Height of Slice given Pore Pressure Ratio Calculator

Height of Slice Formula:

\[ z = \frac{F_u}{r_u \times \gamma} \]

Height of Slice (m):

1. What is Height of Slice given Pore Pressure Ratio?

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

Purpose: It helps geotechnical engineers analyze slope stability by calculating slice dimensions under seepage conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ z = \frac{F_u}{r_u \times \gamma} \]

Where:

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

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

3. Importance of Slice Height Calculation

Details: Accurate slice height determination is crucial for slope stability analysis, especially when considering pore water pressure effects.

4. Using the Calculator

Tips: Enter the upward seepage force in Pascals, pore pressure ratio (default 0.9 ±5%), and soil unit weight (default 18000 N/m³). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for pore pressure ratio?
A: Pore pressure ratio typically ranges from 0 to 1, with 0.9 being a common value for many soils (±5% variation).

Q2: How do I determine the upward seepage force?
A: Upward seepage force can be calculated from hydraulic gradient and unit weight of water, or measured in field tests.

Q3: What affects the unit weight of soil?
A: Soil composition, moisture content, and compaction level all influence unit weight. Typical values range from 16,000 to 22,000 N/m³.

Q4: Why is slice height important in stability analysis?
A: Slice height affects the weight and pore pressure calculations for each slice in methods like Bishop's or Janbu's.

Q5: How does pore pressure ratio affect the results?
A: Higher pore pressure ratios result in smaller calculated slice heights, indicating greater influence of pore water pressure.