Active Earth Pressure Calculator Formula

Active Earth Pressure Formula:

\[ P_a = K_a \times \gamma \times H^2 / 2 \]

Active Earth Pressure (P_a):

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1. What is Active Earth Pressure?

Active earth pressure is the lateral pressure exerted by soil on a retaining structure when the soil is allowed to move away from the structure. It represents the minimum pressure that soil can exert on a retaining wall.

2. How Does the Calculator Work?

The calculator uses the active earth pressure formula:

\[ P_a = K_a \times \gamma \times H^2 / 2 \]

Where:

\( P_a \) — Active earth pressure (kN/m)
\( K_a \) — Active earth pressure coefficient (dimensionless)
\( \gamma \) — Soil density (kN/m³)
\( H \) — Height of the retaining wall (m)

Explanation: The formula calculates the total lateral force per unit length of the retaining wall caused by the soil in active state.

3. Importance of Active Earth Pressure Calculation

Details: Accurate calculation of active earth pressure is crucial for designing safe and efficient retaining structures, preventing wall failures, and ensuring structural stability in geotechnical engineering projects.

4. Using the Calculator

Tips: Enter the active coefficient (K_a), soil density in kN/m³, and wall height in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How is the active coefficient (K_a) determined?
A: K_a is calculated using the formula: K_a = (1 - sinφ)/(1 + sinφ), where φ is the soil's angle of internal friction.

Q2: What's the difference between active and passive earth pressure?
A: Active pressure occurs when soil moves away from the wall (minimum pressure), while passive pressure occurs when soil is pushed against the wall (maximum pressure).

Q3: Does this formula account for water pressure?
A: No, this formula is for dry soil only. For submerged conditions, additional calculations for water pressure are needed.

Q4: What are typical values for soil density?
A: Typical values range from 16-22 kN/m³ for most soils, with sand around 18-20 kN/m³ and clay around 16-20 kN/m³.

Q5: When is this formula not applicable?
A: This formula may not be accurate for cohesive soils, stratified soils, or cases with surcharge loads without appropriate modifications.