PyelogP

"Py e-log(P)" is a lightweight Python library for estimating the preconsolidation pressure ($\sigma'_p$) of oedometer test data using the strain-energy method with knee-point detection and thresholding in the $e$–$log(P)$ space.

Features

• Manual data input or import from a .csv file.
• Automatic removal of unload–reload cycles from input data.
• Physically informed threshold selection for S-shaped $e$–$log(P)$ curves typical of sensitive marine clays, aged clays, and cemented clays.
• Plot void ratio versus $\sigma'_v$ and Work versus Pressure (W-P).

Installation

pip install pyelogp

Clone from GitHub

# Clone the repo
git clone https://github.com/liangchow/pyelogp.git
cd pyelogp

# Create and activate virtual environment
python -m venv .venv
source .venv/bin/activate      # macOS/Linux
.venv\Scripts\activate         # Windows

# Install dependencies
pip install -e .

Quick start

See run.py for a full example, including loading data from a CSV file via Data.from_csv.

from pyelogp import Data

# Louiseville clay
pressure = [59, 90, 120, 150, 165, 172, 184, 222, 300, 400]
void_ratio = [2.115, 2.113, 2.098, 2.083, 2.055, 2, 1.8, 1.5, 1.3, 1.193]
e0 = 2.10 (Optional)
sigmaV0 = 59.0

d = Data(pressure=pressure, void_ratio=void_ratio, e0=e0, sigmaV0=sigmaV0)

# Run analysis
result = d.find_pc()
print("Preconsolidation pressure (Pc):", result.pc)
print("Void ratio at pc (e_pc):", result.e_pc)
print("R² segment 1:", result.r2_seg1)
print("R² segment 2:", result.r2_seg2)

# Return
Preconsolidation pressure (Pc): 164.5
Void ratio at pc (e_pc): 2.0573
R² segment 1: 0.894
R² segment 2: 0.969

Contributing

Contributions are welcome, please refer to CONTRIBUTING to learn more about how to contribute.

References

Becker, D. E., Crooks, J. H. A., Been, K., & Jefferies, M. G. (1987). Work as a Criterion for Determining in situ and Yield Stresses in Clays. Canadian Geotechnical Journal, 24(4), 549–564.

Bonaparte, R. and Mitchell, J.K. (1979). The Properties of San Francisco Bay Mud at Hamilton Air Force Base, California. Geotechnical Engineering Report, University of California, Berkeley, April 1979.

Satopa, V., Albrecht, J., Irwin, D., and Raghavan, B. (2011). Finding a 'Kneedle' in a Haystack: Detecting Knee Points in System Behavior. 31st International Conference on Distributed Computing Systems Workshops, 166-171.

Terzaghi, K., Peck, R.B., & Mesri, G. (1996). Soil Mechanics in Engineering Practice (3rd ed.). John Wiley & Sons, Inc.