Cantilever Concrete Retaining Wall Stem & Footing Calculator
Calculate structural cantilever concrete retaining wall dimensions, footing slab width and thickness, Rankine active lateral earth pressure, and overturning safety factors.
Calculated Results
Frequently Asked Questions
What is the standard rule-of-thumb ratio for cantilever retaining wall footings?
Structural engineering standards specify: (1) Footing Width = 0.50 to 0.70 times the total wall height H, (2) Footing Thickness = roughly 0.10 times H (minimum 12 inches), and (3) Base Stem Thickness = roughly 1 inch per foot of height (minimum 8 to 10 inches).
What safety factor is required against overturning and sliding?
Building codes strictly mandate a Minimum Safety Factor of 1.50 against overturning (Resisting Moment / Overturning Moment > 1.50) and 1.50 against base sliding (Friction Resistance / Lateral Soil Thrust > 1.50).
How does Rankine active earth pressure (Ka) calculate lateral thrust?
Under Rankine's theory, active earth pressure coefficient Ka = (1 - sin φ) / (1 + sin φ). The triangular lateral soil pressure increases with depth; total resultant force P_a = 0.5 × Ka × gamma × H^2, acting at H/3 above the footing.
Why is a shear key required on the bottom of a retaining wall footing?
If the friction between concrete and soil is insufficient to achieve the 1.5 sliding safety factor, a concrete shear key extends downward into firm soil below the footing to mobilize passive earth resistance.