Unit Weight of Soil given Value of Bearing Capacity Factor Calculator

Unit Weight of Soil Formula:

\[ \gamma = \frac{q_f - (C_s \times 5.7)}{D} \]

Ultimate Bearing Capacity:

kPa

Cohesion of Soil:

kPa

Depth of Footing:

Tolerance:

Unit Weight of Soil (kN/m³):

1. What is Unit Weight of Soil given Bearing Capacity Factor?

Definition: This calculator determines the unit weight of soil based on ultimate bearing capacity, soil cohesion, and footing depth.

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

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \gamma = \frac{q_f - (C_s \times 5.7)}{D} \]

Where:

\( \gamma \) — Unit weight of soil (kN/m³)
\( q_f \) — Ultimate bearing capacity (kPa)
\( C_s \) — Cohesion of soil (kPa)
\( D \) — Depth of footing (m)

Explanation: The formula accounts for the bearing capacity factor (5.7) for cohesive soils and calculates the unit weight needed to achieve the specified bearing capacity.

3. Importance of Unit Weight Calculation

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

4. Using the Calculator

Tips: Enter the ultimate bearing capacity, soil cohesion, footing depth, and tolerance percentage (default ±5%). All values must be ≥ 0 except capacity and depth which must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the 5.7 factor in the formula?
A: It's the bearing capacity factor (Nc) for cohesive soils under shallow foundations, typically taken as 5.7 for long footings.

Q2: When would cohesion be zero?
A: For cohesionless soils like sand or gravel where shear strength comes primarily from friction rather than cohesion.

Q3: What's a typical unit weight range for soils?
A: Most soils range from 16-22 kN/m³, with clays at the higher end and loose sands at the lower end.

Q4: Why include a tolerance percentage?
A: Soil properties can vary naturally, so the tolerance helps account for this variability in design calculations.

Q5: How does footing depth affect the calculation?
A: Deeper footings generally require lower unit weights to achieve the same bearing capacity due to increased overburden pressure.