. However, few open literatures can be found to use numerical methods to investigate the behavior of rock damage induced by the combined effects, and it is still far from full understanding how, when and to what degree the Blasting affects the behavior of the EDZ during excavation. By implementing a statistical damage evolution law based on stress criterion into the commercial software LS-DYNA through its user-subroutines, this paper presents a 3D numerical simulation of the rock damage evolution of a deep-buried tunnel excavation, with a special emphasis on the combined effects of the stress redistribution of surrounding rock masses and the Blasting-induced damage. Influence of repeated Blast loadings on the damage extension for practical millisecond delay Blasting is investigated in the present analysis. Accompanying explosive detonation and secession of rock fragments from their initial locations, in situ stress in the immediate vicinity of the excavation face is suddenly released. The transient characteristics of the in situ stress release and induced dynamic responses in the surrounding rock masses are also highlighted. From the simulation results, some instructive conclusions are drawn with respect to the rock damage mechanism and evolution during deep-buried tunnel excavation by Drill and Blast.
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dynamic response of rock mass induced by the transient release of in situ stress
International Journal of Rock Mechanics and Mining Sciences, 2012Co-Authors: Wenbo Lu, Ming Chen, Jianhua Yang, Chuangbing ZhouAbstract:Abstract During the excavation of rock mass with the method of Drill and Blast, the release of in-situ stress, also known as excavation load on boundary, is traditionally assumed as a quasi-static process, so the inertia and all other dynamic responses induced by the release of in-situ stress can be ignored. After analyzing the process of release of in-situ stress induced by rock mass excavation with the method of Drill and Blast and determining the duration of the release of in-situ stress, it is found that the release of in-situ stress induced strain rate can reach a magnitude of 10 −1 –10 1 /s or higher if the initial in-situ stress has a level of 20–50 MPa, it implies that the release of in-situ stress is a transient process, and the transient character of the release of in-situ stress and correspondingly induced dynamic response of surrounding rock should be taken into account together with excavation. Problems such as the determination of redistributed in-situ stress corresponding to initiation sequences of millisecond delays, the way and path of the transient release of in-situ stress, transient release of in-situ stress induced vibration and comparison with Blasting induced vibration are also discussed in this paper. Finally, a case of in-situ stress release induced vibration in Pubugou hydropower projects are presented as verifications.
Ming Chen - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of rock mass damage evolution during deep buried tunnel excavation by Drill and Blast
Rock Mechanics and Rock Engineering, 2015Co-Authors: Wenbo Lu, Jianhua Yang, Yingguo Hu, Ming ChenAbstract:Presence of an excavation damage zone (EDZ) around a tunnel perimeter is of significant concern with regard to safety, stability, costs and overall performance of the tunnel. For deep-buried tunnel excavation by Drill and Blast, it is generally accepted that a combination of effects of stress redistribution and Blasting is mainly responsible for development of the EDZ. However, few open literatures can be found to use numerical methods to investigate the behavior of rock damage induced by the combined effects, and it is still far from full understanding how, when and to what degree the Blasting affects the behavior of the EDZ during excavation. By implementing a statistical damage evolution law based on stress criterion into the commercial software LS-DYNA through its user-subroutines, this paper presents a 3D numerical simulation of the rock damage evolution of a deep-buried tunnel excavation, with a special emphasis on the combined effects of the stress redistribution of surrounding rock masses and the Blasting-induced damage. Influence of repeated Blast loadings on the damage extension for practical millisecond delay Blasting is investigated in the present analysis. Accompanying explosive detonation and secession of rock fragments from their initial locations, in situ stress in the immediate vicinity of the excavation face is suddenly released. The transient characteristics of the in situ stress release and induced dynamic responses in the surrounding rock masses are also highlighted. From the simulation results, some instructive conclusions are drawn with respect to the rock damage mechanism and evolution during deep-buried tunnel excavation by Drill and Blast.
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dynamic response of rock mass induced by the transient release of in situ stress
International Journal of Rock Mechanics and Mining Sciences, 2012Co-Authors: Wenbo Lu, Ming Chen, Jianhua Yang, Chuangbing ZhouAbstract:Abstract During the excavation of rock mass with the method of Drill and Blast, the release of in-situ stress, also known as excavation load on boundary, is traditionally assumed as a quasi-static process, so the inertia and all other dynamic responses induced by the release of in-situ stress can be ignored. After analyzing the process of release of in-situ stress induced by rock mass excavation with the method of Drill and Blast and determining the duration of the release of in-situ stress, it is found that the release of in-situ stress induced strain rate can reach a magnitude of 10 −1 –10 1 /s or higher if the initial in-situ stress has a level of 20–50 MPa, it implies that the release of in-situ stress is a transient process, and the transient character of the release of in-situ stress and correspondingly induced dynamic response of surrounding rock should be taken into account together with excavation. Problems such as the determination of redistributed in-situ stress corresponding to initiation sequences of millisecond delays, the way and path of the transient release of in-situ stress, transient release of in-situ stress induced vibration and comparison with Blasting induced vibration are also discussed in this paper. Finally, a case of in-situ stress release induced vibration in Pubugou hydropower projects are presented as verifications.
Reinhold Gerstner - One of the best experts on this subject based on the ideXlab platform.
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Kopswerk II headrace tunnel – construction of the pressure tunnel and associated works / Triebwasserstollen Kopswerk II – Bauarbeiten Druckstollen und Nebenanlagen
Geomechanik Und Tunnelbau, 2011Co-Authors: Herbert Schnetzer, Reinhold GerstnerAbstract:The article concerns the construction of the Kopswerk II pressure tunnel and associated works. Important details of the construction and construction sequence are described, particularly the logistics of a large site in the high mountains. In addition to a summary of the various Drill and Blast tunnels, the article concentrates on the TBM drive and the Drilling and grouting works in the pressure tunnel. Der Beitrag befasst sich mit den Bauarbeiten fur den Druckstollen des Kopswerkes II und dessen Nebenanlagen. Dabei werden die Eckpfeiler der Bauausfuhrung und des Bauablaufes, insbesondere auch die Logistik einer Baustelle im Hochgebirge beschrieben. Neben einem Abriss uber die verschiedenen Sprengvortriebe wird vor allem uber den TBM-Vortrieb und die Bohr- und Injektionsarbeiten im Druckstollen berichtet.
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kopswerk ii headrace tunnel construction of the pressure tunnel and associated works triebwasserstollen kopswerk ii bauarbeiten druckstollen und nebenanlagen
Geomechanik Und Tunnelbau, 2011Co-Authors: Herbert Schnetzer, Reinhold GerstnerAbstract:The article concerns the construction of the Kopswerk II pressure tunnel and associated works. Important details of the construction and construction sequence are described, particularly the logistics of a large site in the high mountains. In addition to a summary of the various Drill and Blast tunnels, the article concentrates on the TBM drive and the Drilling and grouting works in the pressure tunnel. Der Beitrag befasst sich mit den Bauarbeiten fur den Druckstollen des Kopswerkes II und dessen Nebenanlagen. Dabei werden die Eckpfeiler der Bauausfuhrung und des Bauablaufes, insbesondere auch die Logistik einer Baustelle im Hochgebirge beschrieben. Neben einem Abriss uber die verschiedenen Sprengvortriebe wird vor allem uber den TBM-Vortrieb und die Bohr- und Injektionsarbeiten im Druckstollen berichtet.
Kurosch Thuro - One of the best experts on this subject based on the ideXlab platform.
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prediction and classification of tool wear in Drill and Blast tunnelling
2002Co-Authors: Ralf J. Plinninger, Georg Spaun, Kurosch ThuroAbstract:After introducing basic ideas on tools, rock fragmentation and wear mechanisms this paper presents and discusses options to classify bit wear types and to predict the rate of button bit wear. Results show that model tests, such as the CERCHAR scratch test may only give an idea of the rocks abrasivity but show no distinct correlation between encountered tool wear rates. Based on conventional rock parameters and taking into account the whole range of scale from grain mineral to rock mass, the presented schemes may help to predict tool wear rates and hint at possible problems in excavation and specific requirements for the tools used RESUME: According to Point 6.5.2 of the IAEG bylaws all papers must be preceded by an abstract in both English and French. Please have your English abstract translated and include it here so that non-English speaking readers can determine the scope of your work and its conclusions. According to Point 6.5.2 of the IAEG bylaws all papers must be preceded by an abstract in both English and French. Please have your English abstract translated and include it here so that non-English speaking readers can determine the scope of your work and its conclusions.
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PREDICTING TOOL WEAR IN Drill and Blast
T & T international, 2002Co-Authors: Ralf J. Plinninger, Georg Spaun, Kurosch ThuroAbstract:Unexpected Drill bit wear during Drill and Blast tunnelling can prove surprisingly costly. In this article Dipl. Geol. Ralf J Plinninger, Prof. Dr. Georg Spaun and Dr. Kurosch Thuro present their latest methodology for predicting and classifying tool wear.
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Drillability prediction geological influences in hard rock Drill and Blast tunnelling
International Journal of Earth Sciences, 1997Co-Authors: Kurosch ThuroAbstract:Usually the main subject in preliminary site investigations prior to tunnelling projects is the prediction of tunnel stability. During the past years in conventional Drill and Blast tunnelling, problems have occurred also connected to the accurate prediction of Drillability in hard rock. The Drillability is not only decisive for the wear of tools and equipment but is – along with the Drilling velocity – a standard factor for the progress of excavation works. The estimation of Drillability in predicted rock conditions might bear an extensive risk of costs. Therefore, an improved prediction of Drilling velocity and bit wear would be desireable. The Drillability of a rock mass is determined by various geological and mechanical parameters. In this report some major correlations of specific rock properties and especially geological factors with measured bit wear and Drilling velocity are shown. Drilling velocity is dependent on a lot of geological parameters: Those principal parameters include jointing of rock mass, orientation of schistosity (rock anisotropy), degree of interlocking of microstructures, porosity and quality of cementation of clastic rock, degree of hydrothermal decomposition and weathering of a rock mass. Drilling bit wear increases with the equivalent quartz content. The equivalent quartz content builds the main property for the content of wear-relevant minerals. For various groups of rock types different connections with the equivalent quartz content could be detected. In sandstone bit wear is also dependent on porosity or the quality of the cementation. Finally, an investigation program is submitted, which helps to improve the estimation of rock Drillability in planning future tunnel projects.
Nick Barton - One of the best experts on this subject based on the ideXlab platform.
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reducing risk in long deep tunnels by using tbm and Drill and Blast methods in the same project the hybrid solution
Journal of rock mechanics and geotechnical engineering, 2012Co-Authors: Nick BartonAbstract:Abstract There are many examples of TBM tunnels through mountains, or in mountainous terrain, which have suffered the ultimate fate of abandonment, due to insufficient pre-investigation. Depth-of-Drilling limitations are inevitable when depths approach or even exceed 1 or 2 km. Uncertainties about the geology, hydro-geology, rock stresses and rock strengths go hand-in-hand with deep or ultra-deep tunnels. Unfortunately, unexpected conditions tend to have a much bigger impact on TBM projects than on Drill-and-Blast projects. There are two obvious reasons. Firstly the circular excavation maximizes the tangential stress, making the relation to rock strength a higher source of potential risk. Secondly, the TBM may have been progressing fast enough to make probe-Drilling seem to be unnecessary. If the stress-to-strength ratio becomes too high, or if faulted rock with high water pressure is unexpectedly encountered, the “unexpected events” may have a remarkable delaying effect on TBM. A simple equation explains this phenomenon, via the adverse local Q-value that links directly to utilization. One may witness dramatic reductions in utilization, meaning ultra-steep deceleration-of-the-TBM gradients in a log-log plot of advance rate versus time. Some delays can be avoided or reduced with new TBM designs, where belief in the need for probe-Drilling and sometimes also pre-injection, have been fully appreciated. Drill-and-Blast tunneling, inevitably involving numerous “probe-holes” prior to each advance, should be used instead, if investigations have been too limited. TBM should be used where there is lower cover and where more is known about the rock and structural conditions. The advantages of the superior speed of TBM may then be fully realized. Choosing TBM because a tunnel is very long increases risk due to the law of deceleration with increased length, especially if there is limited pre-investigation because of tunnel depth.
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TBM or Drill and Blast : Focus on TBM or Drill & Blast
T & T international, 2003Co-Authors: Nick BartonAbstract:The choice between TBM and Drill and Blast can be quantified, and it may be optimal to choose a hybrid solution for long tunnels through variable rock says Dr Nick Barton of Nick Barton & Associates. Here TBM and Drill and Blast speeds are compared through the Q-value and the Q tbm value, and the strong points of each emphasised
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tbm or Drill and Blast focus on tbm or Drill Blast
T & T international, 2003Co-Authors: Nick BartonAbstract:The choice between TBM and Drill and Blast can be quantified, and it may be optimal to choose a hybrid solution for long tunnels through variable rock says Dr Nick Barton of Nick Barton & Associates. Here TBM and Drill and Blast speeds are compared through the Q-value and the Q tbm value, and the strong points of each emphasised
