有变形缝工况下地铁左右线盾构并行下穿对既有明挖公路隧道变形及应力的影响

Influence of Metro Shield Left/Right Line Tunnel Parallel Under-passing on the Defor-mation and Stress of Existing Open-cut Highway Tunnel under Deformation Joint Working Condition

[目的]为确保有变形缝工况下地铁盾构隧道并行下穿既有明挖公路隧道工程的顺利实施,须对该工况下既有明挖公路隧道的变形情况及应力特征进行分析。[方法]建立了济南济泺路下穿黄河隧道工程中市域轨道交通S2线左右线盾构隧道并行下穿既有明挖公路隧道的精细化模型,分析了既有明挖公路隧道车道结构底板的z向(竖向)沉降、x向(水平向)位移及车道结构底板的应力变化情况。选取有无变形缝2种工况,对2个施工步完成后测线的x向位移和z向沉降变化情况进行对比。进一步选取工程中的2号变形缝,分析施工过程中2号变形缝两侧的结构沉降差和变形缝的应力状态发展历程。[结果及结论]与无变形缝工况相比,有变形缝工况降低了既有明挖公路隧道结构的整体性,改变了其变形及受力特征;变形缝始终受到拉应力及剪应力的影响;有变形缝工况下,变形缝两侧沉降随地铁盾构掘进呈现出明显的变化,地铁盾构掘进至该变形缝正下方时,沉降达到最大值。

[Objective]To ensure the successful implementation of metro shield tunnel parallel under-passing through the existing open-cut highway tunnel project under deformation joint condition,it is necessary to analyze the deformation situation and stress characteristics of the mentioned highway tunnel under this working condition.[Method]A refined model of Jinan Rail Transit Line S2 left/right shield tunnel parallel under-passing of the existing open-cut highway tunnel in Jiluo Road Yellow River Tunnel project is established.The z-direction(vertical)settlement,x-direction(horizontal)displacement,and stress change of this highway tunnel structure bottom plate are analyzed.Through establishing two working conditions with and without deformation joint,changes of the z-direction settlement and x-direction displacement of the mea-sured line are compared.By selecting No.2 deformation joint in the project,the settlement difference and stress state development history on both sides of No.2 deformation joint are further analyzed.[Result&Conclusion]Compared to the working condition without deformation joint,that with deformation joint reduces the structural integrity of existing open-cut highway tunnels and changes its deformation and force characteristics.Deformation joints are always subject to tensile and shear stresses.Under deformation joint working condition,settlement on both sides of the deformation joint shows significant changes with the tunneling of metro shield,and reaches its maximum value when the tunneling is directly beneath the deformation joint.