Q$2$:

A storage facility with dimensions $6m30m$ will be founded on a mat foundation i$.$e$.$ a slab, that for practical purposes

can be consider as an infinite strip footing. The embedment depth of the foundation cannot exceed $D=1m,$ for practical

reasons. The foundation subsoil consists of a soft to medium$-$stiff saturated clay layer, with the properties depicted in

the figure below. Preliminary bearing capacity estimations resulted in a short$-$term failure stress $q=180$kPa, which is

lower than the required ultimate limit state structure stress provided by the Structural Engineer $p=200$kPa.

As the dimensions of the footing are fixed on the geometry of the facility, improvement measures have to be

implemented to increase the bearing capacity of the subsoil. The Geotechnical Engineer proposed the replacement of

the clay with coarse$-$grained well$-$compacted material, as the most cost$-$effective ground improvement solution.

Determine the minimum required thickness of the improvement layer to increase the bearing capacity to acceptable

levels, while taking into account the following.

Consider for simplicity the unit weight of both the clay and the foundation improvement layer to be equal to

$=18k\frac{N}{m^3}.$