This blog post is with reference to my previous post related to the lecture series on Design and Selection of TBM and it attempts to summarize the Recommendations for TBM Selection practiced in the following countries:
- Germany, Switzerland, Austria (German speaking countries)
- France
- Japan (only soft ground)
- Norway (only hard rock)
- Italy
Following references are cited in this post:
[1] Chapter 19, "Mechanised Shield Tunnelling, 2nd Edition", Maidl. B et al., Ernst and Sohn Publishers, Berlin, 2011. ISBN 978-3-433-02995-4 (link)
[2] ITA working group on Mechanized Tunnelling, "Recommendations and Guidelins for Tunnel Boring Machines (TBMs)", ITA-AITES, 2000 (link)
[3] AFTES Working Group no. 4, "New Recommendtaions on Choosing Mechanized Tunnelling Techniques", Tunnels et Ouvrages Souterrains, Hors-Serie No. 1, 2005
It should be realized that it is not possible to draw up an analytical method for choosing the most suitable TBM. All the above guidelines just give definition/classification of different types of TBM, highlights the scope of application and analyses the effect of selection criteria (geological, project, cost, etc.)
German speaking countries mostly follow, DAUB recommendations [4] for the selection of Tunnelling machines and in my opinion, the DAUB recommendations are very comprehensive (which also includes the technical features of the machines). It also summarizes the Rock/Soil parameters which could be used as a thumb rule for the selection of TBM. Following figures shows the classification of TBMs according to DAUB and the general work flow for finalization of Type of TBM. It can be noticed that DAUB's classification system is based on machine type.
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| Classification of TBMs - DAUB [1] |
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| Flowchart for Selection of TBM |
In addition to the above TBMs, DAUB also defines special types of TBM (Blade schields, Multiple circular shield). Terminology used for different machines are dependent on the country of use and hence it should be considered while comparison.
French Tunnelling Association's recommendations (AFTES) [3] have a classification system based on the support type (shown below). In addition to definition of TBM types and applicability, AFTES recommendations have evaluated the effect of different parameters on different type of Tunnelling techniques and is tabulated on a three point scale. This helps the designer to check all the factors affecting a particular choice of TBM.
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| Classification of TBMs - AFTES [3] |
ITA Working Group No. 14 report on Selection of TBM [2] provides comprehensive guidelines and recommendations in the form of four individual reports representing Japan, Norway, Germany, Austria, Switzerland, France and Italy. The Japanese working group's TBM classification is similar to the one in DAUB. In addition to the applicability matrix of different types of TBM for different soil conditions, it also makes a comparison with the Drill & Blast method and gives a basic flowchart for selection of TBM for soft ground (shown below).
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| Flowchart for Selection of Softground TBM - Japanese WG [2] |
Norway has developed guidelines for TBM selection for Hard Rock wherein the prognosis model decides the type of TBM and the tools required to achieve a balance between economy (tools consumption) and progress rate. The document further explains the procedure to calculate cutting rate, progress rate, cutter consumption etc.
In the Italian Working Group report to ITA, along with basic classification and definition of TBMs, emphasis has been given to indicate the type of geotechnical and geological tests needed at different stages of design to select the most appropriate TBM.
Additional Reference:
[4] Recommendation produced by the working group, "Recommendations for the selection of tunnelling machines", German Tunnelling Committee (DAUB)
[5] “Project Report 1-94, Hard Rock Tunnel Boring”, published by University of Trondheim, The Norwegian University of Science and Technology, NTH Anleggsdrift (link)
[6] Tunnelbohrmaschinen im Hartgestein. Ernst & Sohn, 2001 (link)
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