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<p>Bentonite is widely used as an engineered barrier in a multi-barrier geological disposal system because of its hydraulic, chemical, and mechanical functions. However, excavation-induced fractures and microfractures can create groundwater flow pathways, making it essential to understand bentonite’s expansion and mechanical behavior under constant-volume conditions and varying moisture contents. This study proposes a novel interlayer slip mechanism to explain bentonite’s micro-deformation, complementing existing cracking and fractal theories. The mechanism was examined through theoretical analysis and validated by specific surface area, swelling, and direct shear tests. Results show that the specific surface area increases with moisture content, with a sharp rise at 25–30% moisture content for high-dry-density samples, confirming interlayer slip. Swelling tests revealed that interlayer slip promotes secondary swelling, while direct shear tests demonstrated a transition from strain softening to strain hardening with increasing vertical pressure. These findings provide new insights into bentonite’s microscopic deformation, swelling behavior, and strength, supporting the development of constitutive models for repository design.</p>

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Interlayer Slip Mechanisms in Bentonite and Their Influence on Mechanical and Swelling Behavior

  • 期刊论文

  • 发表日期：

    2026年2月23日

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  • Hemin Liu,
  • M. A. M. Ismail,
  • Jianwen Zhang

摘要

Bentonite is widely used as an engineered barrier in a multi-barrier geological disposal system because of its hydraulic, chemical, and mechanical functions. However, excavation-induced fractures and microfractures can create groundwater flow pathways, making it essential to understand bentonite’s expansion and mechanical behavior under constant-volume conditions and varying moisture contents. This study proposes a novel interlayer slip mechanism to explain bentonite’s micro-deformation, complementing existing cracking and fractal theories. The mechanism was examined through theoretical analysis and validated by specific surface area, swelling, and direct shear tests. Results show that the specific surface area increases with moisture content, with a sharp rise at 25–30% moisture content for high-dry-density samples, confirming interlayer slip. Swelling tests revealed that interlayer slip promotes secondary swelling, while direct shear tests demonstrated a transition from strain softening to strain hardening with increasing vertical pressure. These findings provide new insights into bentonite’s microscopic deformation, swelling behavior, and strength, supporting the development of constitutive models for repository design.