Bearing Capacity Factor Dependent on Cohesion for Circular Footing Calculator

Bearing Capacity Factor Formula:

\[ N_c = \frac{q_f - \sigma_s}{1.3 \times C} \]

Ultimate Bearing Capacity:

kPa

Effective Surcharge:

kPa

Cohesion in Soil:

kPa

Tolerance:

Bearing Capacity Factor (N_c):

1. What is Bearing Capacity Factor Dependent on Cohesion?

Definition: The bearing capacity factor (N_c) is a dimensionless coefficient that relates the ultimate bearing capacity of soil to its cohesion for circular footings.

Purpose: It helps geotechnical engineers determine the load-bearing capacity of cohesive soils for foundation design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ N_c = \frac{q_f - \sigma_s}{1.3 \times C} \]

Where:

\( N_c \) — Bearing capacity factor dependent on cohesion
\( q_f \) — Ultimate bearing capacity (kPa)
\( \sigma_s \) — Effective surcharge (kPa)
\( C \) — Cohesion of soil (kPa)

Explanation: The formula calculates the bearing capacity factor by accounting for the net bearing pressure (ultimate capacity minus surcharge) and the soil's cohesion.

3. Importance of Bearing Capacity Factor

Details: Accurate calculation of N_c is crucial for designing safe and economical foundations, especially in cohesive soils where bearing capacity is significantly influenced by soil cohesion.

4. Using the Calculator

Tips: Enter the ultimate bearing capacity, effective surcharge, soil cohesion, and tolerance percentage (default ±5%). All values must be ≥ 0 except cohesion which must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the factor 1.3 used in the formula?
A: The 1.3 factor accounts for the shape effect of circular footings compared to strip footings.

Q2: What is a typical range for N_c?
A: For cohesive soils, N_c typically ranges between 5 and 10, but can vary based on soil conditions.

Q3: What does the tolerance percentage represent?
A: The tolerance accounts for uncertainties in soil parameters and provides a safe range for design purposes.

Q4: How does surcharge affect the bearing capacity?
A: Higher surcharge reduces the net bearing capacity, thus decreasing the calculated N_c value.

Q5: When would I adjust the tolerance?
A: Increase tolerance for highly variable soil conditions or when using conservative estimates.