Unit Weight of Soil given Square Footing and Bearing Capacity Calculator

Unit Weight of Soil Formula:

\[ \gamma = \frac{q_s - ((1.3 \times C_{sq} \times N_c) + (\sigma_{square} \times N_q))}{0.5 \times N_\gamma \times B_{square} \times 0.8} \]

Bearing Capacity (qs):

Cohesion of Soil (Csq):

Bearing Capacity Factor (Nc):

Effective Surcharge (σsquare):

Bearing Capacity Factor (Nq):

Bearing Capacity Factor (Nγ):

Width of Footing (Bsquare):

Unit Weight of Soil (γ):

1. What is Unit Weight of Soil Calculator?

Definition: This calculator determines the unit weight of soil based on bearing capacity, soil cohesion, effective surcharge, and footing dimensions.

Purpose: It helps geotechnical engineers and construction professionals analyze soil properties for foundation design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \gamma = \frac{q_s - ((1.3 \times C_{sq} \times N_c) + (\sigma_{square} \times N_q))}{0.5 \times N_\gamma \times B_{square} \times 0.8} \]

Where:

\( \gamma \) — Unit weight of soil (N/m³)
\( q_s \) — Bearing capacity (Pa)
\( C_{sq} \) — Cohesion of soil (Pa)
\( N_c, N_q, N_\gamma \) — Bearing capacity factors (±5%)
\( \sigma_{square} \) — Effective surcharge (Pa)
\( B_{square} \) — Width of footing (m)

3. Importance of Unit Weight Calculation

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

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Bearing capacity factors typically have ±5% variability.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for bearing capacity factors?
A: Nc ≈ 1.93, Nq ≈ 2.01, Nγ ≈ 1.6 (may vary based on soil type and angle of internal friction).

Q2: Why is there a ±5% on bearing capacity factors?
A: These factors are empirically derived and have inherent variability based on soil conditions.

Q3: How do I determine effective surcharge?
A: It's the vertical stress at footing base level from overlying soil layers or surface loads.

Q4: What units should I use?
A: Use consistent units - Pascals (Pa) for pressures, meters (m) for dimensions, N/m³ for unit weight.

Q5: When would this calculation be needed?
A: During foundation design when you need to back-calculate soil properties from bearing capacity.