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转动阻抗被定义为作用颗粒接触上的一对对称力偶,用来抵抗颗粒之间的相互转动。将转动阻抗引入到离散元模拟中是对传统离散单元法的重要改进。开发出考虑颗粒转动阻抗的接触模型,并将其嵌入到PFC2D中,利用该模型进行粗粒土的双轴剪切数值模型试验,研究剪切过程中转动阻抗对粗粒土的宏细观力学性质的影响。结果显示,在宏观方面,颗粒转动阻抗对粗粒土的宏观力学行为(应力-应变及体应变-轴应变行为)有重要的影响,随着转动阻抗的增加,粗粒土的剪切强度和最大摩擦角随之增加,这与已有的研究结果一致,证明所建模型是可靠的;在微观方面,考察转动阻抗对粗粒土内部微观结构的影响发现,随着转动阻抗的增加,粗粒土的内部的接触数目减少,而粗粒土的剪切强度增加,表明转动阻抗能够提高粗粒土力链网络的稳定性,同时发现随着转动阻抗的增加,粗粒土的各向异性增加主要是强力链各向异性的增加,说明转动阻抗增强了强力链的传递力的能力以及抵抗力链屈曲破坏能力。数值模拟结果表明,增加颗粒转动阻抗,粗粒土出现组构与轴应变非共轴的现象。
Rotational impedance is defined as a pair of symmetrical couple on the contact of the active particles to resist mutual rotation between the particles. The introduction of rotational impedances into discrete-element simulations is an important improvement over the traditional discrete-element method. A contact model considering particle rotational resistance was developed and embedded in PFC2D. The biaxial shear numerical model test of coarse grained soil was carried out with this model to study the influence of rotational impedance on the macro-meso-mechanics of coarse grained soil The nature of the impact. The results show that in the macroscopic aspect, the rotation resistance of particles has an important influence on the macroscopic mechanical behavior (stress-strain and bulk strain-axial strain behavior) of coarse grained soil. With the increase of rotation resistance, the shear strength of coarse grained soil The maximum friction angle increases, which is in agreement with the existing research results, which proves that the model is reliable. Microscopically, the influence of rotational impedance on the microstructure of coarse grained soil is investigated. With the increase of rotational resistance, The decrease of the internal contact of the soil and the increase of the shear strength of the coarse-grained soil indicate that the rotation resistance can improve the stability of the coarse-grained soil-strength chain network. At the same time, it is found that with the increase of the rotation resistance, the anisotropy of the coarse-grained soil The increase is mainly due to the increase of anisotropy of the strong chain, indicating that the rotation resistance enhances the transmission ability of the strong chain and the buckling damage ability of the resistance chain. The results of numerical simulation show that when the rotational impedance of particles is increased, the phenomenon of non-coaxial structure and axial strain appears in the coarse grained soil.