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Friction Angle Formula:
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The friction angle (φ) is a fundamental soil mechanics parameter that represents the shear strength of soil. It's the angle at which soil fails under shear stress and is a key parameter in geotechnical engineering for slope stability, foundation design, and earth pressure calculations.
The calculator uses the friction angle formula:
Where:
Explanation: The formula calculates the angle whose tangent is the ratio of shear stress to effective normal stress, representing the internal friction of the soil material.
Details: Accurate friction angle determination is crucial for designing stable slopes, calculating bearing capacity of foundations, designing retaining structures, and assessing landslide risks in geotechnical engineering projects.
Tips: Enter shear stress and effective normal stress in Pascals (Pa). Both values must be positive numbers. The calculator will compute the friction angle in degrees.
Q1: What is the typical range of friction angles for different soils?
A: Friction angles vary: clean sand (28-45°), silty sand (27-34°), clay (0-30°), with cohesive soils having both friction and cohesion components.
Q2: How is friction angle determined experimentally?
A: Through direct shear tests, triaxial compression tests, or cone penetration tests in laboratory or field conditions.
Q3: What affects the friction angle of soil?
A: Particle size distribution, mineral composition, density, moisture content, and stress history significantly influence the friction angle.
Q4: What's the difference between peak and residual friction angle?
A: Peak friction angle occurs at maximum shear strength, while residual friction angle is the lower value after significant shear displacement.
Q5: How does drainage condition affect friction angle measurement?
A: Drained conditions measure effective stress parameters (φ'), while undrained conditions measure total stress parameters, crucial for different loading scenarios.