1. Solve the following problem. A structural engineer has hired you to design square concrete unembedded footings for a building, based only on capacity. Each footing will hold an axial

load of 120 kN. Your technicians have conducted lab tests on specimens sampled from the site, and they report the following profile: a 2-meter thick clay layer over a 7-meter thick clayey silt layer (the clayey silt layer lies over rock). The lab report reveals that the clay has a friction angle of 38 degrees and an undrained strength of 55 kPa, and that the clayey silt has a friction angle of 40 degrees and an undrained strength of 72 kPa. Determine the size of one of the footings, in meters, such that the critical (smallest) factor of safety against a capacity failure is between 3 and 3.3. Show all your work, organized, and circle your answer.