地铁车站隧道群施工对邻近桥桩影响的数值分析

地铁隧道施工对邻近隧道和其他既有结构的影响问题是城市轨道交通建设中的常见问题.广州市某地铁车站由多个水平和倾斜的隧道组成,与既有城市道路桥梁桩基距离很近.研究选择合理有效的三维非线性数值模拟方法,分析隧道群施工对邻近道路桥梁桩基的影响方式和影响水平,从而为设计与施工提供依据.计算分析表明:①可通过较简单的模型来模拟较复杂的隧道洞群-桥基关系;②隧道所穿越地层的变形和强度特征可能会比隧道埋深对地表下沉和桥桩变位造成更显著的影响,在此情况下,对隧道边墙及附近地层的支护和加固与对隧道拱部的支护和加固同样重要;③相对于隧道埋深较短的桥桩,补强桩必须具有足够的深度才能有效地控制原有桥桩的下沉.

Numerical Analysis of the Multiple Tunneling Effects at A Metro Station Construction on Adjacent Bridge Piles

It constitutes a common problem that urban tunneling exerts negative influences on nearby tunnels and existing structures. A metro station in the city of Guangzhou is composed of several horizontal and inclined tunnels, which are very close to some of the pile foundations of a road bridge. With this metro station project as the background, this paper addresses the approach for formulating 3-D nonlinear numerical models to efficiently simulate the effect of the multiple tunneling on the adjacent bridge piles. The analyses indicate that it is feasible to employ simplified models to simulate the rather complex multiple tunneling and pile relationships. The results also suggest that the rigidity and strength of the ground, into which the tunnel is constructed, may impacts the ground surface settlements and pile deformations more ostensibly than the depth of the tunnel, and to those short piles with respect to the tunnel elevation, the reinforcement piles have sufficient depths so that the settlements of the existing piles could be effectively controlled.