Average Unit Weight of Soil given Net Pressure Intensity Calculator

Unit Weight of Soil Formula:

\[ \gamma = \frac{q_g - q_n}{D_{footing}} \]

Unit Weight of Soil (N/m³):

1. What is Unit Weight of Soil?

Definition: Unit Weight of Soil is the ratio of the total weight of soil to the total volume of soil.

Purpose: It helps geotechnical engineers determine the soil's bearing capacity and design appropriate foundations.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \gamma = \frac{q_g - q_n}{D_{footing}} \]

Where:

\( \gamma \) — Unit Weight of Soil (N/m³)
\( q_g \) — Gross Pressure (Pa)
\( q_n \) — Net Pressure (Pa)
\( D_{footing} \) — Depth of Footing in Soil (m)

Explanation: The difference between gross and net pressure is divided by the footing depth to determine the average unit weight of the soil.

3. Importance of Unit Weight Calculation

Details: Accurate unit weight estimation ensures proper foundation design, slope stability analysis, and earthwork calculations.

4. Using the Calculator

Tips: Enter the gross pressure, net pressure (both in Pa), and footing depth (in m). All values must be > 0. The ±5% indicates typical measurement tolerances.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between gross and net pressure?
A: Gross pressure includes all loads on the soil, while net pressure excludes the original soil pressure before construction.

Q2: Why is footing depth important?
A: Footing depth affects how soil pressure is distributed and the effective unit weight calculation.

Q3: What are typical unit weight values for different soils?
A: Clay: 16-22 kN/m³, Sand: 18-21 kN/m³, Gravel: 19-22 kN/m³ (1 kN/m³ = 1000 N/m³).

Q4: How does moisture affect unit weight?
A: Water content increases unit weight up to saturation point, then decreases it as soil becomes buoyant.

Q5: What does the ±5% tolerance mean?
A: It accounts for typical measurement variations in field conditions and laboratory testing.