天然岩土在受荷过程中会经历不同的应力路径,应力路径相关性是岩土材料的一项基本特性。目前尚无明确研究证实离散元颗粒集合也同样具备应力路径相关性,在一定程度上影响了用离散元方法模拟天然岩土的可靠性。针对这一问题,采用PFC2D离散元软件搭建具有粒间胶结效应的颗粒集合,通过自定义Fish语言开发出能模拟不同应力路径的双轴压缩程序,对离散元颗粒集合进行了多组双轴压缩试验模拟。试验结果表明:离散元颗粒集合同样具有应力路径相关性。在相同颗粒黏结强度及不同初始围压的条件下,围压变小的应力路径比围压不变的应力路径使离散元颗粒集合达到的峰值强度更小。在不同应力路径影响下,离散元颗粒集合在强度特性、破坏特性上都表现出一定的差异性,其结果与真实岩土材料的室内试验结果相似,说明离散元颗粒集合同样具备应力路径相关性,可用来模拟天然岩土材料。

The correlation of stress paths in natural rock and soil during loading is a basic characteristic of rock and soil material. At present, there is no clear study proving that the discrete element particle set also has stress path correlation, which impairs the reliability of simulating natural rock and soil using discrete element method. In view of this, we construct a set of particles with intergranular cementation in the PFC2D particle discrete element software and further simulate many groups of dual-axial compression test on the discrete element particle sets by a self-developed program which could simulate different stress paths through a customized Fish language. The simulation results suggest that discrete element particle sets are also of stress path correlation. In the condition of the same bonding strength between particles and under the same confining pressure, the peak strength of particle sets induced by stress path of declining confining pressure is smaller than that by unchanged confining pressure. Under the influence of different stress paths, the discrete element particle sets vary in strength characteristics and failure characteristics, which is similar to those of real rock materials, indicating that discrete element particles can be used to simulate natural geotechnical materials.