Question

At a reclamation site for which the soil strata is shown in figure, 3 m thick layer of a fill material is to be laid instantaneously on the top surface.

If the coefficient of volume compressibility $m_v$ for clay is $2.2\times {10}^{-4}{m}^2/kN$ the consolidation settlement of the clay layer due to placing of fill material will be

• A. 69.5 mm
• B. 139 mm
• C. 228 mm
• D. 278 mm

Answer 1

The correct option is B 139 mm

Coefficient of volume compressibility,

$m_v=2.2\times {10}^{-4}{m}^2/kN$

Increase in stress due to 3 m thick fill material layer

$\Delta \sigma =3{\gamma }_{fill}$

$=3\times 21$

$=63kN/m^2$

Thickness of clay layer,

H = 10 m

Settlement,

$\Delta H=H{m}_v\Delta \sigma$

$=10\times 2.2\times {10}^{-4}\times 63m$

= 138.6 mm

= 139 mm