跨越地铁隧道超高层建筑桩筏基础数值模拟及优化设计

Numerical simulation and optimized design of piled raft foundation of super-tall building crossing metro tunnel

基于某跨越地铁超高层建筑的设计实践,采用Mohr-Coulomb屈服准则,利用ABAQUS建立三维有限元数值模型,研究地铁隧道穿越建筑物基础时对桩筏基础变形和内力的影响,并根据数值计算结果对经验方法的设计进行优化。数值分析结果表明:开挖增大了筏板的弯矩;隧道开挖会引起附近群桩向隧道方向挠曲变形,且前排桩的变形大于后排桩的变形,同一排桩中边桩变形大于中桩变形;隧道开挖对桩的桩身轴力、弯矩及水平变形的影响主要发生于桩顶至3倍隧道埋深的桩身范围内;随着盾构掘进正面推力和径向压力的增大,桩身挠曲变形逐渐减小并最终使桩身发生远离隧道方向的挠曲变形。

Based on the design practice of a super-tall building crossing metro tunnel,a three-dimensional,elasto-plastic numerical simulation was conducted by using software ABAQUS to investigate the deformation and internal forces of piled raft foundation due to the passage of a metro tunnel.The mohr-coulmb yield criterion was adopted for soil.According to the numerical results,the experiential design was optimized.The numerical results indicate that bending moment of the raft increases due to tunnel excavation.Adjacent piles are bending towards tunnel,and the horizontal deformation of piles in front row is lager than those of rear row.In the same row,deformation of the side pile is larger than that of the middle pile.Furthermore,the variation of internal force and horizontal deformation of piles mainly occur in the zone of three times of embedded depth of tunnel along piles.With the increment of the force of shield construction,the horizontal deformation of piles decreases.