盾构隧道-土体接触耦合机制的模态特征分析

盾构隧道动力特征受隧道衬砌结构及壁后土体相互耦合作用影响，为了分析隧道-土体接触耦合机制，以上海地铁某区间盾构隧道为研究背景，采用Bucket搜索法通过分析节点接触和弹性地基接触两种不同类型接触耦合下隧道结构的模态特征，并将分析结果与地铁隧道现场动力实测提取的模态特征进行比较。结果表明：隧道结构受土体耦合约束作用，呈现低频特性，前10阶模态频率在0～100 Hz范围内，模态振型幅值在10?4 m的数量级上。弹性地基接触与实测提取模态特征误差较小，可用于隧道结构动力分析模型简化和理论研究，为隧道结构动力损伤识别提供依据。

Modal characteristics analysis of contact coupling mechanism between shield tunnel and soil

The dynamic behaviors of shield tunnel are influenced by the coupling interaction between the tunnel lining structure and soil behind lining wall. In order to analyze the tunnel-soil contact coupling mechanism, a shield tunnel in Shanghai metro is selected as study case; the Bucket method is used to analyze the modal characteristics of the tunnel structure under the two different types of contact couplings including node contact coupling and foundation contact coupling. The analysis results are compared to the tunnel modal characteristics extracting from the in-site vibration test data. The results show that constrained by soil coupling, the tunnel structure presents a low frequency characteristic, the first tenth order modal frequencies range are between 0 and 100 Hz, and the modal shape amplitudes are on the order of 10?4 m. And the most important is that there is a small error between the elastic foundation contact and the measured modal characteristics, which can be applied to simplifying the model of dynamic analysis of tunnel structure, and also provide a basis for tunnel structure damage identification based on the modal characteristics.