wrote:
On Wed, 16 Apr 2014 14:37:55 +0100
David Walters wrote:
On Wed, 16 Apr 2014 13:45:26 +0100, Roland Perry wrote:
In message , at 13:31:24 on
Wed, 16 Apr 2014, Paul Corfield remarked:
It is dealing with the damaged tunnel lining between Baker St and Bond
St. The tunnel rings are being slowly replaced in a series of
engineering possessions.

Any information on what caused the damage?

http://www.nce.co.uk/news/geotechnic...line-tunnel-re
air-effort/8648457.article
says
"The primary cause of the damage was clay shrinkage in the
ground around the tunnel, LU principal tunnel engineer Keith
Bowers told NCE. Other factors, including probable issues with
the quality of design and construction, are thought to have
worsened the problem."

More than likely its 99% the latter given that other lines sitting in the
same clay haven't had problems with their tunnels rings in 100 years.

If you'd actually read the article you'd know it's not quite so simple:

“The alignment of the southbound tunnel was driven by the need to pass
under the Bakerloo Line and as result this section of tunnel on the Jubilee
Line is one of the deepest in zone 1, reaching depths of up to 36m,” said
Bowers.

“This depth takes the tunnel out of the London Clay and into the Lambeth
Group, which is highly variable with sand beds within the clay. It is also
faulted.”

According to Bowers, the same design has been used elsewhere on the Tube
network but both tunnels – one in an overrun tunnel at Charing Cross and
another at Heathrow airport – are in London Clay and at shallower depths.

“It is the lining design in combination with the depth and construction
issues that have contributed to the problems on the Jubilee section,” he
said.