粗粒土应力诱发各向异性真三轴试验颗粒流模拟研究

发布时间：2018-01-11 04:27

本文关键词：粗粒土应力诱发各向异性真三轴试验颗粒流模拟研究　出处：《岩土工程学报》2015年12期 　论文类型：期刊论文

【摘要】：基于颗粒流基本理论和物理试验结果,通过改进PFC3D程序中的内置代码,生成包含clump颗粒的混合试样以克服纯球体颗粒模拟粗粒土抗剪强度不足的缺陷,模拟粗粒土在真三轴状态下各主应力方向上的单向加荷试验,并从宏观和细观角度分析了复杂应力状态下粗粒土的应力诱发各向异性特征。试验结果显示:复杂应力状态对各向异性的诱发作用显著,各向宏、细观参数及应力应变曲线显示出了显著的各向异性;单向加荷试验中加荷向始终为压缩变形,侧向变形复杂,且受初始中主应力系数B影响显著,且B值对非加载向泊松比的各向异性及加载向应力应变曲线的影响亦较明显;模拟试验中配位数、孔隙率等细观参数的变化趋势能够反映试样体积变形的类型,两个细观参数的取值大小影响抗剪强度的强弱,并且各主应力方向单向加荷时,对应相同的应力增量配位数、孔隙率等细观参数表现出显著的各向异性;从细观角度看,应力诱发各向异性产生的原因归结于侧向围压差异所引起的细观结构变化。
[Abstract]:Based on the basic theory of particle flow and the results of physical experiments, the built-in code in PFC3D program is improved. A mixed sample containing clump particles was formed to overcome the defects of pure spherical particles in simulating the insufficient shear strength of coarse grained soil and to simulate the unidirectional loading test of coarse grained soil in each direction of principal stress under true triaxial state. The characteristics of stress-induced anisotropy of coarse-grained soil under complex stress state are analyzed from macroscopic and meso perspectives. The experimental results show that complex stress state can induce anisotropy obviously and every direction is macroscopical. The meso-parameters and stress-strain curves show remarkable anisotropy. In the unidirectional loading test, the loading direction is always compression deformation, the lateral deformation is complicated, and is significantly affected by the initial principal stress coefficient B. The effect of B value on the anisotropy of the unloaded Poisson's ratio and the stress-strain curve in the loading direction is also obvious. The variation trend of coordination number, porosity and other meso-parameters can reflect the type of specimen volume deformation, and the value of two meso-parameters affects the strength of shear strength. And when each principal stress direction is loaded unidirectionally, the meso-parameters such as the same stress increment coordination number and porosity show remarkable anisotropy. From a meso point of view, the causes of stress-induced anisotropy are attributed to the variation of meso-structure caused by lateral confining pressure differences.
【作者单位】：新疆农业大学水利与土木工程学院;
【基金】：新疆维吾尔自治区自然科学基金面上项目(2013211A027)
【分类号】：TU43
【正文快照】： 0引言粗粒土作为一种非连续摩擦型工程材料,在工程中有着广泛的应用。它不仅在实践过程中表现出了压硬性、剪胀性、非线性非弹性、应力应变与应力路径和应力历史相关等诸多特性,还特别表出了各向异性特性[1]。然而,目前对于粗粒土力学特性的研究仍然以常规三轴试验为主,通过

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