Cohesion of Soil given Submerged Unit Weight Calculator

Cohesion of Soil Formula:

\[ C_s = \frac{h_c}{\frac{(\sec(i))^2}{\gamma' \times (\tan(i) - \tan(\phi))}} \]

Critical Depth (hc):

Angle of Inclination (i):

rad

Submerged Unit Weight (γ'):

N/m³

Angle of Internal Friction (φ):

rad

Tolerance:

Cohesion of Soil (Cs): kPa

Tolerance Range (±5%): kPa

1. What is Cohesion of Soil given Submerged Unit Weight?

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

Purpose: It helps geotechnical engineers and soil scientists evaluate soil stability and shear strength in submerged conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C_s = \frac{h_c}{\frac{(\sec(i))^2}{\gamma' \times (\tan(i) - \tan(\phi))}} \]

Where:

\( C_s \) — Cohesion of Soil (kPa)
\( h_c \) — Critical Depth (m)
\( i \) — Angle of Inclination (rad)
\( \gamma' \) — Submerged Unit Weight (N/m³)
\( \phi \) — Angle of Internal Friction (rad)

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

3. Importance of Soil Cohesion Calculation

Details: Proper cohesion estimation is crucial for slope stability analysis, foundation design, and earthwork construction in wet conditions.

4. Using the Calculator

Tips: Enter all required parameters with correct units. The tolerance field (default ±5%) allows you to specify an acceptable range for the result.

5. Frequently Asked Questions (FAQ)

Q1: What is typical cohesion value for different soil types?
A: Clay: 10-100 kPa, Silt: 5-20 kPa, Sand: 0-5 kPa, Gravel: 0 kPa.

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

Q3: Why use submerged unit weight?
A: Submerged unit weight accounts for buoyancy effects when soil is below the water table.

Q4: What does negative cohesion mean?
A: Negative values suggest calculation errors as cohesion can't be negative. Check your input values.

Q5: When should I adjust the tolerance?
A: Increase tolerance for preliminary estimates or when input data has high uncertainty.