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🪨 Hold Back the Soil

A gravity retaining wall holds back a fixed soil backfill. Your only lever is the wall's base width — too narrow and the soil pushes it over, too wide and you've poured needless concrete. Find the lightest wall that still safely resists overturning. Real Rankine earth pressure, no faking it.

Site

Backfill: H = 4.0 m, γ = 18 kN/m³, φ = 30°

Wall: rectangular gravity wall, γ_concrete = 24 kN/m³

Your Wall

Base width B 1.50 m

Live Result

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Overturning FS

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Wall Weight (kN/m)

🎯 Goal: find the narrowest wall that still keeps overturning FS ≥ 1.5 — the standard minimum used in practice.

This game runs the exact same Rankine active earth pressure formula (engine/earth-pressure.js → activePressure) used elsewhere on this platform, verified against a clean hand-calculated reference case (φ=30°, γ=18, H=4m → Ka=0.3333, Pa=48.0 kN/m — exact match) before publishing. The overturning check is simplified (moment about the toe from active pressure vs. wall self-weight only — no passive resistance, base friction, or bearing check) for game clarity, not a substitute for real retaining wall design.

Method

Rankine (1857)Ka = (1−sinφ)/(1+sinφ); Pa = ½·Ka·γ·H², acting at H/3 above the base.

Overturning FSFS = (resisting moment about toe) / (overturning moment about toe) = [W·(B/2)] / [Pa·(H/3)].

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