结构性砂土粒间胶结效应的二维数值分析

Two-dimensional numerical investigation on bonding effect between particles of structured sands

将理想胶结颗粒接触力学特性的测试结果引入到离散元胶结接触模型中,对结构性砂土粒间胶结效应进行离散元数值模拟。首先,胶结颗粒被理想化为两铝棒在指定部位形成胶结,通过一系列加载试验(拉伸、压缩、压剪)获得胶结铝棒在不同应力路径下的接触力学响应。随后,将测试结果提炼总结后引入到自行开发的二维离散元程序NS2D中,用以模拟不同初始密度和胶结强度的结构性砂土等向压缩试验。最后,通过与人工胶结砂土的试验数据进行比较,对文中的数值模拟结果进行验证。研究表明:离散元数值模拟能够有效的捕捉结构性砂土的主要力学特性,即屈服强度和体积模量均随初始密度和胶结强度的变化而变化,且胶结试样的屈服强度与试样内部颗粒间胶结点破坏率密切相关。

After capturing the contact behaviours of idealized bonded granules in the contact model of discrete element method（DEM）,the numerical investigation is carried out on bonding effect between particles of structured sands.First,the bonded granules are idealized by two aluminum rods glued together in a pre-defined model.The contact behaviours between the bonded rods are obtained by applying a set of mechanical tests.Secondly,a simple bond contact model is deduced from the measured results of the bonded rods and introduced in our two-dimensional DEM code（NS2D） to simulate a series of isotropic compression tests on the materials with different densities and bonding strengths.Finally,the DEM results are examined in comparison with the experimental data on artificially bonded sands obtained.The study shows that the DEM model is able to capture the main features of structured sands,such as variations of yielding and bulk modulus against the initial density or bonding strength.In addition,it is shown that the primary yielding is largely related to the bond breakage.