Retaining Wall Calculation Tool

Retaining Wall Stability Calculations:

\[ FOS = \frac{\text{Resisting Moments}}{\text{Overturning Moments}} \] \[ FOS_{sliding} = \frac{\mu \times W}{P_a} \]

Wall Height:

meters

Wall Width:

meters

Soil Unit Weight:

kN/m³

Soil Friction Angle:

degrees

Wall Type:

Active Earth Pressure (Pa):

Factor of Safety (Overturning):

Factor of Safety (Sliding):

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1. What is a Retaining Wall Calculation?

Retaining wall calculations determine the stability of a wall against overturning and sliding. These calculations ensure the wall can withstand the lateral earth pressures from the soil it retains.

2. How Does the Calculator Work?

The calculator uses standard geotechnical engineering formulas:

\[ FOS_{overturning} = \frac{\text{Resisting Moments}}{\text{Overturning Moments}} \] \[ FOS_{sliding} = \frac{\mu \times W}{P_a} \] \[ P_a = \frac{1}{2} K_a \gamma H^2 \] \[ K_a = \tan^2(45^\circ - \phi/2) \]

Where:

\( FOS \) — Factor of Safety
\( P_a \) — Active earth pressure (kN/m)
\( K_a \) — Active earth pressure coefficient
\( \gamma \) — Soil unit weight (kN/m³)
\( H \) — Wall height (m)
\( \phi \) — Soil friction angle (degrees)
\( \mu \) — Coefficient of friction (0.6 for concrete-soil)
\( W \) — Wall weight (kN)

Explanation: The calculations verify that the wall has sufficient weight and base width to resist the soil pressures.

3. Importance of Wall Stability Analysis

Details: Proper stability analysis prevents wall failures that could lead to property damage or injuries. Minimum factors of safety are typically 1.5 for overturning and 1.5 for sliding.

4. Using the Calculator

Tips: Enter wall dimensions, soil properties, and select wall type. The calculator assumes concrete density of 24 kN/m³ and friction coefficient of 0.6.

5. Frequently Asked Questions (FAQ)

Q1: What is the minimum required factor of safety?
A: Typically 1.5 for both overturning and sliding, though local codes may vary.

Q2: How does wall type affect the calculations?
A: Gravity walls rely on their mass, while cantilever walls use their shape and reinforcement to resist pressures.

Q3: What if my soil has cohesion?
A: This calculator is for cohesionless soils only. Cohesive soils require more complex analysis.

Q4: How accurate are these calculations?
A: They provide preliminary estimates. Final designs should be verified by a geotechnical engineer.

Q5: What about water pressure or surcharge loads?
A: This calculator doesn't account for these factors which require additional analysis.