Enter the internal friction angle of the material into the At-Rest Earth Pressure Coefficient (K0) Calculator. This calculator uses Jaky’s approximation, K0 ≈ 1 − sin(φ), which is commonly applied to normally consolidated soils under typical at-rest (no lateral strain) conditions. It is not the active (Ka) or passive (Kp) earth pressure coefficient.
At-Rest Earth Pressure Coefficient (K0) Formula
The following example problem outlines the steps and information needed to calculate the at-rest earth pressure coefficient using Jaky’s approximation.
K_0 \approx 1-\sin(\varphi)
Variables:
- K0 is the at-rest earth pressure coefficient (dimensionless)
- φ is the internal friction angle of the material (in degrees)
To estimate the at-rest earth pressure coefficient for a normally consolidated soil, subtract the sine of the internal friction angle from 1 (Jaky’s approximation).
How to Calculate At-Rest Earth Pressure Coefficient (K0)?
The following steps outline how to calculate the at-rest Earth Pressure Coefficient (K0) using Jaky’s approximation.
- First, determine the internal friction angle of the material, φ (in degrees).
- Next, use the formula from above: K0 ≈ 1 − sin(φ).
- Finally, calculate K0 (dimensionless).
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem:
Use the following variables as an example problem to test your knowledge.
Internal friction angle of the material, φ = 45°
K0 ≈ 1 − sin(φ) = 1 − sin(45°) ≈ 1 − 0.7071 ≈ 0.2929
