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

Formula Used:

\[ C = \frac{q_{nu} - \left( \sigma_s \times (N_q - 1) + 0.5 \times B \times \gamma \times N_\gamma \right)}{\frac{2}{3} \times N_c} \]

Net Ultimate BC (q_nu):

kPa

Effective Surcharge (σ_s):

kPa

Bearing Capacity Factor (N_q):

Width of Footing (B):

Unit Weight of Soil (γ):

kN/m³

Bearing Capacity Factor (N_γ):

Bearing Capacity Factor (N_c):

Cohesion in Soil (C):

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1. What is Cohesion of Soil?

Cohesion in Soil is the ability of like particles within soil to hold onto each other. It is the shear strength or force that binds together like particles in the structure of a soil. It's a crucial parameter in geotechnical engineering for determining soil stability.

2. How Does the Calculator Work?

The calculator uses the formula for local shear failure:

\[ C = \frac{q_{nu} - \left( \sigma_s \times (N_q - 1) + 0.5 \times B \times \gamma \times N_\gamma \right)}{\frac{2}{3} \times N_c} \]

Where:

\( C \) — Cohesion in Soil (kPa)
\( q_{nu} \) — Net Ultimate Bearing Capacity (kPa)
\( \sigma_s \) — Effective Surcharge (kPa)
\( N_q \) — Bearing Capacity Factor dependent on Surcharge
\( B \) — Width of Footing (m)
\( \gamma \) — Unit Weight of Soil (kN/m³)
\( N_\gamma \) — Bearing Capacity Factor dependent on Unit Weight
\( N_c \) — Bearing Capacity Factor dependent on Cohesion

Explanation: This formula calculates soil cohesion based on the net ultimate bearing capacity and other soil parameters for local shear failure conditions.

3. Importance of Cohesion Calculation

Details: Accurate cohesion calculation is essential for foundation design, slope stability analysis, and determining the shear strength of soil in geotechnical engineering projects.

4. Using the Calculator

Tips: Enter all required parameters in appropriate units. Ensure values are positive and bearing capacity factors are greater than zero for valid results.

5. Frequently Asked Questions (FAQ)

Q1: What is local shear failure?
A: Local shear failure occurs when the soil fails progressively beneath the foundation, with some soil still providing support, typically in medium-dense soils.

Q2: How does cohesion affect soil strength?
A: Cohesion significantly increases soil shear strength, particularly in cohesive soils like clays, where particles bond together.

Q3: What are typical cohesion values for different soil types?
A: Cohesion ranges from 0 kPa for clean sands to 10-100 kPa for clays, and can be higher for cemented soils.

Q4: When is this formula applicable?
A: This formula is specifically designed for calculating cohesion in cases of local shear failure in soil mechanics.

Q5: How accurate is this calculation?
A: The accuracy depends on the precision of input parameters. Laboratory testing may be required for critical applications.