基于颗粒流法研究混凝土的劈裂拉伸破坏特性

Based on the two-dimensional particle flow program, a two-dimensional concrete mesoscopic model was established including cement mortar, irregular polygonal aggregate and the interface (ITZ) between cement mortar and aggregate. The crack evolution and failure mechanism of fracture concrete was investigated using the calibrated flat joint model parameters. The simulation results indicate that the meso-mechanism of the macroscopic failure is induced by the crack propagation and evolution in the cement mortar, aggregate and ITZ. In addition, the distribution of random aggregates has an impact on the peak stress and failure mode of concrete at a certain level. The crack in the Brazilian disc specimen is generated at the loading end, and expands to the center of the specimen as the load increases. Finally, a split tensile failure mode appears in the concrete specimen. Moreover, as the loading speed increases, a large number of fragments in the concrete specimen are generated due to the interaction between the main cracks along the loading direction and other secondary cracks. The statistical results of cracks indicate that tensile cracks dominate the split failure of concrete specimens at the mesoscopic level. At the same time, a few shear cracks are mainly generated near the aggregate at the loading end of the specimen.