Cohesion of Soil given Angle of Inclination and Slope angle Calculator

Effective Cohesion Formula:

\[ C_{eff} = \left(F_s - \frac{\tan(\phi)}{\tan(\theta)}\right) \times \left(\frac{1}{2} \gamma H \frac{\sin(i-\theta)}{\sin i} \sin \theta\right) \]

Factor of Safety (F_s):

Angle of Internal Friction (φ):

Slope Angle (θ):

Unit Weight of Soil (γ):

kN/m³

Height of Wedge (H):

Inclination Angle (i):

Effective Cohesion (kPa):

1. What is Effective Cohesion Calculator?

Definition: This calculator determines the effective cohesion of soil based on slope stability analysis considering the angle of inclination and slope angle.

Purpose: It helps geotechnical engineers assess soil stability and design appropriate slope protection measures.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C_{eff} = \left(F_s - \frac{\tan(\phi)}{\tan(\theta)}\right) \times \left(\frac{1}{2} \gamma H \frac{\sin(i-\theta)}{\sin i} \sin \theta\right) \]

Where:

\( C_{eff} \) — Effective cohesion (kPa)
\( F_s \) — Factor of safety
\( \phi \) — Angle of internal friction (°)
\( \theta \) — Slope angle (°)
\( \gamma \) — Unit weight of soil (kN/m³)
\( H \) — Height of wedge (m)
\( i \) — Angle of inclination to horizontal (°)

Explanation: The formula calculates the shear strength required to maintain slope stability considering various geometric and material properties.

3. Importance of Effective Cohesion Calculation

Details: Proper cohesion estimation is crucial for slope stability analysis, foundation design, and preventing landslides or soil failures.

4. Using the Calculator

Tips: Enter all required parameters. Default values are provided for typical conditions. All angles must be between 0° and 90°.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical factor of safety for slopes?
A: Common values range from 1.3 to 2.0 depending on consequences of failure and confidence in parameters.

Q2: How does internal friction angle affect cohesion?
A: Higher friction angles typically require less cohesion for the same factor of safety.

Q3: What units should I use for input?
A: Angles in degrees, height in meters, unit weight in kN/m³. The output is in kPa.

Q4: What does ±5% mean for inputs?
A: It indicates the typical measurement or estimation uncertainty for each parameter.

Q5: When would this calculation be used?
A: For slope stability analysis, retaining wall design, and excavation support systems.