不同厚度及边界胶结颗粒抗压特性离散元分析

DEM Analyses on Effects of Bond Thickness and Boundary Condition on the Compressive Response of Bonded Granules

为研究胶结厚度和边界条件对胶结颗粒抗压特性的影响,利用离散元数值方法模拟了胶结颗粒的室内微观压缩试验,并与室内试验结果进行了对比。结果表明,胶结厚度对胶结颗粒抗压强度影响较大,抗压强度随胶结厚度的增加呈指数形式下降并趋近恒定值,这一现象与室内试验结果吻合较好。而胶结厚度的影响程度与边界约束有关,当边界约束较强时微观剪切破坏占主导,抗压强度较高。另外,边界形状对微观胶结破坏模式(拉伸破坏或剪切破坏)有一定影响,平面边界由于边界约束效应更强,导致胶结颗粒的抗压强度更高。

In order to study the effects of the bond thickness and boundary conditions on the compressive resistance of bonded granules,the compression test of a pair of bonded granules is simulated using the distinct element method（DEM） in comparison with the micro mechanical test conducted in the laboratory. The results demonstrate that the compressive strength of the bonded granules is exponentially reduced to a steady value with the increase of the bond thickness,which coincides with the laboratory test results. The thickness effect is strongly affected by the confinement of boundary. In the case of strong confinement,the shear failure is dominant over the tensile failure in the failure mode of microscopic structure of the bond,leading to a higher compressive strength. In addition,the geometry of the boundary affects the microscopic failure mode to some extent. Providing a stronger confinement,a flat boundary results in a higher compressive strength of the sample compared with that in case of a curved boundary.