Depth of Footing given Value of Bearing Capacity Factor Calculator

Depth of Footing Formula:

\[ D = \frac{qf - (Cs \times 5.7)}{\gamma} \]

Ultimate Bearing Capacity:

Cohesion of Soil:

Unit Weight of Soil:

N/m³

Tolerance:

Depth of Footing (m):

1. What is Depth of Footing given Value of Bearing Capacity Factor?

Definition: This calculator determines the required depth of a footing based on soil bearing capacity, cohesion, and unit weight, with optional tolerance percentage.

Purpose: It helps civil engineers and construction professionals design proper foundation depths for structural stability.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ D = \frac{qf - (Cs \times 5.7)}{\gamma} \]

Where:

\( D \) — Depth of Footing (meters)
\( qf \) — Ultimate Bearing Capacity (Pascals)
\( Cs \) — Cohesion of Soil (Pascals)
\( \gamma \) — Unit Weight of Soil (N/m³)
5.7 — Bearing Capacity Factor for cohesion

Explanation: The formula calculates the minimum depth required for a footing to safely distribute structural loads to the soil.

3. Importance of Footing Depth Calculation

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

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is the bearing capacity factor 5.7?
A: It's a theoretical value derived from soil mechanics that relates cohesion to bearing capacity in Terzaghi's bearing capacity theory.

Q2: When would soil cohesion be zero?
A: Cohesion is zero for non-cohesive soils like clean sand or gravel.

Q3: What's a typical unit weight for soil?
A: Typically 16-22 kN/m³ (16000-22000 N/m³) for most soils, but varies with moisture content and soil type.

Q4: Why include a tolerance percentage?
A: It accounts for safety factors, material variations, and construction tolerances in real-world applications.

Q5: How does depth affect bearing capacity?
A: Generally, deeper footings have higher bearing capacity due to increased overburden pressure and soil confinement.