Analyze slope resistance with practical inputs and instant outputs. Compare dry, wet, and seismic conditions. Make excavation decisions using clearer safety margins every day.
This calculator estimates dry, wet, and pseudo-static factor of safety for a pit wall using a simplified infinite slope screening method. It also estimates required cohesion and a maximum angle that still meets the selected target factor of safety.
| β (°) | φ (°) | c (kPa) | γ (kN/m³) | z (m) | ru | q (kPa) | kh | kv | Dry FoS | Wet FoS | Seismic FoS | Max Angle (°) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 24 | 35 | 25 | 19 | 10 | 0.10 | 10 | 0.05 | 0.00 | 1.909 | 1.730 | 1.524 | 24.3 |
This page uses a simplified infinite slope screening approach with Mohr-Coulomb shear strength. It is useful for early pit wall checks, sensitivity testing, and fast comparison of dry, wet, and seismic conditions.
Static factor of safety
FoS = [c + ((γz + q)cos²β − u)tanφ] / [(γz + q)sinβcosβ]
Pore pressure
u = ruγz
Pseudo-static terms
Neq = (γz + q)[(1 − kv)cos²β − khsinβcosβ]
Teq = (γz + q)[(1 − kv)sinβcosβ + khcos²β]
FoSeq = [c + (Neq − u)tanφ] / Teq
The maximum allowable angle is found by checking many trial angles until the governing factor of safety drops below the selected target.
It uses a simplified infinite slope screening model with Mohr-Coulomb strength. The method is practical for quick pit wall checks, but it does not replace a full geotechnical design study.
Many screening studies use targets near 1.3 to 1.5, but project rules vary. Use the value required by your engineer, mine plan, client standard, or local authority.
Yes, for screening. You can enter representative strength and load values for either material. Still, jointing, blasting damage, anisotropy, and benches may require a more detailed model.
Water raises pore pressure and lowers effective normal stress along the potential slip surface. That reduces frictional resistance and usually drops the factor of safety.
Seismic coefficients approximate earthquake loading during screening. They add driving demand and can lower resistance, helping you compare static and pseudo-static stability quickly.
No. Benching can help catch falls and reduce local runout, but overall stability still depends on geometry, drainage, material strength, and loading conditions.
No. Use it for planning and screening only. Final approval should come from qualified geotechnical review, site investigation, monitoring data, and a project-specific stability analysis.
Reduce the slope angle, lower water pressure through drainage, reduce surcharge, improve support, or revise excavation stages. Better material data can also change the design decision.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.