Week 19 Tunnelling & TBM Course: Segmental Lining Design (Part 2)

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Week 19 (26th May to 29th May) covered the details about the Segmental Lining design. This is the third week of classes on Segmental lining and related issues (previous posts: Week 18 and Week 16).  Mr. Michele Mangione from Arup, UK took us through the Design Methodologies and case studies on Segmental opening support systems.

Mr. Michele Mangione's Lecture on Segmental Lining Design

The general approach of segmental lining design could be briefly summarized as:

1. Determine the level of loading

2. Design Model 

• Analytical Model (Continuum model - Muir Wood / Curtis or Bedded beam model - Duddeck and Erdmann) 
• FEM analysis

3. Compute Normal forces, Shear Forces, Bending Moment and Deflection

4. Design for above member forces

5. Additional design and checks for following conditions: 

• Thrust jacking loads 
• Secondary grouting loads, 
• Storage and lifting loads 
• Birds-mouthing of radial joints 

Flowchart for Tunnel Lining Design

One of the problems often faced by young Tunnel designers is the lack of a single reference (a Textbook/ Guideline) for all design approaches required during segmental lining design. I have made an attempt to review the following guidelines/recommendations and summarize the concepts covered in each reference.

• DAUB recommendations [5] summarizes the design principles very briefly (including fire loads and steel fibers) and serves to be a handy reference. It does not include any example design calculations.

• ITA-WG No. 2's guidelines on Tunnel lining design [6] is another very useful reference for Tunnel designers. The guideline presents the basic concepts yet in detailed way with examples and references. However, it does not cover the concepts like Fire loads and steel fiber segmental linings. 

• British Tunneling Society's Tunnel lining design guide [12] is a comprehensive document for general design philosophy of tunnels. Chapter 5 and 6 summarize the design aspects related to Segmental Lining design. The guideline does not include the details of structural design and does not have examples but has a detailed list of references for further study. The guideline however presents a case history on Channel Tunnel and Great Belt Lining design. 

• Singapore, Land Transport Authority - Guideline for Tunnel Lining Design (Part 1) [9] covers the design guidelines for Segmental Lining. This brief document clearly summarizes the loads, load combinations, typical K values for different soils and numerical models to be considered for the lining design. It also includes a detailed set of example design.

• AFTES (French recommendation) [3] for segmental lining design covers full range of the areas affecting the design and construction of precast concrete segments. This guideline discusses in detail about composition of rings in different types of rings (rectangular, trapezoidal and parallelogrammic segments), contact joints and gaskets. Section 4 of the guideline presents various load combination for design of segments in Serviceable and Ultimate limit states. The unique feature of this guideline is, it presents a table indicating sensitivity/importance of various parameters for different stages of project and for different methods of analysis. 

In a future post, I intend to discuss the different design models and share a spreadsheet to quickly estimate (for pre-dimensioning purposes) the member forces using different design models.

Post class hangout with Mr. Michele Mangione, Arup UK

References:

[1] T. R. Kuesel, E. H. King, and J. O. Bickel, Tunnel Engineering Handbook. London: Springer, 2011, p. 528.

[2] FHWA (US), and Parsons, Technical Manual for Design and Construction of Road Tunnels--civil Elements. AASHTO, 2010.

[3] AFTES, “The design, sizing and construction of precast concrete segments installed at the rear of a tunnel boring machine (TBM),” 2005.

[4] A. M. Wood, Tunnelling: management by design. CRC Press, 2002.

[5] DAUB, “Recommendations for the Design , Production and Installation of Segmental Rings,” pp. 1–56, 2013.

[6] ITA working group on general approaches to the design of tunnels, “Guidelines for the Design of Shield Tunnel Lining,” Tunn. Undergr. Sp. Technol., vol. 15, no. 3, pp. 303–331, 2000.

[7] ITA working group on general approaches to the design of tunnels and F. Report, “Guidelines for the design of tunnels☆,” Tunn. Undergr. Sp. Technol., vol. 3, no. 3, pp. 237–249, 1988.

[8] H. Duddeck, “Future trends in the structural design of tunnels,” Tunn. Undergr. Sp. Technol., vol. 2, no. 2, pp. 137–141, 1987.

[9] J. Poh and G. K. Hun, “Guidelines for Tunnel Lining Design,” Singapore, 2006.

[10] H. Duddeck and J. Erdmann, “Structural design models for tunnels: Tunnelling 82, proceedings of the 3rd international symposium, Brighton, 7--11 June 1982, P83--91. Publ London: IMM, 1982,” Int. J. Rock Mech. Min. Sci. Geomech. Abstr., vol. 20, no. 1, p. A15, 1983.

[11] A. M Wood, “The circular tunnel in elastic ground,” Geotechnique, vol. 25, no. 1, pp. 115–127, 1975.

[12] The British Tunnelling Society, “Tunnel lining design guide,” Thomas Telford, London, 2004.