What primarily determines the safety factor of a slope?

The safety factor of a slope is primarily determined by the relationship between the inherent strength of the slope material and the stresses acting upon it. This concept involves a mathematical comparison where the strength (the ability of the material to resist failure) is evaluated against the stresses that are applied to the slope (which can be due to factors like weight, water saturation, or seismic activity). When engineers and geologists assess slope stability, they specifically look at this balance to understand whether a slope is at risk of failure. A safety factor greater than one typically indicates a stable slope, as the material strength exceeds the stress, while a factor less than one signals potential instability.

While material composition, topography, and vegetation cover play significant roles in influencing both the strength and stress components, they do not inherently determine the safety factor in the same direct manner as the strength versus stress comparison. Material composition affects the strength and cohesion, topography influences the angles and forces acting on the slope, and vegetation can contribute to soil stability or added weight. However, the fundamental safety evaluation relies on the comparative analysis of strength to stress.