How to solve

$13-10$ A square footing foundation is required to carry a

column load of $100$ kN $($including the weight of

the foundation$).$ The footing will be installed

close to the ground surface on a uniform clay soil

having an undrained shear strength $($cohesion$)$

equal to $45$ kPa $.$ Assume that the angle of internal

friction is zero. The water table is deep. The soil

rigidity index is $9.$ Apply the extended bearing

capacity equation with a factor of safety of $3$ to

determine the required size foundation.