Eurocode 7 Sliding Resistance Calculator (EN 1997-1)

Eurocode 7 sliding resistance – design principles

Eurocode 7 (EN 1997-1) requires that the design effect of actions causing sliding, E_d, does not exceed the design sliding resistance, R_d, along the potential sliding plane (usually the base of a footing or retaining structure):

Sliding resistance formula used in this calculator

A common Eurocode 7 expression for the characteristic sliding resistance along a horizontal base is:

where:

• V_k – characteristic vertical action on the base (kN)
• δ_k – characteristic interface friction angle between base and soil (°)
• c_R,k – characteristic cohesion along the sliding plane (kPa)
• φ_R,k – characteristic friction angle along the sliding plane (°)
• A – base area (m²)

The cohesion term is expressed in kN by multiplying by area and using the trigonometric relationship for the mobilised shear strength along the plane.

In design, partial factors are applied to actions, material parameters and/or resistances depending on the chosen design approach (DA1, DA2, DA3) and National Annex. This calculator lets you work directly with design values:

• V_d, δ_d, c_R,d, φ_R,d – design values (already factored) of the corresponding quantities
• R_p,d – additional design resistance (e.g. passive earth pressure, shear keys, anchors) (kN)
• γ_R – partial factor on resistance (typically 1.0–1.3)

Factor of safety against sliding

Instead of a single global factor of safety, Eurocode 7 uses partial factors. However, it is often convenient to compute an apparent factor of safety:

The calculator reports both R_d and FS_sliding and indicates whether the condition E_d ≤ R_d is satisfied.

How to use the Eurocode 7 sliding resistance calculator

1. Select the value type. Choose whether you are entering design values or characteristic values. If you use characteristic values, apply the appropriate partial factors to obtain design values or use γ_R to factor the resistance.
2. Enter the design horizontal action E_d. This is the resultant horizontal action at the base (e.g. from earth pressure, surcharge, seismic, etc.).
3. Enter the design vertical action V_d. Include permanent and variable vertical loads according to the design combination.
4. Define interface and soil parameters. Provide δ (interface friction angle), φ_R (friction angle along the plane), cohesion c_R and base area A.
5. Set γ_R. Use the value from your National Annex. Set γ_R = 1.0 if you already work with fully factored design resistances.
6. Optional: add passive/structural resistance. Tick the box if you want to include additional design resistance R_p,d (e.g. from a shear key or passive wedge).
7. Click “Calculate”. The tool returns R_d, FS_sliding and a clear pass/fail message.

Worked example (illustrative)

Assume a spread footing with:

• E_d = 200 kN (horizontal)
• V_d = 1500 kN (vertical)
• δ_d = 25°, φ_R,d = 30°
• c_R,d = 0 kPa (no cohesion along base)
• A = 25 m², γ_R = 1.1, R_p,d = 0

Then:

In practice, you would use design values and partial factors consistent with your National Annex and design approach.

Limitations and good practice

• This tool assumes a planar sliding surface at the base; it does not model complex 3D failure mechanisms.
• For retaining walls, check overturning, bearing capacity and structural capacity in addition to sliding.
• For seismic design situations, use the appropriate combination factors and partial factors from EN 1998 and the National Annex.
• Always verify results with engineering judgement and, where necessary, more detailed numerical or analytical methods.

FAQ

What is sliding resistance in Eurocode 7?

Sliding resistance is the design resistance against horizontal sliding along a potential slip plane, usually at the base of a foundation or retaining structure. It is provided by base friction and any additional passive or structural resistance and must be checked so that E_d ≤ R_d.

Which partial factors should I use?

Partial factors on actions, material parameters and resistances are given in EN 1997-1 and the relevant National Annex. They depend on the design approach (DA1, DA2, DA3) and the design situation (persistent, transient, accidental, seismic). Always follow the values specified in your country’s National Annex.

Can I use this calculator for both foundations and retaining walls?

Yes. As long as the sliding mechanism can be represented by a resultant horizontal action E_d and a resultant vertical action V_d on a planar base, the same formulation applies. For retaining walls, ensure that the base geometry and soil parameters used are consistent with the assumed failure mechanism.