How do you calculate the factor of safety?

The calculation of the factor of safety is a crucial aspect in evaluating the stability of a system, particularly in geotechnical engineering. The correct approach to determining the factor of safety is by dividing the resisting forces by the driving forces.

Resisting forces represent the forces that counteract movements, such as friction and cohesion, while driving forces are those that promote movement or potential failure, such as gravity and external loads. By taking the ratio of resisting forces to driving forces, you obtain a quantifiable measure of safety. A factor of safety greater than one indicates that the system is stable because the resisting forces are sufficient to counter the driving forces, whereas a factor of safety less than one suggests failure is imminent, as the driving forces outweigh the resistance.

Understanding this balance is essential for engineers and geologists as it aids in designing structures and assessing risks related to landslides, slope stability, and other geotechnical phenomena.