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<p>The mechanical properties of rockfill materials degrade markedly under dry–wet cycles, leading to uneven settlement of rockfill dams over time. To elucidate the underlying mechanisms, this study utilizes the particle discrete element method (DEM) to conduct numerical simulations of triaxial compression on crushable rockfill samples under various dry–wet cycle scenarios. This computational approach facilitates a comprehensive analysis of the material's macroscopic mechanical behavior while simultaneously revealing its microscopic degradation processes. The research findings are presented in detail below: (1) Macroscopic law: The results indicate that an increase in the number of dry–wet cycles (<i>N</i>) corresponds with a decrease in peak stress and an increase in volume strain. However, these parameters tend to stabilize, showing minimal change once <i>N</i> exceeds a certain threshold. Furthermore, the analysis reveals an exponential relationship between <i>N</i> and the key shear strength parameters: the apparent cohesion (<i>c</i>) and the internal friction angle (<i>φ</i>). Concurrently, as the cycles progress, both the rate of particle breakage (<i>B</i><sub>r</sub>) and the net increase in particle count progressively diminish. (2) Microscopic mechanism: An increase in <i>N</i> leads to the expansion of force chain networks, a wider distribution of particle fractures, and a more extensive displacement field within the sample, accompanied by a significant rise in the average coordination number. Mirroring the macroscopic behavior, these microscopic changes also become less pronounced after <i>N</i> surpasses the established threshold, suggesting the sample is approaching a state of mechanical stability. (3) Damage evolution: Analysis of the modified Duncan-Chang model reveals that its constitutive parameters (<i>A</i>, <i>B</i>, and <i>C</i>) demonstrate an exponential relationship with the number of dry–wet cycles (<i>N</i>). These parameters undergo a phase of rapid exponential growth during the initial cycles, which subsequently transitions to a stable state as the cycling progresses.</p>

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Study on the evolution law and numerical simulation of the mechanical properties of rockfill under dry–wet cycle conditions

  • 期刊论文

  • 发表日期：

    2026年1月29日

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  • Rongxian Yang,
  • Lingkai Zhang,
  • Chong Shi,
  • Runhan Zhang

摘要

The mechanical properties of rockfill materials degrade markedly under dry–wet cycles, leading to uneven settlement of rockfill dams over time. To elucidate the underlying mechanisms, this study utilizes the particle discrete element method (DEM) to conduct numerical simulations of triaxial compression on crushable rockfill samples under various dry–wet cycle scenarios. This computational approach facilitates a comprehensive analysis of the material's macroscopic mechanical behavior while simultaneously revealing its microscopic degradation processes. The research findings are presented in detail below: (1) Macroscopic law: The results indicate that an increase in the number of dry–wet cycles (N) corresponds with a decrease in peak stress and an increase in volume strain. However, these parameters tend to stabilize, showing minimal change once N exceeds a certain threshold. Furthermore, the analysis reveals an exponential relationship between N and the key shear strength parameters: the apparent cohesion (c) and the internal friction angle (φ). Concurrently, as the cycles progress, both the rate of particle breakage (Br) and the net increase in particle count progressively diminish. (2) Microscopic mechanism: An increase in N leads to the expansion of force chain networks, a wider distribution of particle fractures, and a more extensive displacement field within the sample, accompanied by a significant rise in the average coordination number. Mirroring the macroscopic behavior, these microscopic changes also become less pronounced after N surpasses the established threshold, suggesting the sample is approaching a state of mechanical stability. (3) Damage evolution: Analysis of the modified Duncan-Chang model reveals that its constitutive parameters (A, B, and C) demonstrate an exponential relationship with the number of dry–wet cycles (N). These parameters undergo a phase of rapid exponential growth during the initial cycles, which subsequently transitions to a stable state as the cycling progresses.