1. What is the Active Pressure Coefficient?

The Active Pressure Coefficient (Ka) is a dimensionless parameter used in geotechnical engineering to calculate the lateral earth pressure exerted by soil or water on a retaining structure when the wall moves away from the soil.

2. How Does the Calculator Work?

The calculator uses the Active Pressure Coefficient equation for water:

Where:

• \( \phi \) — Angle of internal friction (degrees)

Explanation: The equation relates the angle of internal friction to the active earth pressure coefficient for water-bearing soils.

3. Importance of Ka Calculation

Details: Accurate Ka calculation is crucial for designing retaining walls, sheet piles, and other earth-retaining structures to ensure stability against water pressure.

4. Using the Calculator

Tips: Enter the angle of internal friction in degrees (0-90°). The value must be valid (between 0 and 90).

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for Ka values?
A: For most soils, Ka ranges between 0.2 and 0.5, depending on the angle of internal friction.

Q2: How does water affect the active pressure?
A: Water increases the total pressure and reduces the effective stress in the soil, which must be considered in the design.

Q3: What's the difference between Ka, Kp, and K0?
A: Ka is for active pressure (wall moving away), Kp for passive pressure (wall moving into soil), and K0 for at-rest pressure (no wall movement).

Q4: Can this be used for cohesive soils?
A: This equation is for cohesionless soils. For cohesive soils, additional terms accounting for cohesion are needed.

Q5: How does soil saturation affect Ka?
A: Saturated soils have reduced effective stress and thus different pressure distribution, requiring separate analysis.