Slope Stability

Slope Stability

Slope stability analysis assesses the safety of natural or man-made slopes against failure (sliding of a soil mass).

Infinite Slope Analysis

Assumes the slope extends indefinitely and the failure plane is parallel to the surface.

Factor of Safety (Infinite Slope)

For a slope with angle β\beta and soil friction ϕ′\phi', with seepage parallel to slope: FS=γ′γsattan⁡ϕ′tan⁡βFS = \frac{\gamma'}{\gamma_{sat}} \frac{\tan \phi'}{\tan \beta} For dry slope: FS=tan⁡ϕ′tan⁡βFS = \frac{\tan \phi'}{\tan \beta}

Finite Slope Analysis

Used for specific slope geometries (embankments, cuts). Assumes a circular or non-circular failure surface.

Method of Slices (Fellenius/Bishop)

The failure mass is divided into vertical slices.

  • Ordinary Method of Slices: Ignores inter-slice forces (Conservative).
  • Bishop's Simplified Method: Considers inter-slice normal forces (More accurate). FS=∑Resisting Moments∑Driving MomentsFS = \frac{\sum \text{Resisting Moments}}{\sum \text{Driving Moments}}
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