Yestersay (25th March, 2014), we had a special lecture by Prof. Kalman Kovari, as a part of Second Module of Tunnelling and TBM course and also as a part of ITACET Training seminar being organized in Politecnico di Torino. During the lecture Prof. Kalman Kovari gave us case studies of Urban Tunnelling with extreme conditions of constraints / exceptionally different geologic conditions. Based on these case studies, Prof. Kovari explained us the thought process during the conception stage and the design stage.
Prof. Kovari also gave us the fundamentals required to understand the upcoming lecture on face stability calculations for Slurry and EPB type TBM drivel.
[Update: Prof. Anagnostou's lecture followed this lecture to cover the details about face stability. I have shared a spreadsheet for face stability estimation based on his lecture at this location (link)]
In particular, Prof. explained us the design and construction of the Ceneri Base Tunnel cavern (24m wide and 17m height) along with the complex problems in executing and monitoring [1].
We also used this opportunity to clarify some of the concepts explained in his paper on NATM [2]. In my previous blog post (here), there was a discussion about Convergence-Confinement Curve and I had mentioned that the trough-shape response curve (as depicted in all NATM literature) are realistic for shallow tunnels and is due to the material softening. But according to Prof. Kovari, trough-shaped ground response curve is simply not realistic. He emphasized that it does not have any theoretical background and can not be accepted even for shallow tunnels. The trough-shaped response curve could be noticed only in certain special cases (eg. when there is a blocky wedge failure in the tunnel).
References:
[1] Filippini, R., Kovári, K., & Rossi, F. (2013). Ceneri-Basistunnel. In Swiss Tunnel Congress 2013 (pp. 236–249).
Retrieved from: http://www.filippini-ing.ch/documenti/STC_2013-CeneriBasistunnel.pdf
[2] K. Kovári, “Erroneous Concepts behind NATM,” in Rabcewicz-Geomechanical Colloquium, Salzburg, 1993, p. 21. (Available at Swiss Federal Institute of Technology site, here)
Prof. Kovari also gave us the fundamentals required to understand the upcoming lecture on face stability calculations for Slurry and EPB type TBM drivel.
[Update: Prof. Anagnostou's lecture followed this lecture to cover the details about face stability. I have shared a spreadsheet for face stability estimation based on his lecture at this location (link)]
In particular, Prof. explained us the design and construction of the Ceneri Base Tunnel cavern (24m wide and 17m height) along with the complex problems in executing and monitoring [1].
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| Prof. Kalman Kovári's Lecture on Urban Tunnelling |
References:
[1] Filippini, R., Kovári, K., & Rossi, F. (2013). Ceneri-Basistunnel. In Swiss Tunnel Congress 2013 (pp. 236–249).
Retrieved from: http://www.filippini-ing.ch/documenti/STC_2013-CeneriBasistunnel.pdf
[2] K. Kovári, “Erroneous Concepts behind NATM,” in Rabcewicz-Geomechanical Colloquium, Salzburg, 1993, p. 21. (Available at Swiss Federal Institute of Technology site, here)
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