1. What is Pore Water Pressure given Pore Pressure Ratio?

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

Purpose: It helps geotechnical engineers analyze slope stability by quantifying the effect of pore water pressure.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( F_u \) — Upward force due to seepage (Pascals)
• \( r_u \) — Pore pressure ratio (dimensionless, 0-1)
• \( \gamma \) — Unit weight of soil (N/m³)
• \( z \) — Height of slice (meters)

Explanation: The pore pressure ratio represents the proportion of normal stress that is taken by pore water pressure.

3. Importance of Pore Water Pressure Calculation

Details: Accurate pore water pressure estimation is crucial for slope stability analysis, as it reduces effective stress and shear strength.

4. Using the Calculator

Tips: Enter the pore pressure ratio (0-1), unit weight of soil (default 18000 N/m³), and height of slice (default 3 m). All values must be > 0 except ratio which can be 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical pore pressure ratio range?
A: The ratio typically ranges from 0 (dry soil) to 0.5 (partially saturated) to 1 (fully saturated).

Q2: How is unit weight of soil determined?
A: It's measured through laboratory tests or estimated from soil classification (e.g., 18-20 kN/m³ for many soils).

Q3: What does the height of slice represent?
A: This is the vertical dimension of the soil section being analyzed in slope stability calculations.

Q4: Why is upward force important?
A: It counteracts the downward force of soil, reducing effective stress and potentially causing slope failure.

Q5: How does this relate to factor of safety?
A: Higher upward forces decrease the factor of safety against slope failure.

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