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基于离散元软件PFC3D,通过编制可破碎的颗粒簇单元,模拟三轴试验中不同高径比试样应力应变特性的差异,通过比较强度和变形参数差异探讨适合粗粒土的高径比。研究结果表明:高径比越小,试验得到的内摩擦角越大,围压越大,由于颗粒破碎导致的内摩擦角越小;满足莫尔-库仑准则破坏面的最小高径比随着围压的增加而减小,但都大于现在室内试验常用的高径比;峰值强度随着高径比的增加而减小,随着围压的增大,不同高径比之间峰值强度相对误差减小;割线模量与高径比呈折线形关系;不同高径比之间割线模量的差异随高径比范围的不同而不同,且最小高径比的割线模量与现在室内试验常用高径比的割线模量在低围压下差异较大。依据模拟结果,认为粗粒土的三轴试样高径比应大于2.5。
Based on the discrete element software PFC3D, the difference of stress-strain characteristics of different height-diameter ratio specimens in three-axis test was simulated through the preparation of crushable particle cluster units. The aspect ratio suitable for coarse-grained soil was discussed by comparing the difference of strength and deformation parameters. The results show that the smaller the height-diameter ratio is, the larger the internal friction angle is and the larger the confining pressure is, the smaller the internal friction angle due to particle crushing is. The minimum height-diameter ratio of the failure surface satisfying the Mohr-Coulomb criterion The confining pressure increases but decreases, but both are larger than those commonly used in indoor tests. The peak intensity decreases with the increase of the aspect ratio. As the confining pressure increases, the peak intensities of different height-diameter ratios The error is smaller; the secant modulus is in the form of a line with the height-diameter ratio; the difference of the secant modulus between the different height-diameter ratios is different with the range of the height-to-diameter ratio and the secant modulus Now indoor test commonly used aspect ratio of the secant modulus at low confining pressure vary greatly. According to the simulation results, it is considered that the triaxial specimen height-diameter ratio of coarse-grained soil should be greater than 2.5.