Unit Weight of Soil given Bearing Capacity for Local Shear Failure Calculator

Unit Weight of Soil Formula:

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

Ultimate Bearing Capacity (q_fc):

kPa

Cohesion (C):

kPa

Bearing Capacity Factor (N_c):

Effective Surcharge (σ_s):

kPa

Bearing Capacity Factor (N_q):

Bearing Capacity Factor (N_γ):

Width of Footing (B):

Unit Weight of Soil (γ):

1. What is Unit Weight of Soil given Bearing Capacity for Local Shear Failure?

Definition: This calculator determines the unit weight of soil based on the bearing capacity equation for local shear failure conditions.

Purpose: It helps geotechnical engineers and construction professionals evaluate soil properties when designing foundations.

2. How Does the Calculator Work?

The calculator uses the formula:

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

Where:

\( \gamma \) — Unit weight of soil (kN/m³)
\( q_{fc} \) — Ultimate bearing capacity (kPa)
\( C \) — Cohesion of soil (kPa)
\( N_c, N_q, N_\gamma \) — Bearing capacity factors
\( \sigma_s \) — Effective surcharge (kPa)
\( B \) — Width of footing (m)

Explanation: The formula calculates the unit weight by considering the bearing capacity components from cohesion, surcharge, and soil weight.

3. Importance of Unit Weight Calculation

Details: Accurate unit weight estimation is crucial for foundation design, slope stability analysis, and earthwork calculations.

4. Using the Calculator

Tips: Enter all required parameters. Bearing capacity factors typically have ±5% variability. Ensure width of footing is in meters.

5. Frequently Asked Questions (FAQ)

Q1: What is local shear failure?
A: Local shear failure occurs when the soil fails only beneath the foundation with some bulging, unlike general shear failure.

Q2: Why is the 2/3 factor applied to cohesion?
A: For local shear failure, only a portion of the full cohesion is mobilized, hence the reduction factor.

Q3: How do I determine bearing capacity factors?
A: They depend on soil friction angle. Use standard tables or our Bearing Capacity Factor Calculator.

Q4: What if my soil has no cohesion (C=0)?
A: Simply enter 0 for cohesion - the calculator will handle it appropriately.

Q5: What are typical values for unit weight of soil?
A: Typically ranges from 16-22 kN/m³ for most soils, but can vary significantly.