Free Tool · EN 1997-1 §9 · EN 1992-1-1 · Retaining Wall Design
Retaining Wall Design Calculator
Stability and structural design for gravity, cantilever, and counterfort retaining walls per EN 1997-1 §9 (DA1) and EN 1992-1-1. Rankine or Coulomb earth pressure, Mononobe-Okabe seismic, groundwater table, RC stem/base-slab reinforcement.
Standards Compliance
EN 1997-1:2004 §9 — Retaining Structures
EN 1997-1 DA1 (C1+C2)
EN 1992-1-1:2004 §6.1 — RC Bending
EN 1992-1-1:2004 §6.2 — RC Shear VRd,c
Coulomb Ka / Rankine Ka
EN 1998-5 §E.3 — Mononobe-Okabe
Meyerhof-Vesić — Bearing Capacity
BS 8002 — Earth Retaining Structures
CIRIA C580 — Embedded Retaining Walls
FAQ
What stability checks does EN 1997-1 DA1 require?+
EN 1997-1 Design Approach 1 requires two combinations: C1 (A1+M1+R1, load factors γG=1.35/γQ=1.5) and C2 (A2+M2+R1, material factors γφ=1.25). The wall must satisfy sliding (Hd ≤ Rd), overturning (Mstab/Mdst ≥ 1.0), and bearing (σEd ≤ qRd). C2 typically governs sliding and overturning because material strengths are factored; C1 governs bearing.
Rankine vs Coulomb — which should I use?+
Rankine assumes a smooth vertical wall (δ=0) and level backfill; it gives conservative (higher) Ka values. Coulomb accounts for wall friction δ and inclined backfill, giving lower Ka. Use Rankine for preliminary design or smooth walls. Use Coulomb for rough concrete or brick walls where δ = φ/2 to 2φ/3 is justified. Both methods are valid per EN 1997-1.
What is the difference between gravity, cantilever, and counterfort walls?+
A gravity wall relies on its own mass for stability — typically used for H ≤ 4m. A cantilever (L-shaped RC) wall has a thin stem and base slab that act as a cantilever beam; the backfill weight on the heel adds to stability and it is efficient for H = 3–8m. A counterfort wall adds triangular RC buttresses (counterforts) at regular spacing behind the stem to reduce bending moments; used for H > 6m.
How is seismic earth pressure handled (Mononobe-Okabe)?+
When a seismic coefficient Kh > 0 is entered, the seismic active earth pressure Ka,E is computed using the Mononobe-Okabe method (EN 1998-5 §E.3). This increases the active thrust by ΔEa applied at 0.6H from the base. For non-seismic zones leave Kh = 0.
How is the RC stem designed?+
For cantilever and counterfort walls, the stem is modeled as a cantilever fixed at the base. The design moment MEd = Ea·hEa and the required reinforcement area As,req is calculated using EN 1992-1-1 §6.1 (parabolic-rectangular stress block). The shear check uses EN 1992-1-1 §6.2.2: VRd,c = (0.18/γc)·k·(100·ρl·fck)^(1/3)·bw·d. If VEd > VRd,c, shear links are required.
How does the groundwater table affect stability?+
When GWT depth is less than the total retained height, the submerged unit weight γ' = γ_soil − 10 kN/m³ is used for the soil below the water table. This reduces the active earth pressure compared to a dry case but also reduces vertical load. For drained analysis (effective stress), the hydrostatic water pressure on the wall should additionally be checked — this tool uses a simplified effective weight approach.