When a consolidation test is performed on some soils, the virgin compression region is not...

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

(a) What vertical strain, εu, occurs when the soil is loaded from an initial σ’u1= 560 psf to σ’u2 = 3000 psf?

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(b) If you load the soil further, to σ’u3= 4000 psf, how much additional settlement occurs?

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(c) Finally, if you unload from 4000 psf back to σ’u4 = 3000 psf, what additional deformation (in feet) occurs?