Question

A 4.5m4.5m foundation carries a load of 3000 kN. The foundation rests at a depth of 1.5m
below the ground surface. The bearing soil is an extended sand with a saturated unit weight
(γsat) of 19 kN/m3
, modulus of elasticity (E) of 35 MPa, and Poisson’s ratio (µ) of 0.3. The
water level coincides with the ground surface.
a) Determine the effective vertical stresses (σ̍v) for points underneath the corner and
center of the foundation and located at a depth of 6.0 m from the ground surface.
Note: for estimating Δσ̍v (i.e., the additional vertical stresses), use both of the
influence coefficient and approximate methods. Comment on your results.
b) If we consider this foundation as a rigid element, what would be its uniform
settlement under the given load? Is it safe (and why)?
c) Calculate the time-dependent maximum, minimum, and differential settlements of the
foundation if sand is interrupted by a 2m-thick clay layer that starts at a depth of 5m
below the ground surface. Is it safe (and why)?
Note: For the clay, take Cc = 0.2 and e = 0.7.

Answer 1