1. What is the Stability Factor?

The Stability Factor is a critical measure in retaining wall design that compares the resisting forces (which prevent movement) to the driving forces (which cause movement). A factor greater than 1 indicates a stable wall.

2. How Does the Calculator Work?

The calculator uses the Stability Factor formula:

Where:

• Resisting Forces — Sum of all forces preventing wall movement (lb)
• Driving Forces — Sum of all forces causing wall movement (lb)

Explanation: The equation provides a ratio that indicates whether the retaining wall is stable (SF > 1.5 typically) or at risk of failure.

3. Importance of Stability Factor

Details: Proper calculation of stability factor is essential for safe retaining wall design, preventing overturning, sliding, or bearing capacity failures.

4. Using the Calculator

Tips: Enter resisting and driving forces in pounds (lb). Both values must be positive numbers. Typical resisting forces include wall weight, soil friction, and passive pressure.

5. Frequently Asked Questions (FAQ)

Q1: What is a good stability factor value?
A: Generally, a factor of 1.5 or greater is considered safe for most retaining walls.

Q2: What are common resisting forces?
A: These include the weight of the wall, soil friction on the base, passive soil pressure, and any anchoring systems.

Q3: What are common driving forces?
A: These typically include lateral earth pressure from retained soil, hydrostatic pressure, and any surcharge loads.

Q4: Does this account for seismic forces?
A: No, special seismic analysis is needed in earthquake-prone areas as it introduces additional driving forces.

Q5: How does wall material affect stability?
A: Heavier materials (like concrete) increase resisting forces through greater weight, while friction characteristics affect sliding resistance.