Unit weight of Soil given Pore Pressure Ratio Calculator

Unit Weight of Soil Formula:

\[ γ = \frac{F_u}{r_u \times z} \]

Unit Weight of Soil (N/m³):

1. What is Unit Weight of Soil given Pore Pressure Ratio?

Definition: This calculator determines the unit weight of soil based on upward seepage force, pore pressure ratio, and height of soil slice.

Purpose: It helps geotechnical engineers analyze soil stability and seepage conditions in slope stability analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ γ = \frac{F_u}{r_u \times z} \]

Where:

\( γ \) — Unit weight of soil (N/m³)
\( F_u \) — Upward force due to seepage (Pa)
\( r_u \) — Pore pressure ratio (dimensionless, typically 0-1)
\( z \) — Height of soil slice (m)

Explanation: The upward seepage force is divided by the product of pore pressure ratio and slice height to determine the soil's unit weight.

3. Importance of Unit Weight Calculation

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

4. Using the Calculator

Tips: Enter the upward seepage force in Pascals, pore pressure ratio (default 0.9), and slice height in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is pore pressure ratio (r_u)?
A: It's the ratio of pore water pressure to the total vertical stress in the soil, ranging from 0 (dry) to 1 (fully saturated).

Q2: Typical values for unit weight of soil?
A: Most soils range from 15-22 kN/m³ (15,000-22,000 N/m³), but this varies with soil type and moisture content.

Q3: How is upward seepage force determined?
A: It's calculated from the hydraulic gradient and unit weight of water in seepage analysis.

Q4: When would pore pressure ratio be close to 1?
A: In fully saturated soils under rapid loading conditions where water can't drain quickly.

Q5: What affects the height of slice in analysis?
A: It depends on the problem geometry and the method of slices being used in the stability analysis.