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<p>The Neogene red-bed sandstone in the tectonically active Guide Basin (NE Tibetan Plateau) represents a critical lithology governing recurrent landslide hazards. This study unravels the hydro-chemo-mechanical coupling mechanisms driving its degradation under cyclic wetting–drying (CWD). Integrating XRD, SEM, CT, and uniaxial compression analyses, CWD induced alterations in mineralogical composition, pore-fracture evolution, and strength deterioration are quantified. Results demonstrate that feldspar hydrolysis and kaolinite dissolution dominate mineralogical transformations, reducing feldspar content by 62.1% and kaolinite by 10.9% after 10 CWD cycles. Concurrently, micro-CT and SEM analyses reveal progressive pore coalescence (porosity increase: 5.59% → 15.13%) and fracture network development, transitioning isolated pores to interconnected pathways. These micro-meso structural changes drive nonlinear reductions in peak strength (σ<sub>c</sub>: 11.87 → 4.28 MPa, 64% loss) and elastic modulus (E: 11.33 → 2.17 GPa, 80.8% decline). Strong correlations (Pearson’s r = − 0.89 to − 0.99) between feldspar depletion, fracture density, and σ<sub>c</sub>/E reduction confirm that disaster-prone degradation arises from synergistic multi-scale processes: mineral dissolution initiates microcracking, pore-fracture coalescence enables fluid ingress, and hydro-mechanical feedback accelerates macroscale failure. This work establishes a genetic framework linking mineralogical gene alterations to catastrophic slope instability in arid-semiarid rift basins, providing critical insights for geohazard mitigation in analogous Tibetan Plateau regions.</p>

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Cyclic Wetting–Drying Driven Geological Gene Changes and Multi-scale Degradation Mechanisms of the Neogene Red-Bed Sandstone in the Guide Basin, NE Tibetan Plateau

  • 期刊论文

  • 发表日期：

    2025年7月8日

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  • Yezi Quan,
  • Zuopeng Wang,
  • Jianbing Peng,
  • Yiguo Xue,
  • Mingdong Zang,
  • Changming Lu,
  • Ruihao Ning

摘要

The Neogene red-bed sandstone in the tectonically active Guide Basin (NE Tibetan Plateau) represents a critical lithology governing recurrent landslide hazards. This study unravels the hydro-chemo-mechanical coupling mechanisms driving its degradation under cyclic wetting–drying (CWD). Integrating XRD, SEM, CT, and uniaxial compression analyses, CWD induced alterations in mineralogical composition, pore-fracture evolution, and strength deterioration are quantified. Results demonstrate that feldspar hydrolysis and kaolinite dissolution dominate mineralogical transformations, reducing feldspar content by 62.1% and kaolinite by 10.9% after 10 CWD cycles. Concurrently, micro-CT and SEM analyses reveal progressive pore coalescence (porosity increase: 5.59% → 15.13%) and fracture network development, transitioning isolated pores to interconnected pathways. These micro-meso structural changes drive nonlinear reductions in peak strength (σc: 11.87 → 4.28 MPa, 64% loss) and elastic modulus (E: 11.33 → 2.17 GPa, 80.8% decline). Strong correlations (Pearson’s r = − 0.89 to − 0.99) between feldspar depletion, fracture density, and σc/E reduction confirm that disaster-prone degradation arises from synergistic multi-scale processes: mineral dissolution initiates microcracking, pore-fracture coalescence enables fluid ingress, and hydro-mechanical feedback accelerates macroscale failure. This work establishes a genetic framework linking mineralogical gene alterations to catastrophic slope instability in arid-semiarid rift basins, providing critical insights for geohazard mitigation in analogous Tibetan Plateau regions.