Question

While designing a hydraulic structure, the piezometric head at bottom of the floor is computed as 10 m. The datum is 3 m below floor bottom. The assumed standing water depth above the floor is 2 m. The specific gravity of the floor material is 2.5. The floor thickness should be

• A. 2.00 m
• B. 3.33 m
• C. 4.40 m
• D. 6.00 m

Answer 1

The correct option is A 2.00 m

Piezometric head at the bottom of floor = 10 m



Pressure head + Datum head = 10

Pressure head + 3 = 10

Pressure head = 7 m

Weight of floor and weight of water above it will counteract this upward pressure head

$2{\gamma }_w+t{G}_s{\gamma }_w=7{\gamma }_w$

$2+2.5t=7\Rightarrow t=2.00m$