钢筋混凝土板声发射波传播特性试验研究

为了研究钢筋混凝土板的材料和结构参数对声发射关键参数的影响规律,设计制作了9个板试件,并进行了断铅试验和声发射测试。利用自制断铅装置进行断铅试验,确定了适用于钢筋混凝土板的门槛值和峰值鉴别时间等声发射检测参数的设置方法。通过断铅试验和声发射测试,研究了混凝土龄期、板厚、混凝土强度等级、粗骨料最大粒径和配筋等参数对声发射波速和振幅衰减的影响规律。结果表明,板厚和混凝土强度等级是影响声发射波速和振幅衰减的重要因素。波速随着混凝土板厚的增加而减小,随着混凝土强度等级的提高而增大;而板厚越大,混凝土强度等级越低,振幅的衰减越大。骨料最大粒径和配筋对声发射波速和振幅衰减影响较小。此外,还给出了振幅衰减值与传播距离的关系式,以及振幅衰减限值的建议值。

Tests for AE wave propagation characteristics in RC slabs

To study influences of material and structural parameters of RC slabs on wave velocity and amplitude attenuation of acoustic emission(AE),pencil lead breaks(PLB)and AE tests of 9 RC slab specimens were conducted.Using a self-made PLB device for PLB tests,the AE detecting parameters including threshold,peak identification time,identification of impact time,and impact locking time being applicable to RC slabs were determined.Through PLB and AE tests,the influence laws of RC age,thickness,concrete strength grade,coarse aggregate maximum particle size and reinforcement on AE wave velocity and amplitude attenuation were studied.The results showed that thickness and concrete strength grade are important factors to affect AE wave velocity and amplitude attenuation;AE wave velocity decreases with increase in concrete thickness,and it increases with increase in concrete strength grade;the larger the thickness and the lower the concrete strength grade,the bigger the amplitude attenuation;coarse aggregate maximum particle size and reinforcement ratio affect AE amplitude attenuation and wave velocity more weakly;the relation expression between amplitude attenuation value and propagation distance is derived,and the threshold value for amplitude attenuation is recommended.