基于声发射技术的混凝土动态损伤特性研究

Dynamic Damage Features of Concrete Based on Acoustic Emission Technology

为研究混凝土材料动态损伤特性及损伤演化规律,进行了不同加载应变速率下(10-5/s,10-4/s,7.5×10-3/s)的混凝土单轴压缩试验,并实时采集相应的声发射信号;在分析声发射参数与应力应变关系的基础上研究了在循环加卸载条件下混凝土材料的塑性变形特性及损伤特性。结果表明:循环加卸载过程中损伤集中在前期和中期,损伤程度随加载时间的延长逐渐加重,循环次数越多,损伤越严重;随着累积残余塑性应变的增加,损伤变量逐渐增大,加载应变速率越大,峰值前的释放能量越大,混凝土破坏越严重;随加载应变速率的提高,损伤破坏的路径变短,加载应变速率差异越大,损伤破坏路径差异越大,但损伤变化曲线起点与破坏终点重合。

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 collect- ed 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 unloa- ding. 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 increa- ses along with the increase of accumulated residual plastic strain. Moreover, when loading rate increases, the ener- gy 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