1. What is Resisting Force from Coulomb's Equation?

Definition: This calculator determines the resisting force against sliding or failure using Coulomb's equation, which considers cohesion, normal force, and internal friction.

Purpose: It helps geotechnical engineers and civil engineers analyze slope stability and foundation bearing capacity.

2. How Does the Calculator Work?

The calculator uses Coulomb's equation:

Where:

• \( F_r \) — Resisting force (N)
• \( c_u \) — Unit cohesion (Pa)
• \( \Delta L \) — Curve length (m)
• \( N \) — Normal component of force (N)
• \( \phi \) — Angle of internal friction (degrees)

Explanation: The resisting force is the sum of cohesive forces along the failure surface and frictional forces normal to that surface.

3. Importance of Resisting Force Calculation

Details: Proper calculation of resisting force is crucial for assessing slope stability, designing retaining walls, and ensuring foundation safety.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. The tolerance field (default ±5%) helps account for material variability and measurement uncertainties.

5. Frequently Asked Questions (FAQ)

Q1: What is unit cohesion?
A: Unit cohesion is the shear strength of soil due to chemical bonding between particles, independent of normal stress.

Q2: How is angle of internal friction determined?
A: It's typically measured through triaxial or direct shear tests and represents the soil's frictional resistance.

Q3: Why include a tolerance percentage?
A: Soil properties can vary spatially, so the tolerance provides a realistic range of expected values.

Q4: What's a typical angle of internal friction?
A: For sand: 30-40°, for clay: 10-20°, but this varies with soil type and moisture content.

Q5: When would the normal component be zero?
A: In purely cohesive soils (φ=0), the frictional component disappears, and resistance comes only from cohesion.

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