Question

The component of which force is to be counterbalanced so that the soil grains remain stable?

(a) Upthrust Pressure Forces

(b) Forces due to Velocity Components

(c) Pressure Force

(d) Seepage Water Force

The question was asked by my college director while I was bunking the class.

Asked question is from Seepage Theories in portion Seepage Theories and Weirs and Barrages Design of Irrigation Engineering

Answer 1

Right choice is (d) Seepage Water Force

For explanation I would say: The seepage water exerts a force tangential to the streamlines at each point in the direction of the flow. This force, when resolved has an upward component from point 5, where the streamline turns upward. So, therefore in order to keep the soil grains stable the upward component of this force should be counterbalanced by the submerged weight of the soil grain.