Abstract
In hot-humid regions, granite residual soil’s moisture and free iron oxide contents show marked spatiotemporal heterogeneity tied to seasons and weathering, creating an inherent connection between its visual color and mechanical properties. This study carried out indoor chromaticity parameter measurements and shear strength tests on residual granite soils in southeastern Guangxi with varying moisture and free iron oxide contents, acquiring CIE-L*a*b* color indices and shear strength parameters. Using path and regression analyses, it explored correlations between chromaticity parameters (L* [lightness], a* [red-green chroma], b* [yellow-blue chroma]) and shear strength indices (internal friction angle φ, cohesion c). Results showed that at constant moisture, rising free iron oxide content positively correlates with cohesion, a* and b*, but not with L*; φ has no significant links to any chromaticity parameter. At fixed free iron oxide content, cohesion has a nonlinear correlation with L*, a* and b* as moisture increases, while φ is significantly positively correlated with these chromaticity indices. The findings verify that chromaticity parameters can effectively and rapidly estimate granite residual soil’s shear strength, providing valuable references for geotechnical evaluations.
Data availability
All data, models, and codes generated or used during the study appear in the published article.
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Acknowledgements
The authors are grateful for the financial support provided by the National Natural Science Foundation of China (42167021).
Funding
This research was funded by the National Natural Science Foundation of China (NSFC) (grant number 42167021).
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Conceptualization, writing—original draft, supervision, Z.W.; Supervision, visualization, writing—original draft, W.D.; Investigation, data curation, validation, C.D.; Methodology, resources, validation, X.K.; Investigation, software, J.Y. All authors have read and agreed to the published version of the manuscript.
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Wang, Z., Deng, W., Diao, C. et al. Correlations between chromaticity parameters and shear strength of granite residual soil with different free iron oxide content and moisture content. Sci Rep (2026). https://doi.org/10.1038/s41598-026-38135-0
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DOI: https://doi.org/10.1038/s41598-026-38135-0
