基于GMM的湿筛混凝土轴拉损伤演化机制研究

Study on axial tensile damage evolution mechanism of wet-screenedconcrete based on GMM

为研究不同加载阶段下的二级配湿筛混凝土开裂模式与损伤演化过程,将声发射技术(AE)与高斯混合模型(GMM)进行结合作为损伤识别手段,以3种加载速率(1×10^(-6)、5×10^(-6)、25×10^(-6)s^(-1))作为试验变量,对二级配湿筛混凝土开展单轴拉伸损伤时空演化机制试验研究。结果表明:随着加载速率增大,湿筛混凝土试件内部裂缝开展更加密集,并且裂缝种类随机性更高;利用GMM法对声发射数据进行处理分类结果显示,拉伸裂缝为试验加载过程的主要开裂模式,加载速率升高会导致剪切裂缝占比增大;随着加载速率增大,拉伸裂缝频率分布明显扩大,而剪切裂缝与混合裂缝频率分布基本不变;随着加载进行,拉伸裂缝与剪切裂缝概率密度区域均向AF轴趋近;GMM法所得裂缝开裂模式有拉伸裂缝、剪切裂缝与混合裂缝3种类别,并且随着加载进行,混合断裂区所处位置也会发生变化;相较于常规裂缝模式分类方法,GMM法提供了更好的裂缝分类近似值分析,对裂缝开裂模式表述更加可靠。

In order to study the cracking mode and damage evolution process of two-stage wet-screened concrete under different loading stages,acoustic emission(AE)and Gaussian mixture model(GMM)were used as damage identification methods.Three loading rates(1×10^(-6),5×10^(-6),25×10^(-6)s^(-)1)were used as test variables to carry out the experimental study on the spatiotemporal evolution mechanism of uniaxial tensile damage of two-stage wetscreened concrete.The results show that with the increase of loading rate,the internal crack development of wetscreened concrete specimens is more intensive,and the randomness of crack types is higher.After the GMM method being used to process and classify the acoustic emission data,the tensile cracks are the main cracking mode in the test loading process,and the increase of loading rate will lead to the increase of shear cracks.With the increase of loading rate,the frequency distribution of tensile cracks is significantly expanded,while the frequency distribution of shear cracks and mixed cracks is basically unchanged.With the loading process,the probability density regions of tensile cracks and shear cracks tend to the AF axis.The crack mode obtained by GMM method includes the following three categories:tensile crack,shear crack and mixed crack.With the loading process,the location of mixed fracture zone will also change.Compared with the conventional crack pattern classification method,GMM method provides better approximate value analysis of crack classification and more reliable expression of crack cracking pattern.