超长密集群桩对邻近隧道影响的数值分析

Numerical analysis of the effects of ultra deep and compact group piles on adjacent tunnels

采用FLAC3D程序建立数值模型,针对高层建筑物群桩基础不同工况,对邻近已有隧道的影响问题进行了探讨.分析结果表明:群桩与隧道的净距离对隧道沉降有较大影响,工程中布置群桩基础应尽可能远离隧道;随着桩间距的增加,桩基对于邻近隧道的影响逐渐减小,且垂直于隧道轴线方向的桩间距的变化对于邻近隧道沉降的影响效果更为明显.因此,在实际工程的群桩桩位布置过程中,应尽可能考虑增加群桩重心与隧道之间的净距,以减小桩基沉降对隧道的影响;另外,增加桩长对降低隧道受到的影响较为明显,但减小沉降的效益随着桩长增加而降低,需要选择合理的桩长来控制建筑成本以及对邻近隧道的影响.研究结论为制定保护地铁隧道的相应措施提供理论依据.

FLAC3D program is used to establish a numerical model, the influences of high-rise building pile foundation under different working conditions on adjacent existing tunnels are discussed. The results show that the distance between group piles and tun- nels has great influence on the tunnel settlement, pile group foundation should be layout from the tunnel as far as possible. With the increase of pile spacing, the influence of pile foundation on the adjacent tunnel is gradually decreasing, and the pile spacing changes which is vertical to the axial direction of the tunnel is more obvious for tunnel subsid- ence. Therefore, in the practical engineering, the arrangement of group piles should be considered to increase the distance from the pile gravity center to the tunnel in order to reduce the effect of tunnel caused by the pile group settlement. In addition, increasing the pile length can obvious reduce the effect to the tunnel,but settlement reducing effi- ciency is gradually decreased with the increase of the pile length. In practical engineer- ing, it needs to choose a reasonable pile length. The conclusion can provide a theoretical basis for the development of the corresponding protection measures for subway tunnels.