Cohesion given Submerged Unit Weight Calculator

Cohesion of Soil Formula:

\[ C_s = \left(FS - \frac{\tan\left(\frac{\phi \cdot \pi}{180}\right)}{\tan(i)}\right) \times (\gamma' \cdot z \cdot \cos(i) \cdot \sin(i)) \]

Factor of Safety:

Angle of Internal Friction (φ):

radians

Angle of Inclination (i):

radians

Submerged Unit Weight (γ'):

N/m³

Depth of Prism (z):

meters

Cohesion of Soil (kPa):

1. What is Cohesion given Submerged Unit Weight?

Definition: This calculator determines the cohesion of soil based on factor of safety, internal friction angle, inclination angle, submerged unit weight, and depth of prism.

Purpose: It helps geotechnical engineers evaluate soil stability for slope stability analysis and foundation design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C_s = \left(FS - \frac{\tan\left(\frac{\phi \cdot \pi}{180}\right)}{\tan(i)}\right) \times (\gamma' \cdot z \cdot \cos(i) \cdot \sin(i)) \]

Where:

\( C_s \) — Cohesion of Soil (kPa)
\( FS \) — Factor of Safety
\( \phi \) — Angle of Internal Friction (radians)
\( i \) — Angle of Inclination (radians)
\( \gamma' \) — Submerged Unit Weight (N/m³)
\( z \) — Depth of Prism (meters)

Explanation: The formula calculates soil cohesion by considering the balance between resisting and driving forces in a submerged slope.

3. Importance of Cohesion Calculation

Details: Accurate cohesion values are critical for slope stability analysis, retaining wall design, and foundation engineering in saturated soil conditions.

4. Using the Calculator

Tips: Enter all required parameters. Default values are provided. All inputs must be positive values. Results are in kPa.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical factor of safety for slopes?
A: Common values range from 1.3 to 1.5 for temporary slopes and 1.5 to 2.0 for permanent slopes.

Q2: How do I measure angle of internal friction?
A: It's typically determined through direct shear tests or triaxial tests in a geotechnical laboratory.

Q3: What affects submerged unit weight?
A: Soil particle density, void ratio, and degree of saturation all influence submerged unit weight.

Q4: Why is cohesion important in slope stability?
A: Cohesion provides shear strength that helps slopes resist failure, especially in fine-grained soils.

Q5: Can this calculator be used for dry soils?
A: No, this specifically calculates for submerged conditions. Use different formulas for dry or partially saturated soils.