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Background <p>Extreme weather events, such as heavy rainfall, can trigger landslides in granite residual soil (GRS) slopes due to its high porosity and dense vegetation, which facilitate the formation of preferential flow pathways. However, the dynamic evolution of seepage-dominant channels and the mechanisms of fine particle erosion in GRS under short-term heavy rainfall remain poorly understood.</p> Aims and methods <p>This study focuses on GRS, utilizing <i>in-situ</i> dynamic contrast computed tomography (CT) scanning technology to extract the internal pore network model under seepage conditions. By integrating over-seepage theory with erosion and expansion algorithms, the over-seepage threshold was determined to elucidate fine particle erosion pathways at a microscopic level.</p> Results <p>Under hydraulic pressure, isolated pores gradually connect to surrounding pores. The mean pore equivalent radius increased by 3.96%–9.48%, the mean pore throat equivalent radius rose by 10.88%–23.10%, and the mean coordination number increased by 9.36%–17.54%. The over-seepage thresholds for Fuzhou and Nanping samples decreased by 10.34% and 4.47%, respectively, highlighting the significant spatial variability in GRS pore structure.</p> Conclusion <p>When GRS is subjected to seepage, fine particle erosion predominantly occurs within dominant channels. Continuous fine particle loss due to hydraulic forces widens these channels along the flow direction, enhancing dominant flow and establishing a “dominant flow–dominant channel” spatiotemporal feedback mechanism.</p> Significance <p>This study provides a novel approach for understanding the seepage mechanisms of GRS and predicting its engineering properties, offering critical insights for the design and construction of GRS-related engineering projects.</p> Graphical abstract <p></p>

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Dynamic evolution of dominant channels and fine particle migration paths in granitie residual soil under seepage coupling using in-situ dynamic contrast CT scanning

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Yun Que,
  • Jin Tang,
  • Ting Qiu,
  • Zhenliang Jiang,
  • Shanghui Li,
  • Bin Weng,
  • Jianbin Liu

摘要

Background

Extreme weather events, such as heavy rainfall, can trigger landslides in granite residual soil (GRS) slopes due to its high porosity and dense vegetation, which facilitate the formation of preferential flow pathways. However, the dynamic evolution of seepage-dominant channels and the mechanisms of fine particle erosion in GRS under short-term heavy rainfall remain poorly understood.

Aims and methods

This study focuses on GRS, utilizing in-situ dynamic contrast computed tomography (CT) scanning technology to extract the internal pore network model under seepage conditions. By integrating over-seepage theory with erosion and expansion algorithms, the over-seepage threshold was determined to elucidate fine particle erosion pathways at a microscopic level.

Results

Under hydraulic pressure, isolated pores gradually connect to surrounding pores. The mean pore equivalent radius increased by 3.96%–9.48%, the mean pore throat equivalent radius rose by 10.88%–23.10%, and the mean coordination number increased by 9.36%–17.54%. The over-seepage thresholds for Fuzhou and Nanping samples decreased by 10.34% and 4.47%, respectively, highlighting the significant spatial variability in GRS pore structure.

Conclusion

When GRS is subjected to seepage, fine particle erosion predominantly occurs within dominant channels. Continuous fine particle loss due to hydraulic forces widens these channels along the flow direction, enhancing dominant flow and establishing a “dominant flow–dominant channel” spatiotemporal feedback mechanism.

Significance

This study provides a novel approach for understanding the seepage mechanisms of GRS and predicting its engineering properties, offering critical insights for the design and construction of GRS-related engineering projects.

Graphical abstract