Submerged Unit Weight given Weighted and Effective Friction Angle Calculator

Submerged Unit Weight Formula:

\[ \gamma' = \frac{\phi_{IF} \times \left(\frac{180}{\pi}\right)}{\frac{\phi' \times \left(\frac{180}{\pi}\right)}{f_s \times \gamma_{sat}}} \]

Weighted Friction Angle for Internal Friction:

rad

Effective Angle of Internal Friction:

rad

Factor of Safety:

Saturated Unit Weight:

kN/m³

Submerged Unit Weight (kN/m³):

1. What is Submerged Unit Weight?

Definition: Submerged Unit Weight is the effective weight of soil per unit volume when submerged in water, accounting for buoyancy effects.

Purpose: It's crucial for geotechnical engineering calculations involving soil stability under water-saturated conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \gamma' = \frac{\phi_{IF} \times \left(\frac{180}{\pi}\right)}{\frac{\phi' \times \left(\frac{180}{\pi}\right)}{f_s \times \gamma_{sat}}} \]

Where:

\( \gamma' \) — Submerged unit weight (kN/m³)
\( \phi_{IF} \) — Weighted friction angle for internal friction (radians)
\( \phi' \) — Effective angle of internal friction (radians)
\( f_s \) — Factor of safety (dimensionless)
\( \gamma_{sat} \) — Saturated unit weight (kN/m³)

Explanation: The formula calculates the submerged unit weight by considering the weighted friction angle, effective friction angle, safety factor, and saturated unit weight.

3. Importance of Submerged Unit Weight Calculation

Details: Accurate calculation is essential for designing foundations, retaining walls, and slope stability analysis in water-saturated soils.

4. Using the Calculator

Tips: Enter all required values in radians (for angles), with default values provided for factor of safety (2.8) and saturated unit weight (9.98 kN/m³).

5. Frequently Asked Questions (FAQ)

Q1: Why is the factor of safety important?
A: The factor of safety accounts for uncertainties in material properties and loading conditions, ensuring structural stability.

Q2: What's a typical value for saturated unit weight?
A: Most soils have saturated unit weights between 18-22 kN/m³, but this can vary significantly based on soil type.

Q3: How do I convert degrees to radians?
A: Multiply degrees by π/180 (or use our Angle Conversion Calculator).

Q4: When would I need to adjust the factor of safety?
A: Adjust based on project requirements, risk tolerance, and regulatory standards (typically 1.5-3.0 for most applications).

Q5: Does this calculation account for soil variability?
A: The weighted friction angle helps account for variability, but site-specific testing is recommended for critical projects.