Rankine active pressure coefficient for a dry, cohesionless…
By Phạm Đức Anh,
Rankine active pressure coefficient for a dry, cohesionless backfill with φ = 30°:
Ka = (1 - sin φ) / (1 + sin φ) = 1/3
Easy to remember, and a good sanity check before trusting any software output for a retaining wall. Coulomb gives a lower value once wall friction is included. #geotechnical #ec7
Replies
James Okoro:
And Kp = 1/Ka = 3 for the same φ, but passive resistance needs much more movement to mobilise, so it is usually reduced or partly ignored in design.
Elena Rossi:
Is at-rest pressure the better choice for a basement wall that cannot move?
Phạm Đức Anh (reply):
Yes. For a propped or stiff basement wall, K0 = 1 - sin φ' (about 0.5 for φ' = 30°) is the usual starting point.