地震下大断面盾构隧道接缝力学及防水性能研究

Mechanical and waterproof performances of joints of shield tunnels with large cross-section under earthquakes

为研究大断面盾构隧道在地震条件下接缝力学及防水性能,利用ABAQUS分别建立了地层-结构三维有限元模型及密封垫二维有限元实体模型,研究了在不同地震强度下管片接缝的力学性能及错台量与张开量,基于不同位置接缝变形结果讨论了隧道防水性能退化情况。结果表明:(1)中震与大震下左侧拱腰下侧接缝处的最大主拉应力已超过混凝土最大抗拉强度,混凝土出现一定损伤;(2)不同地震强度下纵缝错台量分布规律及大小基本相同,呈"眼镜"状分布,拱顶与拱底错台量相对较小,拱腰与拱脚处错台量较大;(3)拱顶右侧接缝防水能力保持最好,可达2.77MPa,相比正常情况仅削弱16%,环内拱腰附近接缝防水能力削弱严重,防水性能削弱达到40%。

In order to study the mechanical and waterproof performances of joints of large-section shield tunnels under seismic conditions, ABAQUS is used to establish a 3 D stratum-structure finite element model and a 2 D sealing gasket finite element solid model. The mechanical properties, offset, and openings are studied for the segmental joints. Based on the deformation results of the joints at different positions, the deterioration of the waterproof performance of the tunnel is discussed. The results show that:(1) The maximum principal tensile stress of the joints at the lower part of the arch waist under moderate and large earthquakes exceeds the maximum tensile strength of concrete, leading to damage on the concrete.(2) The size of longitudinal joints keeps basically the same under different earthquakes, and their distribution is like a "glass" shape. The amount of misalignment between the arch top and the arch bottom is relatively small, while the amount of misalignment at the arch waist and arch feet is relatively large.(3) The joints at the right side of the dome have the best waterproof capacity of 2.77 MPa, which is only 16% weaker than that under the normal situation. The waterproof performance is severely weakened by 40% at the joints near the arch waist.