A large tank structure $5$ m high is to be constructed on the site as shown

below on Figure $1.$ The intention is to fill the tank with water.

Determine the vertical total stress, vertical effective stresses and pore

water pressure at the centre point of both the clay layer and the sand layer $(***$please convert the density to unit weight. Please use the unit weight to do the calculation$)$

$($a$)$ before the tank is constructed

$($b$)$ Immediately after the tank is constructed

$($c$)$ Many years later assuming the tank remains full of water and all

consolidation in the ground due to filling the tank is complete.