Design Code

Design Approach (EN)

Wall Geometry

H — wall stem height (m)

B — base width (m)

t_base — base thickness (m)

t_stem — stem thickness (m)

heel — heel projection (m)

toe — toe projection (m)

Soil & Surcharge

γ_soil — unit weight (kN/m³)

γ_conc — concrete (kN/m³)

φ' — friction angle (°)

c — cohesion (kPa)

δ — wall friction (°)

q_s — surcharge (kN/m²)

Groundwater table depth (m, from top; blank = dry)

Foundation

q_a — allowable bearing (kPa)

Stability Results EN 1997-1

PASS

Overturning

3.57 PASS

1 req28.01%

Sliding

2.04 PASS

1 req49.02%

Bearing

105.26 kPa PASS

limit11.16%

K_a — active pressure coeff.0.291

E_a — active thrust (kN/m)52.36 kN/m

V — total vertical (kN/m)209.96 kN/m

M_res — resisting moment (kNm/m)406.63 kNm/m

M_over — overturning moment (kNm/m)113.77 kNm/m

Eccentricity e (m)0.21 m

σ_max — max base pressure (kPa)105.26 kPa

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FAQ

What is the minimum overturning factor of safety?

It depends on the design code: EN 1997-1 requires M_stab/M_dst ≥ 1.0 (with partial factors applied to actions/materials), GB 50007-2011 requires K_overturn ≥ 1.5 (unfactored working loads), and IS 14458 requires FOS ≥ 2.0 (working loads). The GB and IS values appear higher because they use unfactored loads, while EN applies load/material factors before the check.

What sliding resistance factors are required?

EN 1997-1 requires R_d/H_d ≥ 1.0 (after partial factors), GB 50007 requires K_slide ≥ 1.3, and IS 14458 requires FOS_slide ≥ 1.5. Passive resistance on the toe can be counted in all three codes but should be conservatively reduced or ignored for permanent structures.

How is the active earth pressure calculated?

This calculator uses the Coulomb formula with the Rankine simplification for a vertical wall back with level backfill (δ=0, β=0). Ka = tan²(45−φ/2). For sloped backfill or inclined wall faces, the full Coulomb equation is used: Ka = sin²(α+φ) / (sin²α·sin(α−δ)·[1+√(sin(φ+δ)·sin(φ−β)/sin(α−δ)·sin(α+β))]²).

How is bearing capacity checked?

For EN 1997-1, the Meyerhof-Vesić bearing capacity equation is used (q_ult = c·Nc + q_f·Nq + 0.5·γ·B_eff·Nγ) and the design resistance Q_Rd = q_ult/γ_Rv must exceed σ_max. For GB 50007, the allowable stress method is used: σ_max ≤ 1.2·q_a. For IS 14458, the user inputs the safe bearing capacity (already includes FOS 2.5–3.0 per IS 6403), and σ_max must not exceed it.

What is the significance of base pressure eccentricity?

The resultant of all vertical loads does not act at the centre of the footing base when there is an overturning moment. The eccentricity e = B/2 − M_net/V_total. If e > B/6 (the kern limit), the linear pressure distribution predicts tension at the heel edge, which soil cannot carry. All three codes require the resultant to remain within the middle third of the base (e < B/6).

Does this tool check reinforced concrete design?

This calculator focuses on geotechnical stability (sliding, overturning, bearing). For RC design of the stem, heel slab, and toe slab per EN 1992-1-1, use the structural checks in the FrameAI pipeline — it calculates stem bending moment, required reinforcement, shear in heel/toe, and crack width all in one pass from your PDF drawing set.

Retaining Wall Design

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