Geotechnical Engineering

Lateral Earth Pressure Calculator

Estimate active, at-rest, or passive lateral earth pressure for simple drained backfill cases.

Engineering schematic

Lateral earth-pressure components

Static symbolic figure. Enter project values in the calculator fields below.

Vertical wall with level backfill, wall height H, surcharge q, separate triangular soil and rectangular surcharge pressure distributions, and their resultants at H over 3 and H over 2. — Symbols
H
retained height
q
uniform surface surcharge
K
selected Kₐ, K₀, or Kₚ pressure coefficient
γ, φ
soil unit weight and friction angle

Result

Total lateral force: 2833.33 force/length

0.333

0.5

Selected K

0.333

Base pressure

400

Total force

2833.33

Resultant above base

3.33

Step-by-step calculation

Rankine coefficients
$K_a=0.333,\quad K_0=0.5,\quad K_p=3$
Selected pressure coefficient
$K=0.333$
Soil-weight resultant
$P_\gamma=\frac{1}{2}(0.333)(120)(10)^2=2000$
Surcharge resultant
$P_q=(0.333)(250)(10)=833.33$

What this means

Higher wall movement restraint increases pressure; passive pressure should be used cautiously with deformation compatibility.

Assumptions

Rankine pressure coefficients
Level drained granular backfill
No wall friction or seismic increment

Formula Used

P_a=\frac{1}{2}K\gamma H^2+KqH

Step-by-Step Example

A 10 ft wall with gamma=120 pcf, phi=30 deg, and 250 psf surcharge gives about 2,217 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

What is K0?

K0 is at-rest pressure used when the wall cannot move enough to mobilize active conditions.