【摘要】 为探讨裂纹时空演化规律，基于改进的声发射源定位方法和矩张量理论，反演双边开口的混凝土试件压剪破坏过程中裂纹位置、裂纹类型以及裂纹面的法线方向和运动方向。分析结果表明，试件在拉应力损伤破坏区域，拉伸型裂纹扩展占主导，在剪应力损伤破坏区域，剪切型裂纹扩展占主导。矩张量分析中不同类型裂纹的时空分布特征与试件实际受力和损伤情况相一致，说明矩张量理论能够有效描述拉应力、剪切应力的分布和迁移规律，这为深入研究混凝土损伤演化机理提供了有力工具。从声发射信号波形和小波时频图可以看出：拉伸型裂纹对应的声发射信号持续时间约为800μs,频率范围是7～500 kHz;混合型裂纹和剪切型裂纹对应的声发射信号频率范围分别为7～500 kHz和7～250 kHz,持续时间相对较长，分别为1 720μs和1 880μs;剪切破裂要比拉伸破裂释放的能量多，同时剪切破裂释放的剪切波平均频率要比拉伸破裂释放的应力波平均频率低。更多还原

【Abstract】 The locations, types and orientations of cracks on concrete specimens with bilateral openings during the shear failure process under uniaxial compressive loading are inversed to study the temporal and spatial evolution law of cracks based on the improved acoustic emission localization method and the moment tensor theory. The results of moment tensor analysis show that the growth of tensile cracks is dominant in the tensile damage zone, and the growth of shear cracks is dominant in the shear damage zone, which are consistent with the conditions of actual stress and damage in the specimen. This indicates that the moment tensor theory is a useful method to further study the mechanism of damage evolution in concrete, as it can be used for describing the distribution and migration of tensile stress and shear stress effectively. The results of waveform analysis show that the duration of acoustic emission(AE) signal corresponding to tensile crack is about 800 μs, and the frequency range is 7-500 kHz. The AE signals associated with mixed-mode crack and shear crack have frequency ranges from 7 kHz to 500 kHz and from 7 kHz to 250 kHz, respectively, and have higher duration of about 1 720 μs and 1 880 μs, respectively. The main reason is that the energy released by shear rupture is higher than that by tensile rupture, and the average frequency of shear wave released by shear rupture is lower than that of stress wave released by tensile rupture.更多还原