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<p>Argillaceous siltstone ubiquitous in geological formations, exhibits complex mechanical responses under alternating dry–wet (D-W) cycles. Understanding its damage evolution and developing accurate constitutive models are pivotal for long-term stability assessment in geotechnical engineering. This study investigates the deterioration and energy evolution behavior of argillaceous siltstone under D-W cycles using triaxial compression tests (TCT), nuclear magnetic resonance (NMR), and numerical simulations. A novel damage constitutive model is constructed by incorporating a damage variable based on dissipated energy density and introducing a newly defined compaction coefficient to characterize the initial deformation phase. Results show that repeated D-W cycles cause a transition in stress–strain behavior from strain softening to hardening, alongside significant reductions in triaxial compressive strength and elastic modulus. NMR tests reveal a progressive increase in porosity from 9.99% to 13.12% due to internal microstructural instability. Energy analysis indicates a consistent decline in all energy density parameters with increasing D-W cycles. The proposed model demonstrates improved accuracy in reproducing damage evolution characteristics compared to traditional models. Numerical results revealed three distinct stages of crack evolution: crack compaction, crack propagation, and macroscopic failure. The results found in this study provide new insights into the deterioration mechanisms of argillaceous siltstone under cyclic D-W conditions and offer a theoretical reference for related engineering applications.</p>

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Damage Mechanism Evolution of Argillaceous Siltstone Exposed to Dry–Wet Cycles: Experimental, Theoretical and Numerical Study

  • 期刊论文

  • 发表日期：

    2025年8月20日

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  • Kai Huang,
  • Guojun Cai,
  • Fusheng Zha,
  • Bo Kang,
  • Qiao Wang,
  • Yinbin Shen

摘要

Argillaceous siltstone ubiquitous in geological formations, exhibits complex mechanical responses under alternating dry–wet (D-W) cycles. Understanding its damage evolution and developing accurate constitutive models are pivotal for long-term stability assessment in geotechnical engineering. This study investigates the deterioration and energy evolution behavior of argillaceous siltstone under D-W cycles using triaxial compression tests (TCT), nuclear magnetic resonance (NMR), and numerical simulations. A novel damage constitutive model is constructed by incorporating a damage variable based on dissipated energy density and introducing a newly defined compaction coefficient to characterize the initial deformation phase. Results show that repeated D-W cycles cause a transition in stress–strain behavior from strain softening to hardening, alongside significant reductions in triaxial compressive strength and elastic modulus. NMR tests reveal a progressive increase in porosity from 9.99% to 13.12% due to internal microstructural instability. Energy analysis indicates a consistent decline in all energy density parameters with increasing D-W cycles. The proposed model demonstrates improved accuracy in reproducing damage evolution characteristics compared to traditional models. Numerical results revealed three distinct stages of crack evolution: crack compaction, crack propagation, and macroscopic failure. The results found in this study provide new insights into the deterioration mechanisms of argillaceous siltstone under cyclic D-W conditions and offer a theoretical reference for related engineering applications.