11.8.3 Locks with indirect filling and emptyingIndirect filling and emptying of low- and medium-head locks is usually
carried out through short culverts in the lateral walls (Fig. 11.9(b)) or
through culverts under the gate sill (Fig. 11.9(c)); for high-head locks
(H12 m) or minor dimensions in plan (B12 m) it is best achieved by
means of long culverts, situated either in the lateral walls (Figs 11.8(c),
11.9(d) and 11.9(e)) or in the bottom (Figs 11.8(d) and 11.9(f )). At the
upstream and downstream ends of the lock, the culverts are provided with
gates (sluice or segment), which must be situated below the lowest pos-
sible water level. To reduce outlet losses the overall cross-sectional area of
all outlet ports should be 1.3–1.5 times as large as the cross-sectional area
of the fully opened culvert gate.
The outlet ports are distributed to ensure, as far as possible, equal
outflow along the culvert length, and are usually staggered and positioned
and shaped to ensure that the outflow into the lock is directed below the
bottom of the vessels in order not to exert lateral forces on them. For the
same reason, the outlet ports of long culverts situated in the lock bottom
are directed towards its walls (Fig. 11.8(d)). The permissible rate of
LOCKS 481
Fig. 11.12 Direct filling of high head locks (after Cˇábelka, 1976)