Effective Normal Stress given Saturated Unit Weight Calculator

Effective Normal Stress Formula:

\[ \sigma' = (\gamma_{sat} - \gamma_w) \times z \times \cos^2(i) \]

Saturated Unit Weight of Soil:

kN/m³

Unit Weight of Water:

kN/m³

Depth of Prism:

Angle of Inclination:

degrees

Effective Normal Stress (kPa):

Definition: Effective normal stress is the stress carried by the soil skeleton, which controls soil strength and deformation characteristics.

Purpose: It's essential for analyzing slope stability, bearing capacity, and settlement in geotechnical engineering.

The calculator uses the formula:

\[ \sigma' = (\gamma_{sat} - \gamma_w) \times z \times \cos^2(i) \]

Where:

Explanation: The formula accounts for buoyant unit weight and the inclination effect on stress distribution.

Details: Proper calculation is crucial for designing stable foundations, retaining walls, and assessing slope stability.

Tips: Enter saturated unit weight, water unit weight (default 9.81 kN/m³), depth, and inclination angle. All values must be ≥ 0 with angle ≤ 90°.

Q1: Why subtract water unit weight?
A: This accounts for buoyancy effects in saturated soils where water pressure reduces the effective stress.

Q2: What's a typical saturated unit weight?
A: Common values range from 18-22 kN/m³ for most soils, but can vary significantly.

Q3: Why the cos²(i) term?
A: This accounts for stress reduction on inclined planes - normal stress decreases as slope angle increases.

Q4: How does depth affect the result?
A: Effective stress increases linearly with depth in homogeneous soil.

Q5: What if my soil is unsaturated?
A: This calculator is for saturated conditions only. Different formulas apply for unsaturated soils.