Bearing Capacity Factor Dependent on Surcharge given Angle of Shearing Resistance Calculator

Bearing Capacity Factor Formula:

\[ N_q = \frac{N_c}{\cot(\phi)} + 1 \]

Bearing Capacity Factor dependent on Surcharge (Nq):

1. What is Bearing Capacity Factor Dependent on Surcharge?

Definition: Nq is a dimensionless factor used in geotechnical engineering to calculate the bearing capacity of shallow foundations considering the surcharge effect.

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

2. How Does the Calculator Work?

The calculator uses the formula:

\[ N_q = \frac{N_c}{\cot(\phi)} + 1 \]

Where:

\( N_q \) — Bearing capacity factor dependent on surcharge
\( N_c \) — Bearing capacity factor dependent on cohesion
\( \phi \) — Angle of shearing resistance (degrees)

Explanation: The formula relates Nq to Nc and the soil's angle of internal friction (φ), accounting for the surcharge effect on bearing capacity.

3. Importance of Nq Calculation

Details: Accurate Nq values are essential for safe foundation design, preventing excessive settlement or bearing capacity failure.

4. Using the Calculator

Tips:

Enter Nc (typically 5.14 for cohesive soils)
Enter φ (angle of shearing resistance) in degrees (0° < φ < 90°)
Specify tolerance percentage (default ±5%)

5. Frequently Asked Questions (FAQ)

Q1: What is a typical Nc value?
A: For purely cohesive soils (φ=0), Nc is typically 5.14. For other soils, it depends on φ and the failure mechanism.

Q2: How does φ affect Nq?
A: Nq increases exponentially with increasing φ, showing greater bearing capacity for granular soils.

Q3: Why include a tolerance factor?
A: Soil properties are variable - tolerance accounts for uncertainty in φ and Nc measurements.

Q4: What's the range for φ?
A: φ typically ranges from 0° (pure clay) to 45° (dense gravel), though values up to 50° are possible.

Q5: How is this used in foundation design?
A: Nq is used in the bearing capacity equation: q_ult = cNc + qNq + 0.5γBNγ