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Valverde, Ana Maria

University of British Columbia

The findings from laboratory element testing research conducted at the University of British Columbia has shown the significant effect of particle structure (fabric) on the monotonic and cyclic shear behavior of silty soils, alongside the well-known impacts from factors such as void ratio and confining stress. Fine-grained silty soils are susceptible to earthquake-induced softening and strength reduction, posing critical geotechnical hazards to structures founded on such soils. At present, conventional geotechnical approaches often neglect the particulate structure of soil, leading to potentially undesirable designs in terms of safety and/or construction economy. Since traditional destructive techniques have not successfully provided adequate visualization of particle configuration, non-destructive imaging has become increasingly popular. Although significant research has been conducted to understand the structure of coarse-grained soils, imaging for particle analysis of fine-grained particles has been rarely undertaken. This study employed X-ray micro CT to investigate silt-sized particles to bridge this gap, focusing on systematic particle fabric quantification within a silt matrix. Due to the lack of previous experimental knowledge for micro CT imaging of silts, material-specific methodologies were developed for X-ray micro CT of silt-sized particles. In this, attention was given to sample preparation, scanning parameters for image resolution, and digital processing to capture particle data. The ability of micro CT to effectively capture individual particle parameters and the three-dimensional fabric of silt is demonstrated. The particle fabric in terms of orientation in reconstituted specimens is illustrated using standard-size silica particles. The fabric(s) quantified from the imaging of a natural low plastic silt is also presented, and the findings are in accord with those inferred from the mechanical laboratory element testing of the same silt. The applicability of micro CT in characterizing particle fabric and measuring localized void ratios is also established. With the advancements made herein, X-ray micro CT imaging coupled with advanced image processing offers a promising new approach for studying silt fabric. The findings pave an avenue to fundamentally explore the effects of fabric on the stress-strain behavior of soils using the knowledge from “real” silt particle matrices (from micro CT imaging) instead of relying solely on macro-level laboratory tests.

Text

2024-01-04

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87089

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/