Geotechnical Engineering
Retaining Wall Pressure Calculator
Estimate active retaining wall pressure, surcharge contribution, and drainage sensitivity.
Parameter sketch
Retaining wall load components
Labels update with the current input values so the formula symbols stay tied to the geometry.
Result
Estimated active force: 848.03 force/length
Ka
0.307
K0
0.47
Kp
3.255
Selected K
0.307
Base pressure
221.23
Total force
848.03
Resultant above base
2
Drainage multiplier
1
Adjusted total active force
848.03
Surcharge contribution
184.2
Step-by-step calculation
- Compute pressure coefficients for phi=32 deg.
- Select K=0.307 for active wall condition.
- Soil force = 0.5 x 0.307 x 120 x 6^2 = 663.68.
- Surcharge force = 0.307 x 100 x 6 = 184.36.
What this means
Drained granular backfill is assumed; water pressure still needs a separate check where drainage may clog or fail.
Formula Used
Pa = 0.5 Ka gamma H^2 + KaqH
Step-by-Step Example
A 6 ft drained wall with phi=32 deg, gamma=120 pcf, and 100 psf surcharge has about 859 lb/ft active force.
Engineering Notes
Check units, assumptions, boundary conditions, groundwater, drainage, and whether the simplified method is appropriate before using a result in any project decision.
FAQ
Does this include water pressure?
No. Undrained or clogged-drain conditions need separate hydrostatic pressure checks.