单轴加载下混凝土超声波与声发射联合特性试验研究

Experimental study on characteristics of acoustic emission with ultrasonic wave of concrete under uniaxial multilevel loadings

本研究通过混凝土试件在单轴向受压下的试验研究,对比了不同强度等级立方体和棱柱体试件对超声波波速的影响,分析超声波及声发射参数随应力的变化关系。试验结果表明:强度等级越高的混凝土超声波波速时间稳定性表现越好;棱柱体超声波稳定性优于立方体试件;在工作应力为极限破坏应力的20%~70%阶段,超声波波速下降缓慢,声发射撞击数增加,能量和振铃计数呈突发式增长;当工作应力大于混凝土的极限破坏应力70%后,超声波波速明显下降,声发射活动急剧增加。提出划分应力阶段对2种检测方法进行分析,为混凝土结构工作应力状态的检测提供参考。

This paper investigates the variation of ultrasonic wave velocity for concrete cubes and concrete prisms of different strength under uniaxial multilevel loadings of compressive stress by experimental method. Along with the change of the stress, the ultrasonic and acoustic emission parameters were analyzed. The testing results showed that the influence of the variation of ultrasonic wave velocity was less for high strength concrete than low stress strength. The relation of the concrete prism work stress and the ultrasonic wave velocity was better than that of the concrete cubes. When the work stress was in the range of 20%-70% of the ultimate failure strength of concrete, the ultrasonic wave velocity decreased slowly, the burst growth of energy and ringing counts with acoustic emission hits increased. When the work stress was larger than 70 % of the ultimate failure strength of concrete, the ultrasonic velocity decreased obviously, and the acoustic emission activity increased dramatically. We proposed dividing stress stages for analyzing two detection methods. The research provides a reference for detection of concrete structure under work stress.