A $4 \mathrm{~m}$ thick layer of normally consolidated clay has an average void ratio of $1.30 .$ Its compression index is 0.6 and coefficient of consolidation is $1 \mathrm{~m}^{2} / \mathrm{yr}$. If the increase in vertical pressure due to foundation load on the clay layer is equal to the existing effective overburden pressure, the change in the thickness of the clay layer is
A $4 \mathrm{~m}$ thick layer of normally consolidated clay has an average void ratio of $1.30 .$ Its compression index is 0.6 and coefficient of consolidation is $1 \mathrm{~m}^{2} / \mathrm{yr}$. If the increase in vertical pressure due to foundation load on the clay layer is equal to the existing effective overburden pressure, the change in the thickness of the clay layer is