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A comment on Under Seattle, a Big Object Blocks Bertha. What Is It?. Parent comment

Re:Under Seattle, a Big Object Blocks Bertha. What Is It? by InclinedPlane on Friday December 20, 2013 @03:11AM (#6940504)
The tunnel is not filled with water though. See abduhl's answer for the correct response.
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Re:Under Seattle, a Big Object Blocks Bertha. What Is It? by msandford on Friday December 20, 2013 @12:48PM (#6942768)
The finished tunnel isn't filled with water because it's lined with concrete.

The unfinished tunnel might be filled with water if it wasn't for the pressure that the TBM maintains at the cutting face.

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Re:Under Seattle, a Big Object Blocks Bertha. What Is It? by avn2109 on Friday December 20, 2013 @05:30PM (#6944536)
Not "might." Absent face pressure, the tunnel would definitely be filled with water. This is precisely why they've gone to the trouble of inventing slurry face TBM's and building a recirculating slurry plant on the topside. Hard rock TBM's are much cheaper because they can get away without doing any of that.
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