间接测量法在盾构隧道模态识别中的应用研究

Application of indirect measurement method in modal identification of shield tunnel

为了快速、经济且准确地实现盾构隧道的健康监测,将桥梁健康监测的间接测量法应用于盾构隧道结构中,在推导了移动车辆-盾构隧道耦合振动作用下车辆加速度响应解析解的基础上,分析了考虑阻尼影响的盾构隧道振型间接识别方法,从理论上证明了间接测量法在盾构隧道模态识别中应用的可行性。通过实验室试验验证盾构隧道频率间接识别方法,试验结果表明,采用间接测量法与直接测量法测试得到的盾构隧道频率接近,误差为2.8%。同时,通过数值算例验证了基于间接测量法的盾构隧道频率、振型、阻尼比识别方法,并分析车辆速度、车辆阻尼、盾构隧道阻尼等参数对盾构隧道模态间接识别结果的影响。分析结果发现:车速对频率间接识别的影响较小,而过低的车速会导致振型无法识别,应选择5 m/s以上的车速;车辆阻尼大小对振型间接识别的影响较小,而增大车辆阻尼有利于频率间接识别;盾构隧道阻尼的增大不利于频率和振型的间接识别。

In order to realize quick, economical and accurate health monitoring of shield tunnel, an indirect measurement method is applied to bridge health monitoring for shield tunnel structures. Based on the derived analytical solution of vehicle acceleration response under coupled vibration of moving vehicle-shield tunnel, the indirect identification method for obtaining the shield tunnel mode shape considering the influence of damping is analyzed, which theoretically proves the feasibility of the application of the indirect measurement method in shield tunnel modal identification. The indirect identification method for obtaining the shield tunnel frequency is verified by laboratory tests, and the test results show that the shield tunnel frequencies obtained by the indirect measurement method are very close to those obtained by the direct measurement method, with an error of 2.8%. Meanwhile, the method for identifying shield tunnel frequency, vibration mode and damping ratio based on the indirect measurement method is verified by numerical examples. The influences of parameters such as vehicle speed, vehicle damping, shield tunnel damping on shield tunnel modal indirect identification results are analyzed. The results show that vehicle speed has little influence on the indirect frequency identification, but an excessive low speed will lead to failure in recognizing the vibration mode, so a speed exceeding should be selected. Vehicle damping has little influence on the indirect mode identification, while increasing the vehicle damping is beneficial to the indirect frequency identification. Increasing shield tunnel damping is detrimental to indirect identification of frequency and mode.