1. What is Angle of Internal Friction?

Definition: The angle of internal friction (φ) is a measure of a material's shear strength, calculated from its coefficient of internal friction (μ).

Purpose: It's crucial in geotechnical engineering for analyzing soil stability, slope failure, and bearing capacity calculations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \phi \) — Angle of internal friction (degrees)
• \( \mu \) — Coefficient of internal friction (dimensionless)

Explanation: The arctangent function converts the friction coefficient (ratio of shear to normal stress) into an angle representing the material's shear resistance.

3. Importance of Angle of Internal Friction

Details: This parameter is fundamental in designing earth-retaining structures, assessing slope stability, and determining soil bearing capacity.

4. Using the Calculator

Tips: Enter the coefficient of internal friction (typically between 0.2 and 1.0 for soils). The value must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical angle for sandy soil?
A: Loose sand: 28-34°, dense sand: 35-45° (μ ≈ 0.5-1.0).

Q2: How does this relate to the Mohr-Coulomb failure criterion?
A: φ is a key parameter in the Mohr-Coulomb equation: τ = c + σ·tan(φ).

Q3: What's the difference between internal and external friction?
A: Internal friction occurs within a material (soil grains), while external friction occurs between different materials.

Q4: Can the angle exceed 45°?
A: Yes, for very dense or angular materials, φ can reach 50° or more.

Q5: How is μ determined experimentally?
A: Through direct shear tests or triaxial compression tests on soil samples.