Cohesion of Soil given Bearing Capacity for Square Footing Calculator

Cohesion Formula:

\[ C = \frac{q_f - \sigma_s}{N_c \times (1 + 0.3 \times \frac{B}{L})} \]

Ultimate Bearing Capacity:

kPa

Effective Surcharge:

kPa

Bearing Capacity Factor:

Width of Footing:

Length of Footing:

Tolerance:

Cohesion of Soil (kPa):

1. What is Cohesion of Soil Calculator?

Definition: This calculator determines the cohesion of soil based on bearing capacity measurements for square footings.

Purpose: It helps geotechnical engineers and construction professionals evaluate soil strength parameters for foundation design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C = \frac{q_f - \sigma_s}{N_c \times (1 + 0.3 \times \frac{B}{L})} \]

Where:

\( C \) — Cohesion of soil (kPa)
\( q_f \) — Ultimate bearing capacity (kPa)
\( \sigma_s \) — Effective surcharge (kPa)
\( N_c \) — Bearing capacity factor (typically 9 for square footings)
\( B \) — Width of footing (m)
\( L \) — Length of footing (m)

Explanation: The formula accounts for the footing dimensions and the bearing capacity factor to back-calculate soil cohesion.

3. Importance of Soil Cohesion Calculation

Details: Soil cohesion is critical for determining foundation stability, slope stability, and earthwork design.

4. Using the Calculator

Tips: Enter all required parameters including ultimate bearing capacity, surcharge, bearing capacity factor (default 9), footing dimensions, and tolerance (default ±5%).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical bearing capacity factor for square footings?
A: The value is typically 9 for square footings in cohesive soils.

Q2: How do I determine ultimate bearing capacity?
A: This is typically obtained from plate load tests or estimated from soil properties.

Q3: What does the tolerance percentage represent?
A: It provides a range of acceptable values (±%) around the calculated cohesion to account for measurement uncertainties.

Q4: When would effective surcharge be zero?
A: When there's no additional load at the ground surface adjacent to the footing.

Q5: How does footing shape affect the calculation?
A: The formula includes a shape factor (0.3) that accounts for rectangular footings. For perfectly square footings (B/L=1), this becomes 1.3.