地连墙补强桩对填海区深基坑的稳定性影响分析

Impact analysis of of diaphragm wall reinforcing piles on stability of deep foundation pits in reclamation areas

填海区地层含深厚人工填土层及软土地层,部分既有地下连续墙嵌入深度不满足前海站深基坑稳定开挖要求。为利用既有地下连续墙,在地连墙嵌入深度不足部位设置钻孔灌注桩进行补强加固。本文利用有限元软件Flac^(3D)进行数值模拟,研究补强桩的受力和变形特性以及补强桩上部凿除对前海站深基坑稳定性的影响规律。研究表明:1)补强桩加固段地连墙的最大水平位移满足规范要求,但墙底水平位移较大,而补强桩的设置有效防止了坑底地连墙失稳;2)补强桩的变形为反S型,桩身最大弯矩为1010.20 kN·m,小于桩的受弯承载力;3)补强桩部分凿除后,对地连墙的水平位移影响较小,但地表沉降量增加。

The stratum of the reclamation area contains deep artificial fill stratum and soft soil stratum,and the embedded depth of some existing diaphragm wall does not meet the requirements for stable excavation of deep foundation pits in Qianhai Station.In order to make use of the existing diaphragm wall,bored piles are set up at the part with insufficient embedded depth of the diaphragm wall for reinforcement.The finite element software Flac3 D is used for numerical simulation to study the stress and deformation characteristics of the reinforcing piles and the influence of the upper part of the reinforcing piles on the stability of the deep foundation pits of Qianhai Station.The results show that:1)The maximum horizontal displacement of the diaphragm wall in the reinforced section of the reinforcing piles meets the requirements of the code,but the horizontal displacement at the bottom of the wall is large,and the setting of the reinforcing pile effectively prevents the diaphragm wall at the bottom of the pit from losing stability;2)The deformation of the reinforcing pile is reverse S-shaped,and the maximum bending moment of the pile body is 1010.20 kN·m,which is less than the bending bearing capacity of the pile;3)After the reinforcing piles are partially chiseled,the horizontal displacement of the diaphragm wall is less affected,but the ground settlement is increased.