用于离散元分析的胶结材料三维微观接触模型

岩石、结构性土、含水合物深海沉积土(能源土)等岩土材料均可视为由颗粒骨架和粒间胶结物共同构成的胶结型材料。简单实用的微观粒间接触模型是采用离散元数值方法分析胶结体系宏微观力学特性的基础。针对有一定厚度的粒间胶结形式,将胶结物简化为存在于颗粒之间有一定厚度的短圆柱。通过对胶结物内部应力分布进行适当简化推导了三维粒间接触模型,包括法向、切向、弯曲和扭转四个方向的相互作用规律。最终所得模型结合了理论推导和既有室内胶结接触力学试验成果,考虑粒间胶结物的法向压碎过程,能描述切向、弯曲和扭转单独作用的破坏过程以及剪弯扭共同作用下的破坏准则。模型形式简单,易于引入离散元程序。

Three-dimensional Microscopic Contact Model for DEM Analyses of Bonded Assembly

Geomaterials including rock, structured soil and methane hydrate bearing sediment can be envisioned as cemented assemblies composed of particle skeleton and interparticle bonds. A simple but efficient microscopic bond contact model is demanded for Discrete Element Method (DEM) analyses of the micro-and macro-properties of these geomaterials. The interparticle bond is treated as a short cylinder existing at the gap of two adjacent particles. The internal stress distributions in a bond are simplified to develop a bond contact model that incorporates interactions in the normal, tangential, rolling and twisting directions. With combination of the theoretical analyses and laboratory experimental results, the novel contact model can capture the bond breaking process due to compression in the normal direction. The failure criteria purely due to the tangential, rolling and twisting interactions are developed respectively, and a combined tangential-rolling-twisting failure criterion is proposed. The simple formulas in the novel contact model facilitate its implement in a DEM code.