Figure $1$

In the second option, he plans to construct the $5-$m road embankment together with a $3-$m thick fill layer as surcharge $($see Figure $3).$ Vertical drains $($size of $100mm4mm)$ will be installed at $2\mathrm{.}8m$ spacing in a square pattern prior to construction of the embankment.

$(5)$ When will the clay layer complete its primary consolidation under the weight of the road embankment and the surcharge fill $($assume there is no smear, no well resistance and no vertical flow through the clay layer$)$

The $3-$m surcharge fill will be removed after the clay layer has completed primary consolidation under the weight of the road embankment and the surcharge fill.

$(6)$ At time of removal of surcharge, what is the effective surcharge ratio, $R_s^{\text{'}},$ of the whole clay layer with respect to effective final vertical stress under the $5-m$ road embankment? The

$2$

design engineer divides the clay layer into $4$ equal sublayers in his estimate of $R_5.$ Please fill in the table with supporting calculations.

$\backslash$table$[[\backslash$table$[[$Thickness of$],[$Sublayer $($m$)]],\backslash$table$[[$Mid$-$depth of$],[$Sublayer $(m)$