Test: Seepage Analysis - 2 - Civil Engineering (CE) MCQ

Darcy's law is valid if the flow through soil is laminar and Reynolds number is less than 1.

Seepage force is due to frictional drag and its magnitude is given by iγ_w per unit volume of soil. For quick condition during upward flow.
Effective stress = total stress - pore pressure So statement 1 and 3 is correct.

When the seepage of water is upward in a soil layer so much that seepage force decreases the inter particle forces and effective stress is reduced to zero, quick sand condition occurs. Liquefaction of sand is also a phenomenon when effective stress of soil is reduced to zero, it usually occurs when sand deposit is shaken due to an earthquake or any other oscillatory load which increases the pore water pressure.

∴ Maximum permissible exit gradient,