Question

The following parameters relate to the design of weirs on permeable foundations :

1. Scour depth 2. Exit gradient
3. Uplift pressure 4. Unbalanced head

Design of the downstream end pile of the weir depends upon

• A. 1 and 2
• B. 1 and 4
• C. 2 and 3
• D. 3 and 4

Answer 1

The correct option is C 2 and 3

The downstream vertical cut-off at the end of the pucca floor is used to prevent undermining of foundation. There are two considerations for this purpose :
(i) Uplift pressure
(ii) Safe exit gradient