Dry Unit Weight Given Porosity Calculator

Formula Used:

\[ \gamma_{dry} = (1 - \eta) \times G_s \times \gamma_w \]

Porosity in Soil Mechanics (η):

(dimensionless)

Specific Gravity of Soil (Gₛ):

(dimensionless)

Unit Weight of Water (γw):

N/m³

Dry Unit Weight (γ_dry):

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1. What is Dry Unit Weight?

Dry Unit Weight of soil is the weight of soil solids per unit of total volume of soil mass. It represents the density of the soil particles alone, excluding any water content.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \gamma_{dry} = (1 - \eta) \times G_s \times \gamma_w \]

Where:

\( \gamma_{dry} \) — Dry Unit Weight (N/m³)
\( \eta \) — Porosity in Soil Mechanics (dimensionless)
\( G_s \) — Specific Gravity of Soil (dimensionless)
\( \gamma_w \) — Unit Weight of Water (N/m³)

Explanation: The formula calculates the dry unit weight by considering the solid fraction of the soil (1-η), multiplied by the specific gravity of soil solids and the unit weight of water.

3. Importance of Dry Unit Weight Calculation

Details: Dry unit weight is a fundamental parameter in geotechnical engineering used for compaction control, settlement analysis, and foundation design. It helps determine the density and strength characteristics of soil.

4. Using the Calculator

Tips: Enter porosity as a decimal between 0 and 1, specific gravity of soil (typically 2.6-2.8 for most soils), and unit weight of water (9810 N/m³ for standard conditions). All values must be positive and within valid ranges.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of dry unit weight for soils?
A: Dry unit weight typically ranges from 12-22 kN/m³ (12,000-22,000 N/m³) for most natural soils, depending on soil type and compaction.

Q2: How does porosity affect dry unit weight?
A: Higher porosity results in lower dry unit weight as there are more voids and less solid material per unit volume.

Q3: What is the difference between dry unit weight and bulk unit weight?
A: Dry unit weight considers only the solid particles, while bulk unit weight includes both solids and water in the voids.

Q4: Why is specific gravity important in this calculation?
A: Specific gravity represents the density of soil solids relative to water, which is essential for converting between mass and volume relationships.

Q5: When is dry unit weight measurement most important?
A: Dry unit weight is crucial in compaction projects, earthwork construction, and when assessing the bearing capacity of soils for foundation design.