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Developing study of detecting method for defective part on concrete structure by using laser vibrometer.

激光测振仪检测混凝土结构缺陷部位方法的研究进展

基本信息

批准号：
12555162
负责人：
IWASE Teruo
金额：
$ 6.78万
依托单位：
NIIGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Vibration techniques were examined for detecting of crack or exfoliation part came put on a concrete structure.At first, some kinds of concrete test block with the groove of depth as 10mm-40mm were made for imitating cracks.Next, two kinds the concrete test block with exfoliation of thickness as 20mm were made. By using these test blocks, many analyzes of vibration response on the all area, especially around defective part, were carried out.As the result of these analyzes, it was found that piezoelectric buzzer device was effective for the excitation of vibration in wide frequency range.It was also found that laser vibrometer was useful for the observation of vibration, because it made easy positional moving and it had sensitivity in very high frequency range.As for detecting of parts of exfoliation, detecting was easy, because there was strong vibration response on such area compared with the sound part in the audio frequency range. As for detecting of crack, the amplitude of vibration response became weak over the groove in the supersonic frequency range. More than 20mm depth of the groove, phase delay in the supersonic frequency range appeared large changes as several ten thousand degrees between both sides of the test groove.For the practical detecting technique, pressing down type to the test surface and movable type device for vibration excitation is useful, and dual channel receiving technique for vibration by laser vibrometer was effective to obtain stable analyzed results.These techniques were also confirmed to the actual wall surface, and then effective results could be obtained for detection of the crack.By only these analyzing techniques in this stage, quantity of the crack depth could not be recognized clearly. So, another sound resonance method tried. Then, prospect of the quantitative detection of crack could be seen.

研究了混凝土结构开裂或剥落部位的振动检测技术。首先，制作了几种槽深为10mm ~ 40mm的混凝土试块模拟裂缝。然后制作两种剥离厚度为20mm的混凝土试块。利用这些试验块，对结构各部位，特别是缺陷部位周围的振动响应进行了分析。分析结果表明，压电蜂鸣器在较宽的频率范围内对振动的激励是有效的。激光测振仪的位置移动方便，在高频范围内灵敏度高，是测量振动的有效方法。对于脱落部位的检测，相对于音频范围内的声音部分，该部位的振动响应较强，检测比较容易。对于裂纹的检测，在超声速范围内，振动响应幅值在沟槽上方变弱。在凹槽深度超过20mm时，在超音速频率范围内，相位延迟在测试凹槽两侧之间出现了几万度的大变化。在实际检测技术中，采用压下式和移动式振动激励装置，采用激光测振仪双通道振动接收技术，可获得稳定的分析结果。这些技术也在实际壁面上得到了验证，从而得到了有效的裂缝检测结果。在此阶段，仅通过这些分析技术，还不能清楚地识别裂纹深度的数量。所以，尝试了另一种声音共振方法。展望了裂纹定量检测的发展前景。