PE Civil Engineering Exam Prep

Answer: C - The equation (FS_o = resisting moment / overturning moment) is used for evaluating a retaining structure’s factor of safety with respect to overturning. Typically, a minimum factor of safety of 2.0 to 3.0 is considered necessary for a retaining wall to resist rotating outward around the toe of the wall. FS_o is expressed as follows:

FS_o = ∑Mr / ∑Mo

Where ∑Mr is the sum of the resisting moments around the toe and ∑Mo is the sum of the overturning moments around the toe