Angle of Internal Friction Formula:
Definition: The angle of internal friction is a measure of the shear strength of soils due to friction between particles.
Purpose: It's a key parameter in soil mechanics used to analyze slope stability, bearing capacity, and earth pressure.
The calculator uses the formula:
Where:
Explanation: The angle is calculated as the arctangent of the ratio of shear strength to normal stress.
Details: This parameter is crucial for designing foundations, retaining walls, and assessing slope stability in cohesionless soils.
Tips: Enter the shear strength and normal stress values in MPa. The ±5% indicates typical measurement accuracy.
Q1: What's a typical range for φ in cohesionless soils?
A: For sands: 28°-45°; for gravels: 35°-50°; higher values indicate more angular particles.
Q2: Why is this only for cohesionless soils?
A: Cohesive soils have additional shear strength from cohesion, requiring a different formula (Mohr-Coulomb).
Q3: How is shear strength determined experimentally?
A: Typically through direct shear tests or triaxial tests in a geotechnical laboratory.
Q4: What affects the angle of internal friction?
A: Particle shape, size distribution, density, and mineral composition all influence φ.
Q5: How accurate is this calculation?
A: The ±5% reflects typical measurement accuracy; actual field conditions may vary further.