Authors : Abhijeet Vijay Gawai

Volume/Issue : Volume 10 - 2025, Issue 12 - December

Google Scholar : https://tinyurl.com/2bww84kn

Scribd : https://tinyurl.com/yt28hrp3

DOI : https://doi.org/10.38124/ijisrt/25dec486

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Abstract : Tunnel linings constructed using the New Austrian Tunnelling Method (NATM) rely heavily on gantry-mounted formwork systems to achieve accurate geometry, safe access, and efficient concrete placement in highly variable ground conditions. Unlike mechanized methods such as TBM, NATM involves sequential excavation, evolving ground profiles, and continuous adjustments to temporary support-factors that make gantry behaviour far more sensitive to alignment, stability, and operational errors. This paper examines advanced aspects of NATM tunnel gantry operation, focusing on concrete workability, vibration effects, offset control, sway behaviour, curve negotiation, gantry length considerations, and the growing integration of automated systems such as shotcrete robots and expandable gantries. A detailed evaluation of construction-stage failures-including bulk-end blowouts, crown cavities, honeycombing, turnbuckle plate deformation, panel discontinuity, inadequate skin and runner plate stiffness, welding defects, kicker beam cracking, and improper kinematic performance-is presented along with their structural implications. The paper further highlights critical interface- related challenges such as waterproofing lapses, water-load effects, convergence zones, cross-junction transitions, clearance and tolerance management, mock-up validation, and the importance of proper debonding practices. Based on these observations, a set of practical precautions and engineering recommendations is proposed to ensure safer, more reliable, and higher-quality lining construction in NATM tunnels using gantries.

Keywords : NATM Tunnel Lining; Tunnel Gantry Formwork; Concrete Workability; Crown Cavity; Honeycombing; Bulkhead Failure; Turnbuckle Prying Effect; Sway and Stability; Gantry Alignment; Plate Stiffness; Plate Deformation; Welding Defects; Kicker Beam Cracking; Kinematic Checks; Waterproofing Integrity; Water Load Effects; Construction Tolerances; Convergence Zones; Cross-Junction Detailing; Mock-Up Validation; Debonding Practices.

References :

• Books & Technical Publications

1. Arora, N. L. (1977). Transportation Engineering.
2. Saxena, Subash C. (2012). Tunnel Engineering.
3. Jha, Kumar Neeraj. Formwork for Concrete Structures.
4. Bickel, J. O., Kuesel, T., & King, E. Tunnel Engineering Handbook.
5. Austrian Society for Geomechanics Division (ASG). Tunneling – NATM: The Austrian Practice for Conventional Tunneling.
6. ITA Working Group on Conventional Tunneling (2009). General Report on Conventional Tunneling Method.
7. Gawai, A. V., Gowd, N. J. C., & Abhyankar, V. G. (2024). Tunnel Gantries: Fostering Safe, Efficient & Rapid Tunnel Construction.

• Standards, Codes & Guidelines

Indian Roads Congress (IRC) & BIS Codes:

8. IRC:SP 91 — Guidelines for Road Tunnel.
9. IS 4410 (Part 20) — Glossary of Terms Relating to River Valley Projects.
10. IS 4880 (Part 1–7) — Code of Practice for Design of Tunnels Conveying Water.
11. IS 4756 — Safety Code for Tunneling Work.
12. IS 5878 (Part 1–7) — Code of Practice for Construction of Tunnels Conveying Water.
13. IS 15026 (Part 1–2) — Tunneling in Rock Masses – Guidelines.
14. IRC:SP 84 — Manual of Specifications and Standards for Four-Laning of Highways.
15. IS 800 — General Construction in Steel – Code of Practice. IS 816:1969 — Code of Practice for Use of Metal Arc Welding for General Construction in Mild Steel.
16. IS 814 (Part 1 & Part 2):2004 — Covered Electrodes for Manual Metal Arc Welding of Carbon and Carbon Manganese Steel — Specification.
17. IS 2062:2011 — Hot Rolled Medium and High Tensile Structural Steel — Specification.
18. IS 822:1970 — Code of Practice for Inspection of Welds.
19. IS 3658:1999 — Code of Practice for Liquid Penetrant Testing.
20. IS 12666:1989 — Code of Practice for Ultrasonic Testing of Welds.
21. IS 7310 (Part 1):1974 — Approval Tests for Welders Working to Approved Welding Procedures.
22. IS 817 (Part 1 & 2):1992 — Training of Welders — Code of Practice.
23. IS 14687 (Falsework for Concrete Structures) for general practices, design, and safety
24. IRC 087: Guidelines for Formwork, Falsework and Temporary Structures for Road Bridges