Slope stability: non-circular surfaces

The Stability module of CiviLab 7.1 has its own ribbon tab, organised in four groups: Bishop method, Spencer / Morgenstern-Price, Non-circular surfaces and Seismic. Each group has its own input window, list of calculations and sheets.

Surfaces

• specified polygon (typed points, ends on the ground surface);
• "three-block" search along a weak layer: active block, central block in the layer, passive block (NF P 94-270 §10.3, figures 10.3 and 10.4) — grid then direct search;
• slices cut at the polygon vertices and at layer changes;
• calculation by Spencer or Morgenstern-Price (force and moment equilibrium).

Geometry and soils

• soil layers defined by their top boundary, with γ, γsat, c′ / φ′ (drained) or cu (undrained);
• water table and surcharge at the crest;
• input window with a permanent scaled section and Excel import / export.

Eurocode 7 check

• factor of safety F compared with the required factor;
• NF P 94-270 §10: design approach 3 (A2 + M2 + R3), partial factors of annex C (γQ = 1.3; γφ′ = 1.25; γc′ = 1.25; γcu = 1.4), γR;d = 1.10 (§10.5), inequality 10.2.1 Fd ≥ γR;e·γR;d.

Results

• scaled sheet: layers, water table, surcharge, critical surface and slices, soil table and results;
• comparison Fellenius / Bishop / Spencer / Morgenstern-Price (with λ) on the critical surface;
• "Test data" pages with the slices of the critical surface.

Validation on published cases

Each published case was entered in CiviLab and compared with the reference value and with the GeoStudio SLOPE/W results (verification manual). Difference = (CiviLab − GeoStudio) / GeoStudio, same method.

See all validation results →

The other slope stability calculations

• Bishop method
• Spencer and Morgenstern-Price methods
• Seismic stability