The site for a commercial building project has the surface elevation lowered 2 m to improve area grading for building access, parking, and drainage. Foundations for interior building columns will be...

The site for a commercial building project has the surface elevation lowered 2 m to improve area grading for building access, parking, and drainage. Foundations for interior building columns will be constructed at the level of the new ground surface. Each foundation is 1.5 m by 1.5 m square and imposes a bearing pressure of 200 kPa. What net stress increase results in the soil 1.25 m below the center of the foundation? Assume Boussinesq conditions apply and soil unit weight is 18 kN/m³.