Unit Weight of Soil given Safe Bearing Capacity Calculator

Unit Weight of Soil Formula:

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

Safe Bearing Capacity:

kPa

Factor of Safety:

Effective Surcharge:

kPa

Cohesion in Soil:

kPa

Bearing Capacity Factor (Cohesion):

Bearing Capacity Factor (Surcharge):

Width of Footing:

Bearing Capacity Factor (Unit Weight):

Unit Weight of Soil (kN/m³):

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

Definition: This calculator determines the unit weight of soil based on the safe bearing capacity and other soil parameters.

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:

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

Where:

\( \gamma \) — Unit weight of soil (kN/m³)
\( q_{sa} \) — Safe bearing capacity (kPa)
\( fs \) — Factor of safety
\( \sigma_s \) — Effective surcharge (kPa)
\( C \) — Cohesion in soil (kPa)
\( N_c \) — Bearing capacity factor (cohesion)
\( N_q \) — Bearing capacity factor (surcharge)
\( B \) — Width of footing (m)
\( N_\gamma \) — Bearing capacity factor (unit weight)

Explanation: The formula calculates the unit weight by considering the balance between bearing capacity and soil properties.

3. Importance of Unit Weight Calculation

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

4. Using the Calculator

Tips: Enter all required parameters with appropriate values. The ±5% indicates the typical accuracy range for these parameters.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical factor of safety?
A: Common values range from 2.5 to 3.5 depending on soil conditions and design requirements.

Q2: How do I determine effective surcharge?
A: It's calculated based on the weight of overlying materials above the foundation level.

Q3: What affects cohesion in soil?
A: Cohesion depends on soil type, moisture content, and compaction. Clay soils typically have higher cohesion than sandy soils.

Q4: How is footing width determined?
A: Footing width is based on structural loads and soil bearing capacity, typically ranging from 0.5m to 3m for residential construction.

Q5: Why are bearing capacity factors important?
A: These dimensionless factors account for soil shear strength characteristics in bearing capacity calculations.