CONSTRUCTION WITHIN TEMPORARY DAMS.
199
filling tipped in as the wall rises in height. Care must be taken to bring the
wall up in regular lifts as far as possible, contemporaneous, and to avoid any
extensive “ racking back,” which causes inequality of pressure on the founda-
tion, and necessitating abrupt
changes in the timbering, may
induce vertical cracks in the
wall.
Trenching was adopted for a
quay wall at Belfast as indicated
in fig. 132, which also shows the
nature of the strata dealt with.
Sleetch is the local name for
slightly indurated or compact
mud.
Construction within Tem-
porary Dams. —The foregoing
sections have dealt with sites
more or less inland during the
period of construction. Of the
many ways in which the work
may be carried on when the site
is continuously under water, the
following is one which admits
Fig. 131. —Timbered Trench.
DOCK
HÜ1
Scale, 20 feet to 1 incb.
Fig. 132. —Quay Wall at Belfast.
of constructive work, under normal conditions, after the initial provision
of a watertight compartment.