1. What is Submerged Unit Weight?

Definition: Submerged unit weight is the effective unit weight of soil when it's submerged under water, accounting for buoyancy effects.

Purpose: It's crucial for analyzing soil stability in water-saturated conditions, such as in seepage analysis and slope stability calculations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( yS \) — Submerged unit weight (kN/m³)
• \( σn \) — Normal stress in soil (Pa)
• \( Fu \) — Upward force due to seepage (Pa)
• \( z \) — Depth of prism (m)
• \( i \) — Angle of inclination to horizontal (°)

Explanation: The formula accounts for the net vertical stress divided by the depth and adjusted for slope angle.

3. Importance of Submerged Unit Weight Calculation

Details: Accurate calculation is essential for designing stable foundations, retaining walls, and slopes in water-saturated soils.

4. Using the Calculator

Tips: Enter all required values in consistent units. The tolerance field (default ±5%) helps account for measurement uncertainties.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical submerged unit weight range?
A: For most soils, it ranges between 8-11 kN/m³, but can vary based on soil type and saturation.

Q2: When is upward force in seepage significant?
A: In conditions with high hydraulic gradients, such as near dams, retaining walls, or during rapid drawdown.

Q3: How does angle of inclination affect the result?
A: Steeper angles reduce the effective normal stress component, decreasing submerged unit weight.

Q4: Why include a tolerance percentage?
A: Soil properties and measurements often have variability; tolerance provides a realistic range.

Q5: How to measure normal stress in soil?
A: Use pressure cells or calculate from overburden pressure (unit weight × depth).

Submerged Unit Weight given Upward Force Calculator© - All Rights Reserved 2025