某工程为运营地铁上盖旧楼改造扩建超限高层建筑,需解决新楼建设、旧楼加固改造不影响地铁安全,新楼与旧楼结构连接等复杂难题。基坑设计中采用满堂三轴搅拌桩封底并分区施工、采用冷冻法截水、地连墙既是基坑围护结构又是主体结构基础“二墙合一”以保证地铁及旧楼安全;基础设计中采用钢套筒减摩桩以消除基桩上部摩擦力对地铁隧道的影响;结构设计中主楼与旧楼连接采用铰接与刚接包络设计保证连接可靠性,旧楼顶新加楼层通过转换桁架直接传力到基础,保证旧楼基础及结构不增加荷重。对工程进行了结构抗震性能化超限设计,小震、中震、大震分析结果表明结构设计满足要求,对类似工程极具参考意义。 A project to operate the MTR superstructure renovation and expansion of overbuilding high-rise buildings, the need to address the new building construction, renovation of the old building does not affect the safety of the subway, the new building and old buildings connected to the complex problems. In the design of foundation pit, full-floor triaxial mixing piles are used to seal the bottom and partition construction. The freezing method is used to cut off water. The wall is not only the foundation pit retaining structure but also the main structural foundation “two walls together ” to ensure the safety of the subway and the old buildings In the basic design, the steel sleeve anti-friction piles are used to eliminate the influence of the upper friction of the pile on the subway tunnel. In the structural design, the connection between the main building and the old building adopts the hinge and the rigid connection envelope design to ensure the connection reliability. The floor is directly transferred to the foundation through the conversion truss to ensure that the load and load on the foundation and structure of the old building are not increased. The seismic performance of the project has been designed to exceed the limit design. The results of small earthquakes, moderate earthquakes and large earthquakes show that the structural design meets the requirements and is of great reference to similar projects.