Cohesion of Soil given Round Footing and Bearing Capacity Calculator

Cohesion of Soil Formula:

\[ C_r = \frac{q_f - (\sigma' \times N_q + 0.5 \times \gamma \times B \times N_\gamma \times 0.6)}{1.3 \times N_c} \]

Ultimate Bearing Capacity:

kPa

Effective Surcharge:

kPa

Bearing Capacity Factor (Surcharge):

Unit Weight of Soil:

kN/m³

Width of Footing:

Bearing Capacity Factor (Unit Weight):

Bearing Capacity Factor (Cohesion):

Cohesion of Soil: kPa

1. What is Cohesion of Soil given Round Footing?

Definition: This calculator determines the cohesion of soil beneath a round footing based on bearing capacity theory and soil parameters.

Purpose: It helps geotechnical engineers and foundation designers evaluate soil strength for round footing design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C_r = \frac{q_f - (\sigma' \times N_q + 0.5 \times \gamma \times B \times N_\gamma \times 0.6)}{1.3 \times N_c} \]

Where:

\( C_r \) — Cohesion of soil (kPa)
\( q_f \) — Ultimate bearing capacity (kPa)
\( \sigma' \) — Effective surcharge (kPa)
\( N_q \) — Bearing capacity factor for surcharge (±5%)
\( \gamma \) — Unit weight of soil (kN/m³)
\( B \) — Width of footing (m)
\( N_\gamma \) — Bearing capacity factor for unit weight (±5%)
\( N_c \) — Bearing capacity factor for cohesion (±5%)

Explanation: The formula calculates soil cohesion by considering the bearing capacity contributions from surcharge, soil weight, and footing geometry.

3. Importance of Soil Cohesion Calculation

Details: Accurate cohesion estimation is crucial for designing stable foundations, predicting soil behavior under load, and ensuring structural safety.

4. Using the Calculator

Tips: Enter all required parameters. Bearing capacity factors typically have ±5% uncertainty. Default values are provided for common soil types.

5. Frequently Asked Questions (FAQ)

Q1: What is typical cohesion value range?
A: Cohesion varies: 0-10 kPa for loose soils, 10-50 kPa for medium, 50-100 kPa for stiff clays.

Q2: Why 0.6 factor in the formula?
A: This accounts for the shape factor of round footings compared to strip footings.

Q3: How to determine bearing capacity factors?
A: They depend on soil friction angle - use tables from geotechnical references.

Q4: What if my soil has no cohesion?
A: For cohesionless soils (sand), enter 0 and rely on other bearing capacity components.

Q5: How accurate is this calculation?
A: It provides theoretical estimates - always verify with field tests for critical projects.