摘要:
为避免用瑞利波检测混凝土时骨料对探测目标体的干扰,保证混凝土质量检测的可靠性,需要区分骨料异常信号和目标体异常信号,为此,对含骨料混凝土中的瑞利波传播特性展开了研究。通过建立细观结构的骨料随机模型,采用高阶交错网格有限差分法,研究骨料的随机性、形状、粒径和含量对瑞利波波场及频散曲线的影响,得到不同骨料参数下的瑞利波散射情况、能量衰减、畸变特性以及频散曲线特征。通过不同骨料混凝土模型正演数据,定量地了解到骨料引起的瑞利波波场与频散曲线的异常大小与影响范围。研究结果表明:骨料的随机性与含量会对直达瑞利波的衰减产生影响,骨料形状的差异对瑞利波波场的影响很小,骨料粒径的变化对波场影响较大,当粒径超过1/2主频波长时瑞利波会产生较强的散射,波形会产生畸变;对频散曲线而言,骨料的随机性、形状、粒径和含量的变化均不会引起频散曲线异常,因此,使用瑞利波法进行混凝土检测时,采用频散曲线对数据进行分析,可避免骨料对目标体的干扰。
Abstract:
To avoid aggregate interference on the detection target in concrete quality detection by Rayleigh waves, the abnormal signals from the aggregate and the target should be distinguished for high detection reliability. Hence, this study explored the propagation characteristics of Rayleigh waves in aggregate concrete. By building the mesostructural random aggregate models and employing the high-order staggered-grid finite difference scheme, this study examined the effects of the randomness, shape, size, and content of aggregate on the Rayleigh wave field and dispersion curves, thus obtaining the Rayleigh wave scattering, energy attenuation, distortion, and dispersion curve characteristics under different aggregate parameters. Based on the forward modeling data of different aggregate concrete models, this study quantitatively analyzed the sizes and influence ranges of aggregate-induced anomalies of the Rayleigh wave field and dispersion curves. The results are as follows. The randomness and content of aggregate could affect the energy attenuation of direct Rayleigh waves. The Rayleigh wave field was slightly influenced by the aggregate shape but significantly impacted by the aggregate size. When the aggregate size exceeded half of the dominant wavelength, Rayleigh waves would produce strong scattering, distorting its waveforms. In contrast, these aggregate parameters caused no anomalies in the dispersion curves. Therefore, data analysis using dispersion curves can avoid aggregate interference on the target in concrete quality detection by Rayleigh waves.
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