Engineering Wonders of the World
Volume I
Forfatter: Archibald Williams
År: 1945
Serie: Engineering Wonders of the World
Forlag: Thomas Nelson and Sons
Sted: London, Edinburgh, Dublin and New York
Sider: 456
UDK: 600 eng - gl.
Volume I with 520 Illustrations, Maps and Diagrams
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54
ENGINEERING WONDERS OF THE WORLD.
SINKING A SHAFT CAISSON.
develop cracks if any settlement of the ground
took place.
The faces of the tunnel where they join the
open approaches are built of polished red
granite of ornamental design, while the other
ends of the cut-and-cover sections terminate in
Nos. 1 and 4 shafts.
There are four circular vertical shafts, two
on each side of the river. These furnish the
completed tunnel with light and ventilation,
and in two cases with means
Shafts. of access from the streets.
They were also used for work-
ing purposes while the tunnel was under
construction.
All the shafts are of the same design, and
were sunk bodily into the ground in the form
of “caissons.” The caissons are huge steel
cylinders, built up of steel
plating, 60 feet in diameter, The
and in one case 100 feet high. ~ .
® Caissons.
Inside each outer cylinder is
an inner one 50 feet in diameter, and the
space, 5 feet in width, between the cylindrical
skins is filled with concrete. At the bottom
the inner cylinder tapers out to meet the
outer, and the two were riveted together to
form a “ cutting edge.” Both skins vary in
thickness from j inch at the bottom to j inch
at the top. Each caisson is provided with