不同含水率混凝土断裂过程声发射试验研究

为研究不同含水率混凝土断裂过程的差异性,将干燥试件浸泡不同时间,使其达到不同含水率,基于声发射技术,对三点弯曲梁的破坏过程进行监测。通过比较声发射信号撞击计数、能量计数和振铃计数等不同发射信号来反映不同含水率对混凝土断裂过程力学性能的影响规律,并结合撞击计数、振铃计数和能量计数捕捉起裂荷载,进一步分析水分对起裂韧度和失稳韧度的影响。试验结果表明,相比于P-CMOD曲线,声发射参数变化能更加直观地分析水分对混凝土断裂过程的影响。随着含水率的增加,起裂前,撞击计数累计值呈现增大趋势,起裂后,声发射参数值、峰值以及累计值均呈现减小趋势；损伤演化起始门槛值随含水率的增大而降低,饱和试件较干燥试件最大下降64%；饱和试件断裂过程区宽度较干燥试件最大增大20.8%；

Experimental Study on Influence of Different Moisture Contents on Fracture Acoustic Emission Characteristics of Concrete

In order to study the difference of fracture process of concrete with different moisture content, the dry specimen was soaked for different time to reach different moisture content. The failure process of three-point bending beam was monitored by acoustic emission technique.By comparing the difference of acoustic emission signals, such as hit,count and energy ,to reflect the different effects of different moisture content on the mechanical behavior of concrete fracture process, and combined with the hit, count and energy to catch up the initial fracture load, further analysis influences of the initial fracture toughness and unstable fracture toughness on different moisture contents. The experimental results show that the variation law of acoustic emission parameters can more intuitively analyze the influence of moisture content on the fracture process of concrete compared with the P-CMOD curve. As moisture content increased, before initiation fracture, the accumulative value of hit increases, however after initiation fracture, the values of acoustic emission parameters of peaks and accumulative values all decrease .The threshold value of damage evolution decreased with the increase of moisture content, and the maximum was decreased by 64% at saturated content from the value in completely dry condition.The width of the fracture process zone of the saturated specimen increased by 20.8% compared with the dried specimen.