Retaining wall stability calculator

Inputs in the worked example

The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.

Worked example — results

• ✗ Sliding FS ≥ 1.5
• ✓ Overturning FS ≥ 2.0
• ✓ Resultant in middle third
• ✓ Toe pressure ≤ qa

Method, formulas and assumptions

• Pa = ½ Ka γ H², Pq = Ka q H, H to the underside of the base
• Weights: stem, base, soil and surcharge over the heel (passive resistance ignored)
• FS sliding = V tan δ / ΣH; FS overturning = ΣMr/ΣMo about the toe
• e = B/2 − (Mr − Mo)/V; q = V/B (1 ± 6e/B)
• AS 4678 uses factored limit states; these working-stress factors are for preliminary sizing.

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