颗粒形状对不良级配碎石集料剪切特性的影响

发布时间：2018-05-01 17:13

本文选题：颗粒形状 + 剪切特性　；参考：《岩土力学》2017年08期

【摘要】：碎石颗粒的形状对于集料的整体剪切性能有很大的影响,而现有的研究缺乏对于不规则块体颗粒形状的定量评价指标。利用离散元软件PFC2D(Particle flow code,2D)研究,提出了不规则块体的生成方法,建立了平面双轴剪切试验条件,通过对比室内试验结果完成了对模型的验证以及细观参数的选择。通过对块体进行分割后得到的多边形相邻顶角的差值进行分析,改进了棱角度指数的概念,在此基础上分析了颗粒形状对于级配不良的碎石集料的力学性质的影响,研究结果表明:棱角度指数受划分边界数的影响较大,随着划分密度的增加,棱角度指数不断减小并趋于稳定;随着轴向应变的增加,碎石集料的剪应力呈现出明显的非线性增加,曲线的形态受颗粒形状影响较大,除球形颗粒外,其他形状颗粒集料均呈现出应变硬化的特性。在棱角度指数较低时,抗剪强度和内摩擦角缓慢增加,而当棱角度较大时,抗剪强度指标则增加较快,可以通过幂函数进行拟合。
[Abstract]:The shape of gravel particle has a great influence on the overall shear performance of aggregate, but the existing research lacks quantitative evaluation index for the shape of irregular block particle. Based on the study of discrete element software PFC2D(Particle flow code2D, an irregular block generation method is proposed, and the plane biaxial shear test conditions are established. The model verification and the selection of mesoscopic parameters are completed by comparing the results of laboratory tests. By analyzing the difference of adjacent vertex angle of polygon after block segmentation, the concept of angle index is improved, and the influence of particle shape on mechanical properties of broken stone aggregate with poor gradation is analyzed. The results show that the prism exponent is greatly affected by the number of partition boundaries. With the increase of partition density, the angularity index decreases and tends to be stable, and with the increase of axial strain, The shear stress of crushed stone aggregate showed an obvious nonlinear increase, and the shape of the curve was greatly affected by the shape of the particle. Except for the spherical particle, all the other shaped aggregates showed the characteristics of strain hardening. When the angle index is low, the shear strength and the angle of internal friction increase slowly, but when the angle is large, the index of shear strength increases faster, which can be fitted by power function.
【作者单位】：北京交通大学土木建筑工程学院;中国铁道科学研究院铁道建筑研究所;
【基金】：国家自然科学基金(No.41371081,No.51378057)~~
【分类号】：U414

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