Question

BY increasing the length of the floor on the upstream of the weir axis?

(a) the uplift pressure will increase below the floor downstream of the weir

(b) the uplift pressure will decrease below the floor downstream of the weir

(c) the uplift pressure will remain the same in both cases

(d) the uplift pressure may increase or decrease

I got this question in examination.

I'd like to ask this question from Seepage Theories topic in section Seepage Theories and Weirs and Barrages Design of Irrigation Engineering

Answer 1

Right choice is (b) the uplift pressure will decrease below the floor downstream of the weir

Explanation: The value of upstream cutoffs has a considerable effect on decreasing the uplift pressure especially from a value of 1 m to 2 m. The provision of sheet pile at the U/s end and sufficient thickness of floor resists the uplift pressure.