Verification of DEM for Granular Materials by Tests Using Aluminium Rods

DEM是一种通过模拟圆盘或块之间接触点的力学特性来模拟不连续体行为的方法。它可以分析颗粒状材料的行为，如沙子和不连续的岩石。为了得到合适的分析结果，通常需要确定颗粒间的弹性常数、黏度系数、摩擦系数等参数，以及颗粒大小等参数。利用圆棒间接触理论，尽可能准确地确定了铝棒间的弹性常数。提出了一种在棒材实际受力情况下测量棒材间摩擦系数的方法。采用准确参数的DEM模拟结果与等直径铝棒规则填料的直剪箱试验结果进行了比较。结果表明，该方法能较好地模拟铝棒在直接剪切作用下的受力行为。对于不同直径的铝棒的不规则包装将作类似的比较。对极轻填充材料EPS进行了室内模型试验，并与DEM和FEM分析结果进行了比较。通过比较，DEM比FEM更适合于解释EPS的不连续行为。

The DEM is a method for simulating the behaviour of a discontinuous body by modelling the mechanical properties at contact points between disks or blocks. It can analyze the behaviour of granular materials like sands and discontinuous rocks. The parameters between particles such as elastic constants, coefficients of viscosity and coefficients of friction, and the particle size are usually determined so as to obtain appropriate analytical results, The research results are summarized as follows :1. The elastic constants between aluminium rods were determined as accurately as possible by the contact theory between circular rods. A method for measuring frictional coefficients between rods under the real behaviour of rods was proposed.2. The simulation results by DEM using the accurate parameters was compared with the results of direct shear box tests on the regular packing of aluminium rods with equal diameter. It became clear from the comparison that the DEM can simulate the behaviour of aluminium rods under direct shearing exactly. A similar comparison will be made for the irregular packing of aluminium rods with different diameter.3. The model tests on EPS, a very light fill material, were carried out in the laboratory, and were compared with the analytical results by DEM and FEM. Based on the comparison, DEM is more suitable than FEM for explaining the discontinuous behaviour of EPS.