Slope Stability Model and Landslide Susceptibility Using Geo-technical Properties of Soil - Semi-quantitative Approaches for Landslide Assessment and Prediction - page 176

Fig. 6.3 Landslide susceptibility under saturated condition

ðÞ ¼ r n tan / þ ð 6 : 17 Þ

Shear Strength C

where, r n = normal stress; / = friction angle; and C = cohesion of the soil.

6.4.3 Safety Factor Based Stability Classes

See Table 6.1 .

Table 6.1 The Stability Classes and Remarks
Safety factor (FS) Slope condition Remarks

FS < 1.5 Stable Only major destabilizing factors lead to instability

1.25 < FS < 1.5 Moderately stable Moderate destabilizing factor lead to instability

1 < FS < 1.25 Quasi stable Minor destabilizing factor lead to instability

FS < 1 Unstable Stabilizing factors are needed for stability