Week 5 (17th Feb '14 to 21st Feb '14) of 2nd Level specializing course in Tunnelling and TBM covered the concepts of Tunnel supports (overview and key design concepts) which included:
- General overview of Supports (Temporary and Permanent)
- Recent developments in support system types (Rock bolting, Shotcrete, Steel sets/ Lattice girder, wire mesh etc)
- Water proofing of Tunnel using Conventional Tunnelling and TBM
- Method 1: Closed form solution - Define the loads (independent of the behaviour of system), Idealize geometry, apply the loads (with partial safety factor) to obtain the results (like Terzhaghi - 1946 method).
- Method 2: Convergence Confinement Method. Partial safety factors on the loads are not applied. Factor of safety are however applied on the final response for the design.
- Method 3: Limit Equilibrium Method
Other Aspects Covered:
- Brief on 2008 Kresten Lecture (more details here)
- Reinforced rock mass - Equivalent Parameters (Spreadsheet to calculate, to be updated)
- Bedded Beam Spring Model
- Use of commercially available software - "RocSupport" to understand convergence confinement (a part of the functionality is reproduced in this spreadsheet here)
- Equivalent model for Steel Set - Shotcrete system
Mr. Peinsitt give us a lecture on the drilling tools and road header used in Tunnelling. Mr. Peinsitt gave us a comprehensive overlook on the applications of road header for excavation of tunnel and explained innovative methods to combine road header excavations with D&B excavation and TBM excavation with practical examples. The lecture was followed by a practical exercise to assess the suitability of a roadheader for a particular problem.
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| Mr. Hanno Bertignoll (Sandvik)'s Lecture on Roadheader and Drilling Tools |
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| Mr. Airoldi (Minova / Atlas Copco)'s Lecture on Rock Anchor and their application |
| Self Drilling Anchors (SDA) made of Fiber glass and Steel |
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| Split Sets |
| Swellex Anchor (Initial and Inflated position) |
| Prototype of Symmetrix Drilling Bit (Assembled and Individual parts) |
References:
[1] E.Hoek et. al, "Support of Underground Excavations in Hard Rock", A.A. Balikema Publishers, The Netherlands
[2] Chapter 5 - Dimitrios Kolymbas, "Tunnelling and Tunnel Mechanics - A Rational Approach to Tunnelling", Springer Publishers
[3] Chapter 11 - Brady, B.H.G. and Brown, E.T. 1985. Rock mechanics for underground mining. London: Allen and Unwin, USA
[4] Chapter 9 - E.Hoek et al, "Underground Excavations in Rock", E & FN Spon Publishers, London
[5] Chapter 12 - B. Singh et. al "Tunnelling in Weak Rocks", 2006, Elsevier Publishers, London
[6] Hoek, Evert, et al. "The 2008 Kersten Lecture Integration of geotechnical and structural design in tunneling." 56th Annual Geotechnical Engineering Conference. 2008 (available here)
[7] Hanna, T.H. (1982). "Foundations in Tension GroundAnchors" Vol. 6 of Series on Rock and Soil Mechanics. Trans Tech and McGraw-Hill, USA
[8] Method of calculating grouted tie rods and micropiles (in French) : Bustamante, M; Doix, B Bull Liaison Lab Ponts ChaussesN140, Nov–Dec 1985, P75–92 (DOI: http://dx.doi.org/10.1016/0148-9062(86)90866-1)
[9] Grasso, P., A. Mahtab, and S. Pelizza. "Reinforcing a rock zone for stabilizing a tunnel in complex formations." Int. Congr. on Progress and Innovation in Tunnelling, Toronto 2 (1989): 663-70.
[10] Galler R., Doucet C., Gschwandtner G.G., "Roofex® bolt and its application in tunnelling by dealing with high stress ground conditions" Workshop "Berechnungsverfahren in der Geotechnik - Versagensmechanismen und Parameterentwicklung", Austrian Society for Geomechanics, Salzburg, Austria
[11] Carranza-Torres, C. and Diederichs, M.S. "Mechanical analysis of a circular liner with particular reference to composite supports –e.g., liners consisting of shotcrete and steel sets", Tunneling and Underground Space Technology, Feb 2009
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