GATE Civil Engineering (CE) 2020 Shift 1 Solved Paper

A $10\mathit{m}$ thick clay layer is resting over a $3\mathit{m}$ thick sand layer and is submerged. A fill of 2 $\mathit{m}$ thick sand with unit weight of $20\mathit{k}\mathit{N}/{\mathit{m}}^3$ is placed above the clay layer to accelerate the rate of consolidation of the clay layer. Coefficient of consolidation of clay is $9\times {10}^{-2}{\mathit{m}}^2$/year and coefficient of volume compressibility of clay is $2.2\times {10}^{-4}{\mathit{m}}^2/\mathit{k}\mathit{N}$. Assume Taylor's relation between time factor and average degree of consolidation.The settlement (in mm. round off to two decimal places) of the clay layer, 10 years afterthe construction of the fill, is