异型断面深基坑开挖与支护数值模拟分析

为了掌握异型断面深基坑施工过程中围护结构受力和变形特征,确保施工安全,以北京地铁6号线3标1号换乘厅工程为例,采取假定简化模型,利用有限元软件ANSYS进行数值模拟计算,并对各个施工工序的计算结果进行对比分析。结论与建议如下:1)类似工程设计时应适当增加桩体长度及与B型桩的连接刚度以增加围护结构的稳定性;2)楼板形成的框架体系约束作用明显,为控制围护结构变形提供了有利条件;3)异型基坑的内支撑体系布置应充分考虑基坑异型带来的薄弱点,在结构断面的变化点应重点关注。通过快速及时完成桩体之间的连接、增大平台下部钢支承的刚度和预应力等措施确保平台稳定。

Analysis on Numerical Simulation of Excavation and Support of Deep Foundation Pit with Irregular Cross-section

In order to acquire the stress and deformation performance of retaining structures and to ensure the construc tion safety of deep foundation pit with irregular crosssection, numerical simulation calculation is made by means of finite element software ANSYS and the calculation results of each construction step are analyzed, with No. 1 transfer hall of No. 3 bid section on No. 6 line of Beijing Metro as an example. Conclusions drawn are as follows ： 1 ） The pile length and the rigidity of the connection to Type B piles should be increased, so as to increase the stability of the retaining structure. 2） The frame structure formed by the floors has obvious constraining effects, which is helpful to the control of the deformation of the retaining structure. 3 ） The weak points of the irregular foundation pits should be considered in the arranging of the internal supporting system of the foundation pit. The ly installing the connection between neighboring piles and increasing the platform. stability of the platform can be guaranteed by rapid the rigidity and prestress of the steel support below