1. What is Ultimate Bearing Capacity?

Definition: Ultimate Bearing Capacity of Soil is the minimum gross pressure intensity at the base of the foundation at which the soil fails in shear.

Purpose: It helps geotechnical engineers determine the maximum load that can be applied to soil without risking shear failure.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( q_{fc} \) — Ultimate Bearing Capacity (kPa)
• \( q_{nsa}' \) — Net Safe Bearing Capacity (kPa)
• \( FOS \) — Factor of Safety (typically 2.5-3.0)
• \( \sigma_s \) — Effective Surcharge (kPa)

Explanation: The net safe bearing capacity is multiplied by the safety factor and then added to the effective surcharge to get the ultimate capacity.

3. Importance of Bearing Capacity Calculation

Details: Proper bearing capacity estimation ensures foundation stability, prevents structural failure, and optimizes foundation design.

4. Using the Calculator

Tips: Enter the net safe bearing capacity (±5%), factor of safety (±5%), and effective surcharge (kPa ±5%). All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical Factor of Safety for foundations?
A: Typically 2.5-3.0 for buildings, but may vary based on soil conditions and importance of structure.

Q2: How is Net Safe Bearing Capacity determined?
A: Through soil testing, laboratory analysis, and empirical correlations with soil properties.

Q3: What does Effective Surcharge represent?
A: It accounts for additional vertical pressure from adjacent structures or soil layers above foundation level.

Q4: Why the ±5% tolerance on inputs?
A: Soil properties naturally vary, and this accounts for typical measurement uncertainties.

Q5: When would I need to calculate ultimate bearing capacity?
A: For foundation design of buildings, bridges, retaining walls, and other structures.

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