The soil profile at a site consists of a $5 \: m$ thick sand layer underlain by a $c - \phi$ soil as shown in figure. The water table is found $1 \: m$ below the ground level. The entire soil mass is retained by a concrete retaining wall and is in the active state. The back of the wall is smooth ans vertical. The total active earth pressure (expressed in $kN/m^2$) at point A as per Rankine’s theory is __________
