Hydraulic Structures: Fourth Edition

the closure of very high openings); in the case of flow over the top of the
gate it may be provided with an additional flap gate. The gates can have
slide or wheeled support (e.g. Fig. 4.20). In the latter case fixed wheels
(most frequent type), caterpillar or a roller train (Stoney gate) may be
used; for fixed wheels their spacing is reduced near the bottom. The gate
seals are of specially formed rubber (Fig. 6.1).
The gate weight, G, is related to its span, B(m), and the load, P(kN),
by

Gk(PB)n. (6.1)

For slide gates with PB200 kN m, k0.12 and n0.71; for wheeled
gates and PB270 kN m, k0.09 and n0.73. The usual range of heads
for single plain gates is 1H(m)15, and of spans 4B(m)45.
The product of span Band head at the bottom of the gate His
usually kept below 200 m^2 (Smith, 1978); in special cases sliding gates with
larger values have been used (e.g. Scheldt, The Netherlands, 250 m^2 ) (see
also Section 6.4).

CREST GATES 269

W

0.1W

1:12

taper

skin

plate

WATER

PRESSURE

guide rollers

FLOW

side seal

a) b)

Fig. 6.1 Vertical lift gate (Lewin, 2006)