岩-土交界面处超大直径过江盾构隧道地震响应特征

Seismic Response Characteristics of River-crossing Shield Tunnel of Large Diameter at Rock-Soil Interface

以武汉市三阳路超大直径过江“公铁合建”盾构隧道工程为依托,探讨了强震作用下岩-土交界面处隧道的损伤演化规律及地震响应包络特征。基于ABAQUS软件研发的动力有限元计算平台,建立了双隧道(含内部构件公路板与竖向隔板)-土体有限元模型,土体本构采用了修正的Davidenkov黏弹性动力本构模型,混凝土本构采用损伤塑性模型以模拟其开裂、损伤特征。计算结果表明:在岩-土交界面附近,盾构隧道衬砌的加速度、位移及应力响应均出现突变;由于隧道结构穿越了软硬土层,其破坏始于拱腰的退出工作,进而衬砌内部构件节点破坏,拱肩最后破坏;衬砌拱腰处的破坏区域均在岩-土交界面附近的软土层中;衬砌内部构件的存在使得超大直径衬砌拱侧的水平剪应力明显减小。

The damage evolution laws and the envelope characteristics of seismic response of tunnel crossing rock-soil interface under strong earthquake were studied with the large-diameter river-crossing highway-and-subway-combined shield tunnel built in Sanyang road,Wuhan city as research background.A model composing twin tunnels(containing inner components:horizontal highway plate and vertical partition plate)and soil was established using the dynamic finite element numerical platform in ABAQUS.The dynamic viscoelastic model,modified Davidenkov model,was employed to model the characteristics of soil,while the concrete damage plasticity model was adopted to model the fracture and damage of tunnels.Results revealed abrupt changes in the acceleration,displacement,and stress response of shield tunnel lining in the vicinity of rock-soil interface.Due to the existence of rock-soil interface,the haunch of tunnel is destroyed first,and then the joints of inner components and at last the spandrel.The seismic damage of haunch mainly occurred in the soft soil part.The inner components reduced the horizontal shear stress at both sides of the large-diameter tunnel.