1. What is Change in Pore Pressure?

Definition: This calculator determines the change in pore water pressure resulting from changes in normal stress, using the overall pore pressure coefficient.

Purpose: Essential for geotechnical engineering analyses involving soil mechanics and groundwater flow.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \Delta u \) — Change in pore pressure (Pascals)
• \( \Delta \sigma_1 \) — Change in normal stress (Pascals)
• \( B \) — Overall pore pressure coefficient (dimensionless, 0-1)

Explanation: The change in normal stress is multiplied by the pore pressure coefficient to determine the resulting pore pressure change.

3. Importance of Pore Pressure Calculation

Details: Accurate pore pressure calculations are critical for slope stability analysis, foundation design, and understanding soil behavior under loading.

4. Using the Calculator

Tips: Enter the change in normal stress in Pascals and the pore pressure coefficient (default 0.5, range 0-1). The coefficient has ±5% uncertainty.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for pore pressure coefficient B?
A: For saturated soils, B typically ranges from 0.95 to 1. For unsaturated soils, it can be much lower (0-0.5).

Q2: Why is there a ±5% uncertainty?
A: The coefficient can vary due to soil heterogeneity, degree of saturation, and stress history.

Q3: How is change in normal stress determined?
A: It's the difference between final and initial vertical effective stresses in the soil mass.

Q4: What affects the pore pressure coefficient?
A: Soil type, saturation level, compressibility, and stress path all influence B.

Q5: When would pore pressure change be negative?
A: When normal stress decreases (e.g., excavation) or when soil dilates under shear.

Change in Pore Pressure Calculator© - All Rights Reserved 2025