Overall Pore Pressure Coefficient Calculator

Pore Pressure Coefficient Formula:

\[ B = \frac{\Delta u}{\Delta \sigma_1} \]

Pore Pressure Coefficient (B):

Pore Pressure Coefficient (%):

1. What is the Overall Pore Pressure Coefficient?

Definition: The pore pressure coefficient (B) is the ratio of change in pore pressure to change in normal stress under undrained conditions.

Purpose: It helps geotechnical engineers understand how changes in stress affect pore water pressure in soils and rocks.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ B = \frac{\Delta u}{\Delta \sigma_1} \]

Where:

\( B \) — Pore pressure coefficient (dimensionless)
\( \Delta u \) — Change in pore pressure (Pa)
\( \Delta \sigma_1 \) — Change in normal stress (Pa)

Explanation: The coefficient indicates how much of the applied stress is transferred to the pore water versus the soil skeleton.

3. Importance of Pore Pressure Coefficient

Details: Understanding B is crucial for analyzing soil behavior under loading, predicting consolidation, and assessing slope stability.

4. Using the Calculator

Tips: Enter the change in pore pressure (Δu) and change in normal stress (Δσ₁) in Pascals. The calculator provides both decimal and percentage results.

5. Frequently Asked Questions (FAQ)

Q1: What does a B value of 1 mean?
A: B = 1 indicates all applied stress is transferred to pore water (fully saturated soil with incompressible fluid).

Q2: What's a typical B value for saturated clay?
A: For saturated clay, B typically ranges between 0.95-1.0 (95-100%).

Q3: What does B = 0 indicate?
A: B = 0 means no pore pressure change occurs (dry or very stiff soil).

Q4: How is this different from Skempton's B parameter?
A: This is Skempton's B parameter - it's the same concept measuring pore pressure response to total stress change.

Q5: Why is the percentage value important?
A: The percentage shows what portion of the stress change is carried by pore water versus the soil skeleton.