西安地铁6号线某隧道穿越地裂缝带设防措施研究

Protective Measures for a Tunnel on Xi’an Metro Line 6 Crossing Ground Fissure Zone

[目的]西安地铁6号线二期工程某隧道沿线分布有7条地裂缝,工程性质较差,施工时可能会造成隧道局部坍塌,以及基底不均匀沉降,从而加剧地裂缝活动,严重威胁城市轨道交通的建设和运营。因此,有必要对6号线某隧道穿越地裂缝带进行设防研究。[方法]基于对与西安地铁6号线二期工程相交的各条地裂缝历史活动特性分析,对各条地裂缝对地铁影响程度分级进行定性评价。综合该分级定性评价结果,隧道与地裂缝的空间相对关系,以及地裂缝在百年使用期内最大垂直位移量设计建议值,对地裂缝垂直、水平及轴向位移量,以及隧道结构纵向设防长度进行了估算。依据二类地裂缝场地的工程防治原则,针对隧道穿越地裂缝带提出相应设防措施。[结果及结论]6号线某隧道穿越地裂缝带的设防措施为:隧道衬砌结构采取分段设缝,扩大隧道断面净空及局部衬砌加强,接缝处采用柔性接头。该设防措施目前已经成功保障了7条地铁线路的安全施工与运营。

[Objective]Xi’an Metro Line 6 PhaseⅡproject encounters seven ground fissures along one of its tunnels,the poor engineering properties may cause partial tunnel collapse and uneven settlement at the base,exacerbating ground fissure activities and posing serious threats to the construction and operation of urban rail transit.Therefore,it is essential to study protective measures for this Line 6 tunnel crossing ground fissure zones.[Method]Based on the historical activity characteristics of the ground fissures intersecting Xi’an Metro Line 6 PhaseⅡproject,a qualitative evaluation of the impact levels of each fissure on metro is conducted.Combining this qualitative evaluation results with the spatial relationship between the tunnel and the fissures,as well as the design value of recommended maximum vertical displacement for the fissures during a 100-year service life,estimates are made for the vertical,horizontal and axial displacements of the fissures and the longitudinal protective length of tunnel structure.According to the engineering prevention principles for ClassⅡground fissure sites,corresponding protective measures are proposed for the tunnel crossing fissure zones.[Result&Conclusion]The protective measures for a Xi’an Metro Line 6 tunnel crossing ground fissure zones include:adopting segmental seams for tunnel lining structure,increasing tunnel cross-sectional clearance,reinforcing local linings,and using flexible joints at the seams.These protective measures successfully ensure the safe construction and operation of seven metro lines.