FullCalculator

Slope Stability Factor Calculator

Slope Stability Factor

Calculate the factor of safety for slope stability using the infinite slope method considering soil properties, slope angle, and water table.

Formula

FOS = Shear Strength / Shear Stress; Shear Strength = c + (Normal Stress - Pore Pressure) x tan(phi); Normal Stress = gamma x H x cos^2(beta); Shear Stress = gamma x H x sin(beta) x cos(beta)

Frequently Asked Questions

What factor of safety is considered stable?
A factor of safety of 1.5 or greater is generally considered stable for permanent slopes. Temporary construction slopes may use 1.25. Values below 1.0 indicate the slope will fail.
How does water affect slope stability?
Water is the most common trigger for landslides. It increases pore water pressure, reduces the effective normal stress, and thus reduces the shear strength along the failure plane, dramatically lowering the factor of safety.
What is the infinite slope method?
The infinite slope method analyzes a long, uniform slope by examining a thin slice of soil parallel to the surface. It works well for shallow, planar failures and is the simplest slope stability analysis method.

You may also need