1. What is Ultimate Bearing Capacity for Circular Footing?

Definition: The ultimate bearing capacity is the minimum gross pressure intensity at the base of the foundation at which the soil fails in shear.

Purpose: This calculation helps engineers determine the maximum load a circular footing can support before soil failure occurs.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( qf \) — Ultimate bearing capacity (kPa)
• \( C \) — Cohesion in soil (kPa)
• \( \sigma s \) — Effective surcharge (kPa)

Explanation: The formula combines the soil's cohesive strength with the additional load from surcharge to determine the total bearing capacity.

3. Importance of Bearing Capacity Calculation

Details: Proper bearing capacity estimation ensures foundation stability, prevents settlement issues, and guarantees structural safety.

4. Using the Calculator

Tips: Enter the soil cohesion in kPa, effective surcharge in kPa, and tolerance percentage (default 5%). All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the 7.4 factor in the formula?
A: This is the bearing capacity factor (Nc) for circular footings, derived from soil mechanics theory.

Q2: How is effective surcharge determined?
A: Effective surcharge is the vertical pressure from any additional load acting over the ground surface beyond basic earth pressure.

Q3: Why include a tolerance percentage?
A: The tolerance accounts for variations in soil properties and provides a safety margin in design calculations.

Q4: Can this be used for other footing shapes?
A: No, this formula is specific to circular footings. Other shapes require different bearing capacity factors.

Q5: What's a typical cohesion value for soils?
A: Cohesion varies widely: clay might be 10-100 kPa, while sand typically has 0-5 kPa cohesion.

Bearing Capacity Calculator© - All Rights Reserved 2025