First calculate the line of action of the Resultant force ( e ) from centre of the base.

(No Tension will develop at the heel)

The pressure at the toe of the wall must not exceed the allowable bearing capacity of the soil. The pressure at the base is assumed to be linear. The max. Pressure at the Toe & min at the Heel is given by:

should be less than the Safe bearing capacity( ) of the soil & should not be Tensile in any case. Tension is not desirable. The tensile strength of the soil is very small and tensile crack would develop. The effective base area is reduced.