基坑不同施作顺序引起邻近车站变形对比分析

Comparison Analysis of Construction Sequence of Deep Foundation on the Deformation of Nearby Existing Subway Station

研究目的:邻近已建成地铁车站深基坑开挖卸载会引起车站结构不均匀变形,而不同施作顺序对其变形特性的影响还缺乏系统认识。结合长沙地区某地铁车站工程实例,基于数值方法对不同施作顺序下深基坑开挖引起的邻近地铁车站变形规律进行对比分析,并探讨车站基坑明挖顺作段和盖挖逆作段在不同开挖深度时围护结构及车站主体结构的变形特性。研究结论:(1)随着开挖深度的增加,地铁车站围护结构水平变形逐渐增大;(2)明挖顺作段由于基坑开挖引起的邻近地铁车站变形要明显大于盖挖逆作段;(3)盖挖逆作段由于基坑开挖引起的地面沉降变形较小,而不同施作顺序下地表沉降值均在结构安全和正常使用要求的范围之内;(4)该研究成果可为邻近既有地铁车站深基坑设计与施工提供参考。

Research purposes： The excavation of deep foundation will induce differential deformation to the nearby existing subway station, whereas the deformation due to different construction sequence has not been generally investigated. The comparison analysis of construction sequence on the regular pattern of deformation for the nearby existing subway station was conducted, which was based on one field case located in Changsha and numerical analysis. The deformation characteristic of retaining structure and main structure of nearby existing subway station was also analyzed for the zone excavated using bottom - up method and top - down inverse construction method at different excavation depth. Research conclusions： （1） The lateral deformation of retaining structure increased gradually with increasing the excavation depth. （2） The deformation of nearby existing subway station at the zone excavated using bottom - up method was obviously larger than that at the zone using top - down inverse construction method. （ 3 ） The surface settlement induced by excavation was smaller using top - down inverse construction method, whereas the surface settlements for different construction sequence were in the range of safety and normally use requirements. （4） The research results can provide references for the design and construction of deep foundation nearby existing subway station.