Pore pressure, effective stress and drainage - The Mechanics of Soils and Foundations - page 84

ground level:

•

in the clay:

σ = 100 kPa, as in (b)

z

u 20 kPa, as in (a)

σ z = σ z −

=

u = 100 − 20 = 80 kPa

•

in the sand there has been no change of total stress or pore pressure and the
stresses are the same as those in (b).

Reference

Terzaghi, K. (1936) 'The shearing resistance of saturated soil and the angle between the planes of
shear', Proceedings of 1st International SMFEConference , Harvard , Mass ., Vol. 1, pp. 54-56.