Study on Complex Mechanical Behavior of Coarse Granular Materials Based on Continuous-Discontinuous Deformation Analysis
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摘要:
为系统揭示堆石坝粗粒料的细观力学机制和宏观力学响应机理，克服传统连续介质方法在力链演化与颗粒破碎模拟方面的局限性，发展了一种适用于粗粒料三轴试验的连续-非连续变形分析方法. 该方法在传统非连续变形分析方法（DDA）基础上，引入混合位移模式以区分不同块体的力学响应；采用临界阻尼加速计算收敛，并提出新的连续-非连续模拟技术以刻画颗粒破碎过程；通过常规三轴数值试验系统分析粗粒料在加载过程中的变形演化、力链发展、颗粒破碎及剪切带形成等力学行为，重点探讨尺寸效应与端部摩阻力的影响. 结果表明：该方法模拟结果与试验数据结果吻合良好，能够有效反映粗粒料的宏观力学响应与细观机制；围压0.4 MPa时，尺寸效应可使峰值应力提高21.3%，而在3.0 MPa高围压下对峰值应力影响不显著；端部摩阻力在3.0 MPa围压下可使峰值应力提升约7.4%. 研究成果为深入理解粗粒料力学特性提供了有效的数值分析手段.
Abstract:To investigate the mechanical meso-mechanism and macroscopic response of coarse granular materials in rockfill dams, and to overcome the limitations of traditional continuum-based methods in simulating force chain evolution and particle breakage, a continuous-discontinuous deformation analysis method suitable for triaxial tests on coarse granular materials was developed. This method, based on the traditional discontinuous deformation analysis (DDA) framework, introduced a hybrid displacement mode to differentiate the mechanical responses of various blocks. Critical damping was employed to accelerate computational convergence, and a continuous-discontinuous simulation technique was proposed to characterize particle breakage. Through conventional triaxial numerical simulations, the deformation evolution, force chain development, particle breakage, and shear band formation during loading were analyzed, with particular emphasis on the effects of size and end friction. The results indicate that the simulation outcomes agree well with experimental data, reflecting both the macroscopic mechanical response and meso-mechanisms of coarse granular materials. The size effect leads to a 21.3% increase in peak stress under 0.4 MPa confining pressure, whereas its influence becomes negligible at 3.0 MPa. Under 3.0 MPa confining pressure, end friction contributes to an approximately 7.4% increase in peak stress. This study provides an effective numerical tool for further understanding the mechanical properties of coarse granular materials.
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图 5 DDA与室内三轴试验的偏应力-应变曲线对比
Figure 5. Comparison of deviatoric stress–strain curves between DDA and laboratory triaxial tests
图 9 粗粒料颗粒旋转角度演化过程
Figure 9. Evolution of particle rotation angles of coarse granular materials
图 10 不同围压下粗粒料力链演化过程
Figure 10. Evolution of force chains of coarse granular materials under varying confining pressure
图 12 不同围压下试样x方向位移云图
Figure 12. x-displacement of samples under varying confining pressure
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