Bearing Capacity Factor Dependent on Unit Weight for Strip Footing Calculator

Bearing Capacity Factor Formula:

\[ N_γ = \frac{q_{fc} - (σ_s \times N_q)}{0.5 \times γ \times B} \]

Ultimate Bearing Capacity (q_fc):

kPa

Effective Surcharge (σ_s):

kPa

Bearing Capacity Factor (N_q):

Unit Weight of Soil (γ):

kN/m³

Width of Footing (B):

Bearing Capacity Factor (N_γ):

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

Definition: This factor (N_γ) is a dimensionless parameter used in geotechnical engineering to calculate the ultimate bearing capacity of shallow foundations.

Purpose: It accounts for the contribution of soil's unit weight to the bearing capacity of strip footings.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ N_γ = \frac{q_{fc} - (σ_s \times N_q)}{0.5 \times γ \times B} \]

Where:

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

3. Importance of Bearing Capacity Factor

Details: Accurate calculation of N_γ is crucial for designing stable foundations that can support structural loads without shear failure.

4. Using the Calculator

Tips: Enter all required parameters. Note that N_q has a ±5% tolerance to account for typical variations in soil conditions.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical range for N_γ?
A: For most soils, N_γ ranges between 0 and 50, depending on soil type and friction angle.

Q2: Why is there a ±5% tolerance on N_q?
A: This accounts for natural variability in soil properties and measurement uncertainties.

Q3: How does footing width affect N_γ?
A: Wider footings generally have higher bearing capacity, which is reflected in the inverse relationship with N_γ.

Q4: What if my N_γ calculation is negative?
A: This indicates an error in input values, as N_γ should always be positive. Check your q_fc and σ_s values.

Q5: How accurate is this calculation?
A: While theoretically sound, actual field conditions may vary. Always consult a geotechnical engineer for critical applications.