关键词: 混凝土, 声发射, 动态损伤, 循环加卸载, 混凝土单轴压缩试验

Abstract:

In order to study the dynamic damage features and damage evolution regularity of concrete, we carried out uniaxial compression test on concrete under different loading rates (10^-5/s,10^-4/s, 7.5×10^-3/s) and collected the real-time acoustic emission signals. By analysing the relationship between acoustic emission parameters and stress-strain, we obtained the plastic deformation and damage features of concrete under cyclic loading and unloading. Results reveal that the damage concentrates in the early and middle stages of the cyclic loading and unloading process.The damage intensifies with the increase of loading time and cycle numbers. Damage variable also increases along with the increase of accumulated residual plastic strain. Moreover, when loading rate increases, the energy release before the peak gets larger and damage path becomes shorter. When the difference between loading rates gets larger, the damage path difference becomes larger, but the start point and end point of damage curves overlap.

Key words: concrete, acoustic emission, dynamic damage, cyclic loading and unloading, uniaxial compression test on concrete