Unit Weight of Non Cohesive Soil given Bearing Capacity of Strip Footing Calculator

Unit Weight of Soil Formula:

\[ γ = \frac{q_{fc} - (σ_s \times N_q)}{0.5 \times N_γ \times B} \]

Ultimate Bearing Capacity (kPa):

Effective Surcharge (kPa):

Bearing Capacity Factor (Surcharge):

Bearing Capacity Factor (Unit Weight):

Width of Footing (m):

Unit Weight of Soil (kN/m³):

1. What is Unit Weight of Non Cohesive Soil?

Definition: Unit weight of non-cohesive soil (like sand or gravel) is the weight per unit volume of soil, crucial for foundation design.

Purpose: This calculator determines the unit weight based on bearing capacity of strip footing and other soil parameters.

2. How Does the Calculator Work?

The calculator uses the bearing capacity formula:

\[ γ = \frac{q_{fc} - (σ_s \times N_q)}{0.5 \times N_γ \times B} \]

Where:

\( γ \) — Unit weight of soil (kN/m³)
\( q_{fc} \) — Ultimate bearing capacity (kPa)
\( σ_s \) — Effective surcharge (kPa)
\( N_q \) — Bearing capacity factor for surcharge
\( N_γ \) — Bearing capacity factor for unit weight
\( B \) — Width of footing (m)

Explanation: The formula calculates the soil unit weight needed to achieve the specified bearing capacity.

3. Importance of Unit Weight Calculation

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

4. Using the Calculator

Tips: Enter all required parameters. Default values are provided for bearing capacity factors. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical unit weight for non-cohesive soils?
A: Sandy soils typically range from 16-20 kN/m³, while gravelly soils range from 18-22 kN/m³.

Q2: How do I determine bearing capacity factors?
A: Factors depend on soil friction angle. Use tables or our Bearing Capacity Factor Calculator.

Q3: Why is effective surcharge important?
A: It accounts for overburden pressure from adjacent structures or soil layers above foundation level.

Q4: What if my soil is cohesive?
A: This calculator is for non-cohesive soils only. Different formulas apply for clayey soils.

Q5: How accurate are the results?
A: Results are theoretical estimates. Field tests (like SPT or CPT) provide more accurate values.