Road Cut Sandbox V1.0

Planar Rock Slope Stability: Cohesion and Water Pressure

The factor of safety (FoS) includes cohesion c and the pore pressure ratio ru. FoS is calculated using the slope height H and an assumed rock unit weight gamma = 25 kN/m³. The Mohr diagram shows the effective stress state (sigma', tau) on the bedding plane.

Bedding angle alpha (0–180°, from horizontal) 30°

Road cut dip beta (80–180°, from horizontal) 110°

Friction angle phi on bedding 35°

Cohesion c on bedding (kPa) 5 kPa

Pore pressure ratio ru (u / gamma H) 0.00

Slope height H (m) 20 m

Factor of safety FoS: -

gamma = 25 kN/m³. alpha_eff is the acute angle of bedding dip (0–90°). FoS is based on the classical infinite slope model for planar sliding in rock with cohesion and pore pressure.