超深基坑施工支护结构受力变形实测分析

Analysis of the measured data of force and deformation of the support structure for an ultra-deep excavation project

结合上海硬X射线项目一号工作井超深开挖、超长降水周期的工程实践,通过对围护结构变形、支护体系受力等全面的信息化监测,研究探讨了超深基坑施工围护结构的变形规律和支撑体系的受力状态,提出了基坑施工的变形控制建议,以保证基坑围护体系安全运行,同时为软土地区同类超深基坑设计和施工提供借鉴和参考。根据实测分析发现:1200mm厚超深地下连续墙自身刚度较大,抗变形能力较强,开挖阶段地下连续墙变形只发生在应力释放初期;砼支撑对地下连续墙和立柱的隆起约束较大,立柱的隆起量比地下连续墙隆起量大2~2.8倍;与设计轴力相比,斜撑实测轴力增长要小于对撑。

A case study on the ultra-deep and ultra-long dewatering period of the deep excavation of the Shanghai High Repetition Rate XFEL and Extreme Light Facility was carried out. Based on the monitoring data of the retaining structure deformation and stress in the bracing beams,the deformation laws and the stress state of the supporting system is studied. At the same time,a reference for the design and construction of similar ultra-deep excavation works in soft soil areas is proposed. According to the monitoring results,it is found that the 1200 mm thick ultra-deep diaphragm wall is rigid and strong enough to resist the deformation.The deformation of diaphragm wall only occurs in the initial stress release stage during the excavation period;concrete struts will constrains the uplift of diaphragm wall and lattice columns;the uplift of lattice column is 2 ~ 2. 8 times greater than that of the diaphragm wall;compared with the designed axial force,the measured axial force increase of the flying shores is smaller than that of the diagonal strut.