考虑管片接头影响的大直径盾构隧道地震响应分析

Seismic Response Analysis of Large-Diameter Shield Tunnels Considering the Segment Joint Effect

管片接缝对盾构隧道的变形及地震响应产生极大影响。文章以南京纬三路大直径过江盾构隧道为研究对象,使用FLAC3D软件建立了真实的管片连接模型,并考虑了三种分块方案,计算了各方案中设计正、负弯矩及轴力所对应的接头转角。通过建立简化的连续非均质圆环模型,依据接头转角等效修正管片接头薄弱区材料刚度,分析了不同分块形式下隧道结构在EI centro波作用下的地震响应。结果表明:分块形式对地震开始后1.2 s内结构的动力特性有影响;封顶块角度越小,拱顶及拱底水平向加速度时程曲线幅值越小;地震结束后三种方案拱顶以及拱底两侧各60°范围内产生较大的拉应力;接头区分布影响断面最大主应力分布,封顶块大小影响最大主应力大小。

Considering that segment joints have a great influence on the deformation and seismic response of shield tunnels, a real segment connection model with FLAC 3D software was established and the rotation angles of the joints as a function of the designed positive and negative moments were calculated along with axial forces considering three segment layout patterns using the Nanjing Weisan Road large-diameter river-crossing shield tunnel as an example. Based on a simplified continuous and heterogeneous ring model, the material stiffnesses at the weak parts of the segment joints were equivalently modified according to the rotation angles, and the seismic responses of the tunnel structures affected by the EI Centro wave were analyzed with respect to different segment layout patterns. The results show that： 1） the segment layout pattern may affect the tunnel dynamic characteristics within 1.2 s after an earthquake; 2） the time-history curve magnitudes of the horizontal acceleration at the crown and bottom decrease with a decrease of the angle of the key segment; 3） regarding the three segment layout pat- terns, the greatest tensile stress may occur in a range of 60° on each side of the crown and bottom after a seism; and 4） the distribution and magnitude of the maximum principle stress are affected by the joint area distribution pattern and the key segment dimension, respectively.