Experimental Study on Splitting Tensile Damage Characteristics and Discrete Element Simulation of Concrete Based on Acoustic Emission Technology

To study the splitting tensile damage characteristics of concrete, this paper conducted Brazilian disc split tensile tests on concrete and mortar with three water-cement ratios and four loading rates, respectively. Acoustic emission (AE) technology was used for real-time. The test results indicate that in the early loading stage of Brazilian disc specimens, a small number of microcracks are primarily generated at the interface between aggregate and mortar, and microcracks and macrocracks are generated simultaneously at the peak stress. The peak frequency characteristics of AE explain the strength enhancement principle and strain rate effect of concrete damage. The curves of AE cumulative ringing and AE energy counting reflect the internal damage activity of concrete and mortar specimens at different stress stages. Finally, a model that conforms to the macroscopic performance of the concrete dynamic splitting tensile test was established based on the discrete element method (DEM) and Hertz-Mindlin bond model. The simulation was compared with the actual analysis to verify the effectiveness of the parameters. The evolution of concrete damage space was studied through the discrete element simulation results, and the three evolution stages of damage space were summarized, which confirmed that the DEM plays an essential role in the field of micromechanics.