Question

Two lock gates of `7.5 m` height are provided in a canal of `16 m` width meeting at an angle of `120^@`. Calculate the force acting on each gate when the depth of water in upstream side is `5 m`.

Answer 1

Height of lock gates `=7.5m`
Width of canal `=16m`
Inclination of gates `=120^@` and `H=5m`
From the geometry of the lock gates, we find that inclination of the lock gates with the walls
`a=(180^@-120^@)/2=30^@`
and width of each gate `=(16/2)/(cosalpha)=8/(cos30^@)=8/0.866=9.24m`
Therefore, wetted area of each gate
`A=5xx9.24=46.2m^(2)`
and force acting on each gate is
`F=gAxx(H/2)=9.81xx46.2xx(5/2)=1133kN`