超长车站深基坑开挖施工顺序影响规律

Influence of Construction Sequence on Deep Foundation Pit Excavation of Super-Long Station

超长车站基坑开挖过程中,不同开挖顺序下支护结构的受力状态、变形特性会出现明显差异。基于穗莞深城际铁路前海站基坑工程,采用数值模拟对比分析4种不同开挖方案下围护结构变形、地表沉降及内支撑轴力变化规律,并对数值模拟结果进行验证,选出最有利于支护结构稳定的施工方案。结果表明:超长车站基坑在开挖过程中会表现出明显空间效应,基坑边角对结构变形有显著约束作用;围护结构变形与地表沉降呈正相关关系;先开挖基坑两端区域,围护结构位移与地表沉降最小;同步开挖工序下,内支撑轴力最小。通过对比分析,为超长深基坑开挖施工提供了合理方案。

During the excavation of the foundation pit of the super-long station,the stress state and deformation characteristics of the supporting structure under different excavation sequences will be significantly different.Based on the foundation pit project of Qianhai Station of the Guangzhou-Dongguan-Shenzhen Intercity Railway,numerical simulation is used to compare and analyze the deformation of the enclosure structure,the surface settlement and the change of the axial force of the inner support under four different excavation schemes,and the numerical simulation results are verified.The construction plan that is most conducive to the stability of the supporting structure is obtained.The results show that:the super-long station foundation pit will show obvious spatial effects during the excavation process,and the corners of the foundation pit have a significant constraining effect on the structural deformation;the deformation of the enclosure structure is positively correlated with the surface settlement;the two ends of the foundation pit are excavated first.In the area,the displacement of the enclosure structure and the surface settlement are the smallest;under the simultaneous excavation process,the axial force of the inner support is the smallest.Through comparative analysis,a reasonable scheme is provided for the excavation of super-long and deep foundation pits.