基于声发射参数的不同级配混凝土动态劈拉试验研究

Dynamic Splitting Test Based on Acoustic Emission Parameters of Different Graded Concrete

对不同级配(二级配、三级配、四级配)的混凝土在不同应变速率下(10-5/s,10-4/s,10-3/s,10-2/s)下进行了劈拉试验。对混凝土劈拉强度及轴向应变进行了深入分析,并利用实时采集的声发射数据分析了大体积混凝土在劈拉破坏全过程中的能量释放特性及破坏规律。结果表明:随应变速率的增加混凝土劈拉强度呈增加的趋势,混凝土级配越高劈拉强度变化的奇异性越大;混凝土劈裂抗拉破坏过程不具有典型未裂阶段、裂缝阶段和破坏阶段的3阶段特征,加载前期产生的声发射信号较微弱,材料达到峰值应力时能量信号突然急剧上升;采集的声发射数据能较真实地反映混凝土劈拉破坏全过程。

Splitting tensile tests were conducted on concrete with different gradations （two gradations,three grada-tions,and four gradations）under different strain rates （10-5 /s,10-4 /s,10-3 /s,10-2 /s）.The splitting tensile strength and axial strain of concrete were analyzed,and the energy release characteristics and damage regularity of mass concrete in the whole process of splitting tensile damage were researched through collected real-time acoustic emission data.Results show that with the strain rate increasing,the splitting tensile strength of concrete displays a trend of increasing.Singularity in the variation of splitting tensile strength is larger when the gradation of concrete is higher.The process of splitting tensile failure does not have the characteristics of a typical three-stage：stage without cracks,stage with cracks,and stage of failure.The acoustic emission signal is weak in the early stage of loading, but rises sharply when the material reaches peak stress.Acoustic emission data can truly reflect the process of con-crete splitting tensile failure.