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I'll try to merge some information here. Subsoil: The tunnel is bored in medium densely to densely bedded sand and gravel from the Tertiary and Quaternary. The layers near to the surface are sandy clay and silt. Tunnel coverage: The tunnel roof is about 60 ft beneath the surface. The two exceptions are at the ends were the tunnel comes back to the surface. The minimum coverage of the TBM tunneling is approximately 15 ft. One of these locations is the crossing of the existing rail line. To go through with a TBM the soil gets frozen around the tunnel section to between -1°F and -27°F made possible by a high ground water level. <div>Here is a longitudinal section: <a href="http://www.tunnel-online.info/imgs/100848247_a568acf19c.jpg">http://www.tunnel-online.info/imgs/100848247_a568acf19c.jpg</a></div> <div> TBM: Here is an explanation of the used Mixshield TBM on the manufacturer's (Herrenknecht) website: <a href="https://www.herrenknecht.com/en/products/core-products/tunnelling/mixshield.html">https://www.herrenknecht.com/en/products/core-products/tunnelling/mixshield.html</a> Included on the site is exploded view with detail explanations: <a href="https://www.herrenknecht.com/uploads/pics/130228_TPG_Schnittgrafik_Mixshild_S-623_960_01.1365178380.jpg">https://www.herrenknecht.com/uploads/pics/130228_TPG_Schnittgrafik_Mixshild_S-623_960_01.1365178380.jpg</a> The TBM for the Rastatt tunnel is watertight up to 15 bar.</div> <div> </div> <div>Official broschure: <a>https://www.karlsruhe-basel.de/files/page/02_aktuelles/06_downloads/02_tunnel_rastatt/Bahn_Rohbau_Tunnel_Rastatt_19_8_16-web.pdf</a></div> <div> </div> <div>Aerial view: It is the same as in the previous post. <a href="https://abload.de/img/zwischenablage03eksn3.jpg">https://abload.de/img/zwischenablage03eksn3.jpg</a> (source Drehscheibe Online Forum) There are 56 m (183') left to the end shaft. "Schaden" means damage. The additions are based on the offical DB progress report. Owners design: On the other side of the rail line is another shaft. That was the original end of the TBM tunneling. Between the two shafts a different method using sprayed concrete within frozen soil was suggestion by the owner. That was changed by the contractor with the agreement of the owner to TBM tunneling to the second shaft. At the first glance sprayed concrete against frozen soil seems to be impossible but on the other hand there are lots of tunnels all over Europe that have been built that way. Fahrlachtunnel Mannheim, Germany: <a href="http://www.daub-ita.de/fileadmin/images/daub/TunnelDB/UBD1995134-02.jpg">http://www.daub-ita.de/fileadmin/images/daub/TunnelDB/UBD1995134-02.jpg</a> Frostkoerper = Frozen soil; Spritzbetonschale = Sprayer concrete shell; Bauzustand: Intermediate state; Endzustand: Final state; At first the thickness is determined according to structural requirements. Than 2'' are added which act as insulation and are neglected in calculations. At last is checked if the hydration heat is high enough to ensure hydration/curing of the concrete. A Portland cement is chosen as it delivers the highest hydration heat of all cement types. Additionally an accelerator is added. Here is a link to a German tunnel project in Berlin written in English: dc.engconfintl.org/cgi/viewcontent.cgi?article=1008&context=shotcrete Regards, Volker </div>
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