When a consolidation test is performed on some soils, the virgin compression region is not linear, but bilinear. The figure shows such a compression curve from a 15 ft thick layer.

(a) What vertical strain, ε_v, occurs when the soil is loaded from an initial σ’_v1 = 560 psf to σ’_v2 = 3000 psf?

(b) If you load the soil further, to σ’_v3 = 4000 psf, how much additional settlement occurs?

(c) Finally, if you unload from 4000 psf back to σ’_v4 =3000 psf, what additional deformation (in feet) occurs?

o'y = 560 psf = 980 psf Ca = 0.17 Cr. = 0.032 |o2 = 3000 psf Ce = 0.14 o'i3 = 4000 psf log o,