短时脉冲激励下隧道振动响应与模态参数识别

为了研究短时脉冲激振力下隧道结构振动响应及有效地提取隧道结构的模态特征。首先分析了锤击作用下的不同短时脉冲激振力精度及其频域特性,其次将短时脉冲激振力应用于上海地铁12号某盾构隧道进行了现场动力测试,最后分析了脉冲激振与隧道结构响应之间的传递函数,并结合随机减量、正交多项式法及自回归滑动平均模型法有效地提取隧道结构的模态参数。结果表明:短时脉冲激振力的中低频振动信号在隧道结构中传递特性较好,传递距离较远。隧道结构的模态频率呈现明显低频特征,前10阶模态频率在100 Hz以下。因此,短时脉冲激振力能够很好地应用于隧道动力测试及模态识别,可为基于模态特征的隧道结构损伤识别及健康监测多个研究领域提供有效的支撑和参考依据。

Dynamic Response Analysis and Modal Parameters Identification of Tunnel Structure Under the Short-Time Impulse Force Excitation

This paper studied the dynamic response of a tunnel structure under short-time impulse force excitation and identified the modal parameters. First, the precision and frequency domain feature of the short-time impulse force excitation under the actions of different hammering were analyzed. Second, the short-time impulse force excitation was applied in an in-site vibration test in a shield tunnel of Shanghai metro line 12. Finally, the frequency response functions between the impulse force excitation and the vibration response at measured points of the tunnel were carried out and combined with random decrement, orthogonal polynomial, and ARMA methods, in order to effectively identify the modal parameters of the tunnel structure. The results showed that the low and medium frequency transmission of the vibration signal was quite good, and the transmission distance was long. The modal frequency of the tunnel structure was obviously presents low frequency characteristics, and the first ten model frequencies were under 100 Hz. As a result, the short-time impulse force excitation can be applied to a tunnel vibration test and the identification of its modal parameters. It can provide effective support and a reference base for tunnel structure identification and structural health monitoring based on the modal characteristics.