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Soil-nailed slope stability and design

Enter the geometry, soil layers and nail arrangement to assess the reinforced slope. The calculation includes nails that cross the slip surface and provides a facing check for review.

Open the tool

The app and these introductory pages are available in Portuguese, English and Spanish.

What the tool calculates

  • Factor of safety from the method of slices, including the contribution of nails crossing the slip surface
  • Force in each nail limited by pullout resistance or steel yielding
  • Search rejects surfaces that do not intersect the ground surface or are invalid for the model
  • Technical references from NBR 16920-2:2021 and FHWA GEC-7

What you enter

  • Slope geometry and soil nail arrangement
  • Nail pullout resistance and steel yield strength
  • Soil strength parameters

What you receive

  • Factor of safety including nail resistance
  • Mobilised force per nail
  • Facing check

References and limits of applicability

  • ABNT NBR 16920-2:2021 — Reinforced soil walls and slopes, Part 2: soil nailing; nails are passive reinforcement, distinct from the active ground anchors covered by NBR 5629
  • FHWA-NHI-14-007 (GEC-7) — supplementary technical basis for the method

Checks and considerations

  • Surfaces that do not intersect the ground surface are rejected by the search
  • Pullout resistance may limit nail capacity before the steel yields

How it works

The model combines slice equilibrium with the contribution of nails crossing the surface under analysis. Available nail force depends on the anchored length, pullout resistance, steel properties and inclination. The search results and facing check must be assessed against the project's geotechnical parameters and construction conditions.

Example of use

To assess reinforcement of a cut slope, enter the soil layers and nail arrangement. Compare nail lengths and spacings, identify which nails cross the critical surface, and review the factor of safety and facing checks.

Generated documents

These documents are assembled within your project using data from the corresponding tools.

  • Geotechnical calculation report — Combine calculation reports for soil stress bulbs, retaining walls, reinforced soil walls, slope stability and soil-nailed slopes in one PDF. The document consolidates saved calculations without repeating or cross-checking the individual tools' verifications.

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