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Cohesion Of Soil Given Net Ultimate Bearing Capacity For General Shear Failure Calculator

Formula Used:

\[ C = \frac{q_{nu} - \left( \sigma_s \times (N_q - 1) + 0.5 \times B \times \gamma \times N_\gamma \right)}{N_c} \]

kPa
kPa
m
N/m³

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1. What is the Cohesion Calculation Formula?

The formula calculates soil cohesion from net ultimate bearing capacity, effective surcharge, and bearing capacity factors. It's derived from Terzaghi's bearing capacity theory for general shear failure conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ C = \frac{q_{nu} - \left( \sigma_s \times (N_q - 1) + 0.5 \times B \times \gamma \times N_\gamma \right)}{N_c} \]

Where:

Explanation: This formula isolates the cohesion component from the complete bearing capacity equation, allowing determination of soil cohesion when other parameters are known.

3. Importance of Cohesion Calculation

Details: Accurate cohesion determination is crucial for foundation design, slope stability analysis, and earth retaining structures. Cohesion represents the soil's inherent shear strength from particle bonding.

4. Using the Calculator

Tips: Enter all values in consistent units (kPa for pressures, m for length, N/m³ for unit weight). Ensure bearing capacity factors are appropriate for your soil type and failure mode.

5. Frequently Asked Questions (FAQ)

Q1: When is this formula applicable?
A: This formula applies to general shear failure conditions in cohesive soils where the complete bearing capacity equation is valid.

Q2: What are typical cohesion values for different soils?
A: Clay soils: 10-200 kPa, Silty soils: 5-50 kPa, Sandy soils: 0-10 kPa (often negligible).

Q3: How do I determine bearing capacity factors?
A: Bearing capacity factors depend on soil friction angle and can be found in geotechnical engineering tables or calculated using established formulas.

Q4: What if I get negative cohesion?
A: Negative cohesion indicates input error or inappropriate application. Cohesion should always be positive or zero for cohesionless soils.

Q5: Can this be used for all soil types?
A: Primarily for cohesive soils. For cohesionless soils, cohesion is typically zero and different approaches are used.

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