Bearing Capacity Factor Dependent on Unit Weight for Square Footing Calculator

Bearing Capacity Factor Formula:

\[ N_γ = \frac{q_{fc} - (σ_s \times N_q)}{0.4 \times γ \times B} \]

Ultimate Bearing Capacity (q_fc):

Effective Surcharge (σ_s):

Bearing Capacity Factor (N_q):

Unit Weight of Soil (γ):

N/m³

Width of Footing (B):

Bearing Capacity Factor (N_γ):

1. What is Bearing Capacity Factor Dependent on Unit Weight?

Definition: This is a dimensionless factor that accounts for the contribution of soil's unit weight to the ultimate bearing capacity of a square footing.

Purpose: It helps geotechnical engineers determine the safe bearing capacity of soil for foundation design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ N_γ = \frac{q_{fc} - (σ_s \times N_q)}{0.4 \times γ \times B} \]

Where:

\( N_γ \) — Bearing capacity factor dependent on unit weight
\( q_{fc} \) — Ultimate bearing capacity in soil (Pa)
\( σ_s \) — Effective surcharge (Pa)
\( N_q \) — Bearing capacity factor dependent on surcharge (±5%)
\( γ \) — Unit weight of soil (N/m³)
\( B \) — Width of footing (m)

3. Importance of Bearing Capacity Factor

Details: Accurate calculation ensures foundation stability, prevents settlement issues, and optimizes foundation design.

4. Using the Calculator

Tips: Enter all required parameters. Default values are provided for reference. Ensure all values are positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for N_γ?
A: Values typically range from 0 to 50 depending on soil type and footing shape.

Q2: Why is N_q marked with ±5%?
A: This indicates the factor has an approximate accuracy of ±5% in most practical cases.

Q3: How does footing width affect the result?
A: Wider footings generally have higher bearing capacity factors due to deeper influence zones.

Q4: What units should be used?
A: Use consistent SI units (Pa for pressure, N/m³ for unit weight, meters for dimensions).

Q5: When would this calculation be invalid?
A: For very narrow footings (B < 0.3m) or in special soil conditions like organic soils.