Depth of Footing given Bearing Capacity for Purely Cohesive Soil Calculator

Depth of Footing Formula:

\[ D = \frac{qf - (Cs \times Nc)}{\gamma \times Nq} \]

Ultimate Bearing Capacity:

Cohesion of Soil:

Bearing Capacity Factor (Cohesion):

Unit Weight of Soil:

Bearing Capacity Factor (Surcharge):

Depth of Footing (m):

1. What is Depth of Footing given Bearing Capacity for Purely Cohesive Soil?

Definition: This calculator determines the required depth of a footing based on soil bearing capacity for purely cohesive soils.

Purpose: It helps civil engineers and construction professionals design appropriate foundation depths for structures on cohesive soils.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ D = \frac{qf - (Cs \times Nc)}{\gamma \times Nq} \]

Where:

\( D \) — Depth of Footing (meters)
\( qf \) — Ultimate Bearing Capacity (Pascal)
\( Cs \) — Cohesion of Soil (Pascal)
\( Nc \) — Bearing Capacity Factor dependent on Cohesion
\( \gamma \) — Unit Weight of Soil (N/m³)
\( Nq \) — Bearing Capacity Factor dependent on Surcharge

Explanation: The formula calculates the depth needed to achieve the required bearing capacity considering soil cohesion and unit weight.

3. Importance of Footing Depth Calculation

Details: Proper footing depth ensures structural stability, prevents settlement, and accounts for soil bearing capacity.

4. Using the Calculator

Tips: Enter all required values with appropriate units. Default values are provided for typical conditions. All values must be > 0 except cohesion which can be 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a purely cohesive soil?
A: A soil that derives its shear strength primarily from cohesion (like clay) rather than internal friction.

Q2: How accurate are these calculations?
A: Results are theoretical estimates; actual field conditions may vary by ±5% or more.

Q3: What are typical values for Nc and Nq?
A: For cohesive soils, Nc is typically 5.14-9, and Nq is typically 1-2.01.

Q4: How does unit weight affect footing depth?
A: Higher unit weight soils generally require shallower footings for the same bearing capacity.

Q5: When would I use this calculation?
A: When designing foundations for structures on clayey soils where cohesion is the primary strength factor.