基于声发射事件数的水工混凝土损伤率效应研究

Damage Rate Effect of Hydraulic Concrete Based on Acoustic Emission Parameters

为研究加载速率对水工混凝土损伤演化特性的影响,对两种尺寸的带缺口水工混凝土立方体试件(边长为300、450 mm)进行不同加载速率(0.1、0.01、0.001 mm/s)下楔入劈拉试验,并采用声发射技术监测混凝土在破坏过程中的声发射信号。结果表明,在混凝土破坏过程中声发射事件率的变化可分为平静期、活跃期和衰减期,且随加载速率降低,活跃期增长。根据声发射事件数定义的损伤变量将水工混凝土的损伤过程分为裂缝萌生阶段、裂缝加速扩展阶段和破坏阶段三个阶段。加载速率越小,损伤第二阶段增长速率越快。基于声发射事件数建立的损伤演化模型服从Weibull分布,该模型能较好地反映混凝土在不同加载速率下的损伤演化特征。

In order to study the influence of loading rate on the damage evolution of hydraulic concrete,notched cubic specimens with side lengths of 300 mm and 450 mm were tested by wedge splitting test with different loading rates of 0.1 mm/s,0.01 mm/s,0.001 mm/s.Acoustic emission technology was used to monitor the acoustic emission signals of concrete in the damage process.Test results show that the variation of AE event rate during failure process of concrete can be divided into quiet,active,and attenuation period,among these the active period increases with the decrease of loading rate.The damage was defined according to the AE events,and it is found that the damage process of hydraulic concrete can be divided into three stages:crack initiation,acceleration and failure.The smaller the loading rate is,the faster the growth rate of the acceleration stage is.The damage evolution model based on the AE event obeys Weibull distribution,which can better reflect the influence of loading rates on the damage evolution of hydraulic concrete.