Quantitative Evaluation of Soil Structure and Strain in Three Dimensions under Shear Using X-ray Computed Tomography
Shintaro Nohara1,2, Toshifumi Mukunoki3
1Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi 270-1194, Chiba, Japan.
Journal of Imaging
|November 25, 2021
Summary
This study quantitatively evaluated soil structure behavior under shear stress using micro-focus X-ray computed tomography (CT). Findings reveal particle reorientation within a narrow shear zone, offering insights into shear band formation mechanisms.
Area of Science:
- Geotechnical Engineering
- Soil Mechanics
- Material Science
Background:
- Understanding soil shear behavior is crucial for infrastructure stability.
- Shear zone formation mechanisms in granular materials remain complex.
- Non-invasive imaging techniques can provide detailed microstructural insights.
Purpose of the Study:
- To quantitatively analyze soil structure evolution during shear.
- To investigate the mechanism of shear zone formation.
- To develop and validate a novel image-analysis method for soil microstructure.
Main Methods:
- Micro-focus X-ray computed tomography (CT) for non-destructive internal visualization.
- Direct shear experiments on soil samples.
- A new image-analysis technique fitting particles as ellipsoids to determine length and direction.
- Digital image correlation (DIC) for strain analysis.
Main Results:
- A new image-analysis method was developed and validated for evaluating particle orientation and length.
- Shear zone width was approximately 7.1 times the median grain size.
- Particle reorientation was observed, primarily within a narrow region near the shear plane.
- Significant particle direction changes occurred after peak shear stress and volume expansion.
Conclusions:
- The study provides quantitative insights into soil structure behavior under shear stress.
- The developed image-analysis method effectively characterizes microstructural changes in shear zones.
- Shear zone formation involves localized particle reorientation within a confined region.
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