Talk:Tunnelling shield

Illustrations or it didn’t happen
This and the related articles cry out for some illustrations. Well done illustrations would be far more useful than photographs for it.JimD 20:57, 2004 Jun 21 (UTC)


 * I agree, though at the moment even some photographs would be an enourmous improvement, as there's not much of a physical description of the devices -Lommer 02:05, 22 Jun 2004 (UTC)


 * I concur --Commander Keane 12:00, 1 Apr 2005 (UTC)

Tunnelling/Tunneling
The concurrent use of two variant spellings annoys me. The article is called "tunnelling shield". Could we use tunnelling throughout? Everybody got to be somewhere! (talk) 22:28, 11 March 2010 (UTC)

Diameter
Used for what sizes of bore diameter? --Helium4 (talk) 05:12, 21 July 2016 (UTC)
 * I have added the diameters of some of the early bored tunnels as examples. Paul W (talk) 17:50, 26 July 2016 (UTC)

Waaah! I don't understand how it works!
I'm trying to imagine the process. As boring progresses, I gather that the existing shield is continually being extended into the newly-created space--but it seems like a chicken-and-egg problem; how can any work be done in that newly-created space until it has shielding? Also (although this question is more about boring than about shielding), how does the whole process start and end? A thousand thanks to anyone who expands the article so that it explains these things. Oh, and: The article says that the shield is in place only during the work; how is it later removed? DSatz (talk) 10:52, 21 June 2020 (UTC)
 * There are several ways this happens.
 * The sheld is long enough to give the men working at the face space to work; ~20ft. As the shield is moved forward, there is a gap between the built tunnel wall and the shield. This short distance is small enough that the dirt does not collapse.
 * The shield is in a pressurized segment of the new tunnel. The high air pressure holds the dirt in place.
 * Extremely thin, 1 cm, circular bracers can be inserted as the shield moves forward.
 * Cement can be hydraulically, at high pressure, pumped through the back portion of the shield, to solidify between the shield and the dirt, before the shield is moved forward.
 * Semicircular steel plates can be placed abuting the built tunnel, and touching the inside of the shield. As the shield moves forward the plates stay abuting the built tunnel. When the shield moves out from under them, they are pushed into place, and new plates are started.
 * There are other methods. I am not an expert, and this is from memory, from reading long articles about building various early tunnels.
 * This is just to give an idea of how it is done. Nick Beeson (talk) 12:51, 28 March 2021 (UTC)

History edits
The statements of fact in the history section were out of chronological sequence, and contained redundancies. I put the section into chronological sequence and I removed the redundancies.

I removed these two contradictory statements. Barlow was joint Engineer [with Greathead?] to the project until his death Greathead independently came up with his own designs They cannot both be simultaneously true.

I removed a substantial amount of "original research." Statements of opinion without any reference. In particular I removed this: In any competent history of tunnel design using shields, there ought to be recognition of three men by name for their built designs: Brunel, Beach, and Greathead. Whilst Barlow had an idea, he never actually built either his patented shield design or his later provisional patent design which was never ratified. While this is not a complete history of tunnel shields as more evidence is coming to light each year from digital archives around the world of older publications, the timeline of their development is becoming more coherent and clear than ever before as a result. which is unique in my 15 years of editing (thousands of edits). It is pure opinion about the article, and contains no article-content.

I removed this Whilst many attribute the design shift from rectangular to cylindrical to Barlow, because it contains a canonical weasel word, "many", is a statement of opinion, and apears to be original research. Nick Beeson (talk) 12:31, 28 March 2021 (UTC) I recognise all these removed paragraphs as direct quotations from a 1902/6 publication by Copperthwaite who was once Greathead's pupil. To find out the exact publication I suggest looking at the Greathead page which is very well documented. Ashattock (talk) 21:36, 16 November 2022 (UTC)

"They cannot both be simultaneously true." I disagree. Greathead invented his circular shield design, patented it and used it in the Tower Gateway project as the engineer he was. Whilst Barlow was the chief engineer, Greathead was the engineering contractor. There is, however, a missing comma which introduces confusion in the statement.

"canonical weasel word, "many", is a statement of opinion". canonical weasel word. Lol. Many words were fed to the editor and as many removed by a moderator. Surely it would have been better to twist a few citations instead? Just a thought. "...there ought to be recognition of three men by name for their built designs: Brunel, Beach, and Greathead..." that's a true statement based on factual evidence which, unfortunately, was not cited. Brunel invented rectangular shield design, Greathead invented, patented and built the first ever circular shield, Alfred Beach may have pinched Barlow's design and all three were the first to build timeless tunnels with those original inventions.

I know these things as part of my honours degree civil engineering research Ashattock (talk) 21:52, 16 November 2022 (UTC)