Bearing Capacity Factor Dependent on Cohesion for Rectangular Footing Calculator

Bearing Capacity Factor Formula:

\[ N_c = \frac{q_{fc} - (\sigma_s \times N_q + 0.4 \times \gamma \times B \times N_\gamma)}{C \times (1 + 0.3 \times \frac{B}{L})} \]

Ultimate Bearing Capacity (q_fc):

kPa

Effective Surcharge (σ_s):

kPa

Bearing Capacity Factor (N_q):

Unit Weight of Soil (γ):

N/m³

Width of Footing (B):

Bearing Capacity Factor (N_γ):

Cohesion in Soil (C):

kPa

Length of Footing (L):

Bearing Capacity Factor (N_c):

1. What is Bearing Capacity Factor Dependent on Cohesion?

Definition: This calculator determines the bearing capacity factor (N_c) for rectangular footings based on soil properties and footing dimensions.

Purpose: It helps geotechnical engineers and foundation designers calculate the bearing capacity factor needed for foundation design calculations.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ N_c = \frac{q_{fc} - (\sigma_s \times N_q + 0.4 \times \gamma \times B \times N_\gamma)}{C \times (1 + 0.3 \times \frac{B}{L})} \]

Where:

\( N_c \) — Bearing capacity factor dependent on cohesion
\( q_{fc} \) — Ultimate bearing capacity in soil (kPa)
\( \sigma_s \) — Effective surcharge (kPa)
\( N_q \) — Bearing capacity factor dependent on surcharge (±5%)
\( \gamma \) — Unit weight of soil (N/m³)
\( B \) — Width of footing (m)
\( N_\gamma \) — Bearing capacity factor dependent on unit weight (±5%)
\( C \) — Cohesion in soil (kPa)
\( L \) — Length of footing (m)

3. Importance of Bearing Capacity Factor Calculation

Details: Accurate calculation of N_c is crucial for designing safe and economical foundations that can support structural loads without excessive settlement.

4. Using the Calculator

Tips: Enter all required parameters. Note that bearing capacity factors N_q and N_γ typically have ±5% variability.

5. Frequently Asked Questions (FAQ)

Q1: Why is the bearing capacity factor important?
A: It quantifies the contribution of soil cohesion to the overall bearing capacity of the foundation.

Q2: What's the typical range for N_c?
A: For cohesive soils, N_c typically ranges between 5 and 37 depending on soil conditions and footing shape.

Q3: How does footing shape affect N_c?
A: The term (1 + 0.3 × B/L) accounts for rectangular footing shape effects.

Q4: What if my footing is square?
A: For square footings (B = L), the shape factor becomes 1.3.

Q5: How accurate is this calculation?
A: The calculation provides a theoretical value; actual field conditions may vary due to soil heterogeneity.