Civil Engineering Reference
In-Depth Information
A major tunnel on this route was the Box Tunnel with a length of
2937 m. Water was a major problem on several sections of this tunnel,
but it opened successfully in 1841.
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1857 saw the start of construction on the first major tunnel in the
Alpine regions of Europe. The Fréjus Tunnel involved construction
between two portals, one at 1344 m above sea level at Bardonnéche
and the other at 1202 m at Fourneaux, with the distance between portals
being 12,221 m. Rock drills were used extensively on the project and
drill carriages mounting four to eight drills were introduced in 1863
and used until the completion of the project in 1870.
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At about the same time as the first Alpine tunnels were being constructed,
the Hoosac Tunnel in Massachussetts, USA was started (1855-76). This
became known as 'the Great Bore'. It was 7.44 km long (4.62 miles)
and was constructed mainly through schist and gneiss. The rate of
construction was very slow at 0.32 m per day in 1865, but this improved
with the introduction of compressed air rock drills to about 1.65 m per
day in 1873.
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1869 was an important year for subaqueous tunnelling as it marked
the successful completion of the Tower subway in London using a shield
(designed by J. H. Greathead) and cast iron lining. The shield used is
the ancestor of almost all subsequent tunnelling shields (it was circular
as compared to Brunel's rectangular shield used on the earlier Thames
Tunnel). It even incorporated grouting behind the cast iron lining to
fill the void. The system was very efficient and allowed progress of
3 m per day. The tunnel was 2.18 m in diameter and 402 m long.
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Greathead made a number of further developments in shield tech-
nology, including a closed face shield with the ground being broken
up with jets and the spoil being removed as a slurry, i.e. the forerunner
of the slurry shield. (A slurry shield was first used in 1971 at New
Cross in London, UK.)
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The first use of hydraulic jacks to propel a shield forward was designed
by Beach in 1869 and used under Broadway in New York, USA.
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There were a number of developments in rotary tunnelling machines
as part of the various attempts at the Channel Tunnel, UK in the 1880s.
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Compressed air was used as a means of preventing water inflow into
the tunnel during the construction of the Hudson river tunnel in New
York, completed in 1910. This project also introduced the 'medical
lock' for treatment of caisson disease. At about the same time the first
(old) Elbtunnel under the Elbe river in Hamburg also used compressed
air during construction between 1907 and 1911. It suffered a blowout
in 1909 with an 8 m high water fountain being observed. It should be
noted that a patent for working in compressed air had been taken out
in 1830 by Lord Cochrane in the UK.
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The first use of a combination of a shield and compressed air (together
with cast iron segmental lining) was on the City and South London
