This paper considers the applicability of remote laser sensing to reinforced concrete tunnel linings with suspected corrosion of the reinforced steel. As an alternative to the hammering test, this approach represents a non-contact inspection method that provides quantitative evaluation. Remote laser sensing uses two types of lasers: an impact laser to induce vibrations in the measurement target by laser ablation and a detection laser to measure these induced vibrations. The validity of the method is verified by comparison with the results of a hammering test. It is shown that remote laser sensing can be successfully applied to a reinforced concrete tunnel lining, although the induced vibrations decay faster and the noise level are higher in the field than in the laboratory. Changes in natural frequency are occasionally observed; these are believed to be a results of changes in temperature and nonlinear vibrations. Based on the results of on-site laser measurements, the estimated frequency of the lowest mode is found to be the most useful index for the quantitative evaluation of defects.

本文考虑了远程激光传感技术在怀疑钢筋腐蚀的情况下在钢筋混凝土隧道衬砌中的适用性。作为锤击测试的替代方法，这种方法代表了一种非接触式检查方法，可以提供定量评估。远程激光传感使用两种类型的激光：冲击激光通过激光烧蚀在测量目标中引起振动，而探测激光则在测量这些引起的振动。通过与锤击测试的结果进行比较，验证了该方法的有效性。结果表明，尽管感应振动衰减更快并且现场的噪声水平高于实验室，但远程激光感测可以成功地应用于钢筋混凝土隧道衬砌。偶尔会观察到自然频率的变化；这些被认为是温度和非线性振动变化的结果。根据现场激光测量的结果，最低模式的估计频率被发现是对缺陷进行定量评估的最有用指标。