Disturbance function for soil disturbed state strength based on X-ray computed tomography triaxial test.

Area of Science:

• Geotechnical Engineering
• Soil Mechanics
• Imaging Science

Background:

• Soil structure is significantly impacted by biological activity, leading to cracks and macro-pores.
• These structural changes affect soil strength and land degradation.
• X-ray computed tomography (CT) provides quantitative data, including mean density (MD) and standard deviation (SD) values, to assess soil disturbance.

Purpose of the Study:

• To quantitatively investigate two disturbance functions (MD and SD values) for analyzing soil disturbed state strength.
• To compare the effectiveness of MD and SD based disturbance functions in relation to macro-pore characteristics.

Main Methods:

• CT-triaxial testing was performed on five soil samples: four disturbed with varying macro-pore sizes and one undisturbed.
• Quantitative analysis of CT images focused on mean density (MD) and standard deviation (SD) values.
• Correlation between shear strength, macro-pore characteristics, and disturbance functions was examined.

Main Results:

• Shear strength was consistent among disturbed samples with identical macro-pore sizes.
• The SD value and its derived disturbance function showed a strong correlation with macro-pore cross-sectional area.
• The MD value and its derived disturbance function did not exhibit a clear relationship with macro-pore size.

Conclusions:

• The disturbance function based on the SD value is more suitable for analyzing soil disturbed state strength using CT morphometry.
• The disturbance function defined by the MD value is less appropriate for soil strength analysis but has been used for rock damage characterization.