Effective Cohesion given Factor of Safety in Absence of Flow Net Calculator

Effective Cohesion Formula:

\[ c' = \frac{(fs \times \Sigma T) - (\Sigma N \times \tan(\phi' \times \frac{\pi}{180}))}{L'} \]

Factor of Safety:

Sum of all Tangential Component:

Sum of all Normal Component:

Effective Angle of Internal Friction:

Length of Slip Arc:

Effective Cohesion (Pascal):

1. What is Effective Cohesion given Factor of Safety?

Definition: This calculator determines the effective cohesion of soil when the factor of safety is known in the absence of a flow net.

Purpose: It helps geotechnical engineers assess soil stability and design appropriate foundations or slopes.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ c' = \frac{(fs \times \Sigma T) - (\Sigma N \times \tan(\phi' \times \frac{\pi}{180}))}{L'} \]

Where:

\( c' \) — Effective cohesion (Pascal)
\( fs \) — Factor of Safety
\( \Sigma T \) — Sum of all tangential components (N)
\( \Sigma N \) — Sum of all normal components (N)
\( \phi' \) — Effective angle of internal friction (degrees)
\( L' \) — Length of slip arc (m)

Explanation: The formula calculates the soil's cohesive strength by considering the balance between resisting and driving forces along a potential slip surface.

3. Importance of Effective Cohesion Calculation

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

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. The calculator accounts for a ±5% variation in input values.

5. Frequently Asked Questions (FAQ)

Q1: What is effective cohesion?
A: It's the soil's cohesive strength attributed to its inherent properties like chemical bonding between particles.

Q2: Why ±5% variation?
A: This accounts for typical measurement uncertainties in geotechnical parameters.

Q3: When would I use this calculation?
A: For slope stability analysis when a flow net isn't available but factor of safety is known.

Q4: What's a typical factor of safety?
A: Usually 1.3-1.5 for slopes, but depends on project requirements and consequences of failure.

Q5: How do I measure tangential and normal components?
A: These are typically determined from slope stability analysis or laboratory shear tests.