基于离散元的沥青混合料单轴压缩细观仿真分析

Microscopic Analysis of Asphalt Mixture under Uniaxial Compression Based on Discrete Element

为在细观层面探究单轴压缩过程对沥青混合料组成结构的影响,基于离散元理论,仿真模拟沥青混合料单轴压缩试验,分析沥青混合料应力-应变、空隙率、颗粒位移、裂隙发展,以及接触力的变化特征,验证了离散元模拟单轴压缩试验的先进性与可行性。结果表明,在单轴压缩试验过程中,试件空隙率先缓慢减小后迅速增大,经历从压实-裂缝产生并发展-破坏的阶段;试件颗粒位移方向与加载力的方向相同,加载过程中位移大小由试件两端向中间递减,且近似呈现对称分布,加载结束时颗粒位移分布呈现45°倾斜角;与颗粒位移对应,裂隙的产生也呈现由两端向中间发展的规律,最后形成X形裂纹带;单轴压缩过程中颗粒间接触力分布较为均匀,随着加载的进行,颗粒间接触力逐渐变得稀疏,进而导致抗压强度的降低。

In order to explore the influence of uniaxial compression process on the composition structure of asphalt mixture at the microscopic level,the uniaxial compression test of asphalt mixture was simulated based on three-dimensional discrete elements.The characteristics of stress-strain,voidage,particle displacement,crack development and contact force of asphalt mixture were analyzed,and the advancement and feasibility of the uniaxial compression test simulated by discrete elements were verified.The results show that in the uniaxial compression test,the void of the specimen decreases slowly first and then increases rapidly,and goes through the stage of compacting-crack generation and development-failure.The displacement direction of the specimen particles is the same as that of the loading force.During the loading process,the displacement size of the specimen decreases from the two ends to the middle,and the distribution of the particle displacement presents an approximate symmetrical distribution.At the end of the loading,the distribution of the particle displacement presents a 45°inclination angle.Corresponding to the displacement of particles,the crack generation also presents a law of development from two ends to the middle,and finally forms an X-type crack zone.In the uniaxial compression process,the contact force distribution between particles is relatively uniform,and with the progress of loading,the contact force between particles gradually becomes sparse,which leads to the reduction of compressive strength.