The stiffness mutation of shield tunnel-shaft junction makes the tunnel structure affected by the differential displacement and forms a complex spatial effect. Taking the subsea shield tunnel crossing under the Shantou Gulf, China, as a case study, a three-dimensional finite element global model and a refined local spatial end submodel are established. The nonlinear dynamic behaviors of the seabed soil and concrete, the simulation of the bolt joints between ring segments by using cohesive models and the SMA shape memory alloy flexible joints, and the input ground motions produced by scaling from the high-level earthquake records are considered in detail. The results show that the shield tunnel spatial end structure increases nonlinearly in response to the increase of seismic motion intensity. The opening width and the deformation between ring segments at the vault and the outside spandrel are larger, and serious seismic damage and stress concentration exist at the conjugate 45° directions of shaft. The seismic responses of the tunnel-shaft junction subjected to the seismic motions with rich low-frequency components are much stronger than those of seismic motions with rich high-frequency components. Adding SMA flexible joints, the structural deformation caused by seismic motion propagation can be induced to the preset flexible joint, and the structural damage and stress concentration can be effectively reduced. The seismic response characteristics of shield tunnel spatial end structure calculated by the global model are consistent with those calculated by the submodel, while the seismic response of the submodel is greater than that of the global model.

中文翻译：

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盾构隧道空间端部结构三维非线性地震响应

盾构隧道-竖井连接处的刚度突变使隧道结构受到位移差的影响，形成复杂的空间效应。以汕头湾海底盾构隧道穿越为例，建立三维有限元全局模型和精细局部空间端子模型。考虑了海底土壤和混凝土的非线性动力行为，使用内聚模型和 SMA 形状记忆合金柔性接头模拟环段之间的螺栓接头，以及从高级地震记录缩放产生的输入地面运动详细。结果表明，盾构隧道空间端部结构随着地震活动强度的增加呈非线性增加。拱顶处环段与外拱肩的开口宽度和变形较大，在竖井共轭45°方向存在严重的地震破坏和应力集中。隧道-竖井交界处在低频分量丰富的地震运动下的地震响应远强于高频分量丰富的地震运动。加入SMA柔性接头，可以将地震运动传播引起的结构变形诱导到预设的柔性接头上，有效减少结构损伤和应力集中。全局模型计算的盾构隧道空间端部结构地震响应特征与子模型计算的一致，