圆锥指数仪贯入沙土过程的三维离散元法模拟

在圆锥指数仪贯入沙土试验的基础上,建立了半圆柱形沙土料床的三维数值模型,利用离散元法对圆锥指数仪贯入沙土过程进行了模拟,讨论了圆锥指数的主要影响因素及其影响规律。研究结果表明:贯入圆锥的铅垂方向阻力、圆锥指数及半圆柱形料床侧壁的正压力均随着贯入深度的增加而增大,且形状窄、粒径大的料床圆锥指数明显大于形状宽、粒径小的料床;贯入后的大颗粒料床侧壁正压力明显大于小颗粒料床;当圆锥贯入速度大于0.2 m/s时,圆锥指数才明显增大,此时贯入过程已经对料床产生较强的冲击效应。最后,把贯入后的料床根据颗粒的位移划分为4个区域,可以直观地判断出贯入过程的影响范围,为实地测量土壤坚实度时取样点间距的选取提供了理论依据。

3D DEM Simulations of the Cone Penetration Tests in Sandy Soil

Based on the experiments of the sandy soil penetration, a semi-cylindrical sandy soil bed in 3D was established, and the simulation with discrete element method for the penetration was investigated. According to the studies on the experiments and simulations, the analysis of influencing factors to the cone index of soil was discussed. And the result showed that the vertical resistance of the penetrometer, cone index and the normal force on the semi-cylindrical wall all increased as the increasing of the penetration depth. And the cone indexes of the narrow and big particle soil bed are much larger than the wide and small particle beds. Besides, the normal force on the semi-cylindrical wall of the big particle bed after penetration is larger than the small particle one. Only after the penetration velocity exceeded 0.2m/s would cone index increase obviously because of impact force from the penetrometer on the particle bed. Finally, according to the displacement of particles, the particle bed after penetration was divided into four zones, and the influencing area could be defined easily, which provided theoretical foundation for determination of distance between measurement points in situ test of soil compaction.