地震作用下盾构隧道纵向接头的受力特征

Force Characteristics of Longitudinal Joints of Shield Tunnel under Seismic Action

实际工程中,盾构隧道纵向接头是结构受力和变形的薄弱部位,针对盾构隧道纵向接头细部构造在地震作用下的受力特征,提出了一套由整体到局部的数值分析流程.首先建立基于纵向等效刚度梁的三维地层-结构时程分析模型,然后以该模型计算得到的纵向内力极值作为盾构隧道整环三维分析模型的外荷载,获取隧道最不利区域边界力,最后将边界力施加在盾构隧道纵向接头局部精细化分析模型之上,分析纵向接头细部构造受力特征;并以某综合管廊工程为背景对该方法进行具体阐述和讨论.研究结果表明:地震波横向激励时,盾构隧道纵向以往复的水平弯曲为主,而纵向激励时,则以往复的竖向弯曲和纵向拉压为主;在纵向张开量最大的局部区域,不论是轴向拉力工况还是纵向水平弯矩工况,该局部区域都处于受拉状态,两种工况对该局部区域受力模式不产生本质影响;当盾构隧道纵向最大张开量的局部区域受拉时,最大拉应力区均位于管片内侧手孔部位,最大压应力区则围绕螺栓孔成环形分布.

The longitudinal joints of shield tunnels are the weak parts of the structure when bearing loads and deformations in practical engineering.A numerical analysis method which analyzes from the whole to the local was put forward based on the mechanical characteristics of the longitudinal joints under seismic action.According to the equivalent longitudinal stiffness beam theory,the 3D time-history analysis model of stratumstructure was established to obtain the extreme value of structural longitudinal internal force,the extreme value was then taken as the external load which was applied on the entire 3D analysis model of the whole ring to obtain the boundary force of the most unfavorable region of shield tunnels.The mechanical characteristics of the longitudinal joints were analyzed by applying the boundary force to the local refined model of the longitudinal joints.The method was discussed by an integrated corridor project specifically.The results show that the shield tunnels mainly suffer cyclic horizontal bending in the longitudinal direction when it is under the transverse seismic excitation,the cyclic vertical bending and longitudinal tension of the tunnel are notable when the seismic wave is excited longitudinally.The local area with the largest longitudinal opening is always under tension whether subjected to axial tension or longitudinal horizontal bending moment,which means that the influence of these two working conditions on the force pattern of the local area are essentially the same.When the local area with the largest longitudinal opening is under tension,the maximum tensile stress area is located at the hand hole on the inside of the segment,and the maximum compressive stress area is distributed around the bolt hole in a ring shape.