非线性冲击共振声谱法检测混凝土损伤

DETECTION OF CONCRETE DAMAGE USING NONLINEAR IMPACT RESONANCE ACOUSTIC SPECTROSCOPY

非线性冲击共振声谱法(NIRAS)通过测量与损伤密切相关的材料非线性损伤参数,检测混凝土结构内部损伤。介绍NIRAS法的基本原理和试验系统,对使用4种水灰比配比的混凝土在单轴受压试验下的损伤进行检测,比较线性参数和非线性参数对损伤的灵敏度,讨论混凝土水灰比和损伤状态对材料非线性的影响。结果表明:损伤越大,非线性参数越大;水灰比越大,由于材料的初始固有缺陷引起的初始非线性参数越小,由受压损伤引起的非线性参数增速越大。试验证实NIRAS法可有效地应用于混凝土无损检测中,相较于传统线性无损检测方法灵敏度能提高一个数量级。

In order to effectively detect concrete damage,an established nonlinear acoustic technique-nonlinear impact resonance acoustic spectroscopy（ NIRAS） was used to experimentally determine the nonlinear parameter which was highly sensitive to the development of damage in concrete. The basic principles and experimental system of NIRAS technique were introduced. The NIRAS technique was applied to detect damage of concretes mixed with four different water-cement ratios subjected to uniaxial compression tests. The nonlinearity parameter defined in the NIRAS technique clearly had a much higher sensitivity to the microcracking development in these concrete samples as compared to the linear parameter defined in conventional techniques. The results showed that the nonlinearity parameter increased with the increased damage. The intrinsic nonlinearity due to initial defects in materials was reduced with increased water-cement ratio and the growth rate of subsequent nonlinearity due to compression damage increases with increased water-cement ratio. The finding proved that the developed NIRAS technique could be an effective tool for nondestructive detection of concrete.