Cohesion of Soil given Net Ultimate Bearing Capacity Calculator

Cohesion of Soil Formula:

\[ C_s = \frac{q_{nf} - (\sigma_s \times (N_q - 1) + 0.5 \times \gamma \times B \times N_\gamma)}{N_c} \]

Net 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 Net Ultimate Bearing Capacity?

Definition: This calculator determines the cohesion of soil based on net ultimate bearing capacity and other soil parameters.

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

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C_s = \frac{q_{nf} - (\sigma_s \times (N_q - 1) + 0.5 \times \gamma \times B \times N_\gamma)}{N_c} \]

Where:

\( C_s \) — Cohesion of Soil (kPa)
\( q_{nf} \) — Net Ultimate Bearing Capacity (kPa)
\( \sigma_s \) — Effective Surcharge (kPa)
\( N_q \) — Bearing Capacity Factor (Surcharge)
\( \gamma \) — Unit Weight of Soil (kN/m³)
\( B \) — Width of Footing (m)
\( N_\gamma \) — Bearing Capacity Factor (Unit Weight)
\( N_c \) — Bearing Capacity Factor (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. Bearing capacity factors typically have ±5% uncertainty. All values must be ≥ 0 except bearing capacity factors which must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is typical cohesion value for different soils?
A: Clay: 10-100 kPa, Silt: 5-20 kPa, Sand: 0-5 kPa, Gravel: 0 kPa.

Q2: How to determine bearing capacity factors?
A: They depend on soil friction angle - use standard geotechnical tables or equations.

Q3: What if I get negative cohesion?
A: Check your inputs - negative cohesion suggests calculation error or very loose soil.

Q4: How does surcharge affect cohesion calculation?
A: Higher surcharge reduces the apparent cohesion needed to achieve bearing capacity.

Q5: When would I use this calculation?
A: For shallow foundation design, retaining wall design, or slope stability analysis.