Rail Traffic Chaos Southern Germany

[beaulieu]

Rail Traffic between Germany and Switzerland has decended into total chaos. The route between Stuttgart and Zürich is closed between Horb and Böblingen for scheduled maintenance, and the route between Zürich and München is closed between St. Margarethen(CH) and Bregenz(AT). Last night following two days of rain a tunnel being bored under the Two Main Track mainline at Rästatt(south of Karlsruhe) closed the Rhein Valley mainline used by more than 200 trains per day. The only electrified detour route available is via Saarbrücken and Strasbourg through France. The only other routes are a couple of lines south from Ulm that are not electrified and both involve some single track segments.

Photo of misfortune is here 

Some sources suggest that the only solution is to fill the tunnel in with concrete and abandon the TBM which is going to take some time. Currently passengers are being bussed between Karlsruhe and Baden-Baden.

[blue streak 1]

IRJ version in English.

 

http://www.railjournal.com/index.php/main-line/rastatt-tunnel-landslip-closes-karlsruhe-basle-main-line.html?channel=524

 

[CMStPnP]

http://itools.com/tool/google-translate-web-page-translator

Blue Streak:  Just Google Website translator and enter the web address in the first post and then enter GERMAN to ENGLISH and you can read the full text of the German article plus the links as well as the reader comments and the link to the German Railfan Forum..........Google will translate all to English for you.    It is really a nice tool as you can follow links and the linked page will translate as well.

[CMStPnP]

Interesting they are tunneling under former swampland of the Rhine River Valley.

[Anonymous]

CMStPnP

Interesting they are tunneling under former swampland of the Rhine River Valley.

I think the designation “swampland” is misleading.

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.

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.  Parts are built in cut and cover method, the rest as open trough. 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.

Here is a longitudinal section:
http://www.tunnel-online.info/imgs/100848247_a568acf19c.jpg

What went wrong is not known yet. There are possible scenarios but they would be speculation. I expect a number of contribution factors.

 

The SWR, a regional TV station, reports that the tunnel will be filled with concrete on a length of 160 ft sacrificing the TBM worth about $40 Mio.Most important for Deutsche Bahn (DB) is to get the damaged main line back into operation.

 

Building subway tunnels in ancient river valleys is quite common. Think of Cologne, Duesseldorf (both River Rhine), Hamburg (River Elbe). In the beginning in Germany with the cut and cover method and after 1955 using TBMs.

 

The fourth tunnel tube crossing the River Elbe was built with a TBM while the first three were built with floated in position and lowered concrete elements.
Regards, Volker

[MidlandMike]

I thought TBMs set a liner continuously behind themslves.

[CMStPnP]

I think "swamp" or "swampland" was a term used in the article.   Though your probably right on it being misleading as reporters do not do much due diligence anymore before their article is published.

[beaulieu]

MidlandMike

I thought TBMs set a liner continuously behind themselves.

 

No there is a gap between the rear of the shield portion of the TBM and the last liner ring that was set. If there wasn't then the liner segments couldn't be installed.

[Anonymous]

Here is an explanation of the used Mixshield TBM on the manufacturer's (Herrenknecht) website: https://www.herrenknecht.com/en/products/core-products/tunnelling/mixshield.html

Included on the site is exploded view with detail explanations: https://www.herrenknecht.com/uploads/pics/130228_TPG_Schnittgrafik_Mixshild_S-623_960_01.1365178380.jpg

The TBM for the Rastatt tunnel is watertight up to 15 bar.
Regards, Volker

[Anonymous]

CMStPnP

I think "swamp" or "swampland" was a term used in the article. Though your probably right on it being misleading as reporters do not do much due diligence anymore before their article is published.

I got my information from the official broschure for the tunnels. It contains a geological description of the subsoil. Sorry, it is only available in German.

https://www.karlsruhe-basel.de/files/page/02_aktuelles/06_downloads/02_tunnel_rastatt/Bahn_Rohbau_Tunnel_Rastatt_19_8_16-web.pdf

And an arial view with tunnel in red and crossing with rail line in the middle of the lower edge: https://www.karlsruhe-basel.de/files/page/04_tunnelbauwerke/01_tunnel_rastatt/01_kurzbeschreibung/Schema_rastatt.jpg
Regards, Volker

[MidlandMike]

beaulieu

 

 

MidlandMike

I thought TBMs set a liner continuously behind themselves.

 

 

 

 

No there is a gap between the rear of the shield portion of the TBM and the last liner ring that was set. If there wasn't then the liner segments couldn't be installed.

 

The diagram link in Volker Landwehr's post shows that the liner rings are added inside the shield, and the annular gap is continuously grouted.  I suspect that failure of the grout along the tunnel liner may have allowed fluid migration and washout.

[Anonymous]

MidlandMike

I suspect that failure of the grout along the tunnel liner may have allowed fluid migration and washout.

That might be a contributing factor. It would lead to high settling. But I think that could be fixed with grout injections. I don't think that it would lead to the abandonment of the TBM ($20 Mio. per TBM) when filling the tunnel segment with concrete.

I think there must have happened something more severe perhaps (speculation) collapse of a tubbing segment.

Here is a reworked aerial view showing the location of the head of the TBM (Kopf TBM): https://abload.de/img/zwischenablage03eksn3.jpg  (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.

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.

This was a first time. But as the TBM has advanced by far from the damage I doubt this was the reason.

With a coverage of just 13' the compression forces in the tubbing segments are not very high. So moments and the connections between the segments get more important.

I think we have to wait for the results of the investigation. It is not sure in Germany that it will be published.
Regards, Volker

[MidlandMike]

A big washout may have resulted in loss of support for the liner which might be a cause of a liner collapse.  Cement curing is an exothermic/heat producing process, so it seems that spraying cement on to frozen ground would be an incompatible combination.

[Anonymous]

MidlandMike

Cement curing is an exothermic/heat producing process,

As a civil engineer in structural design I know that and usually the curing stops below 14°F till it gets warmer again.

MidlandMike

so it seems that spraying cement on to frozen ground would be an incompatible combination.

At the first glance that seems to be right but on the other hand there are lots of tunnel all over Europe that have been built that way. Fahrlachtunnel Mannheim, Germany:
http://www.daub-ita.de/fileadmin/images/daub/TunnelDB/UBD1995134-02.jpg

Frostkoerper = Frozen soil; Spritzbetonschale = Sprayer concrete shell; Bauzustand: Intermediate state; Endzustand: Final state;

I have never been in tunneling so I don't know the concrete recipe. The temperatures of the frozen surface are said to be between 23°F and 11°F.

---

Regards, Volker

Edit: I have browsed for information about sprayed concrete on frozen soil. What I found is as follows. At first the thickness is determined according structural requirement. Than are 2'' 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

 

 

[Anonymous]

There is a few new information about what happened. According to different press releases of Deutsche Bahn and media reports tubbing segments were displaced on a length of approximately 130 ft behind the TBM's shield with ingress of soil and water. Sounds like a kind of zipper effect.

The tunnel will be filled with concrete on a length of about 500 ft a total of about 130,000 cubic feet of concrete burying the TBM.

To restore the mainline everything is taken out, a 400 ft long, 50 ft wide, and 3'-4'' thick concrete slab gets poured and the rails replaced.

If they will restore the filled tunnel I don't know.
Regards, Volker