Analysis on the monitoring results of construction deformation and internal force of ultra-deep circular foundation pit of Dianzhong Water Diversion Project
Xu Qianwei1 Gong Zhenyu2 Sun Zili1 Hu Rucheng2 Hu Kaifu3
1. Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety, Tongji University, Shanghai 201804, China;
2. The Electricity Engineering Co., Ltd., under CREC No.5 Group, Changsha 410205, China;
3. Central Yunnan Provincial Water Diversion Project Construction Administration Branch, Kunming 655600, China
Abstract：By taking the 77.3 m deep circular foundation pit project of the Longquan Inverted Siphon Shield Receiving Well in Central Yunnan as an example, the force and deformation laws of the circular foundation pit are studied based on the monitoring data. The research results show that: (1)The excavation of the foundation pit may cause the cylindrical diaphragm wall to gradually become an elliptical tube shape which elongates in one direction but shortens in the other direction, and the deformation values towards the inside and outside of the foundation pit are small and far lower than the requirements in current codes for the deformation of the foundation pit of grade I. (2)During the excavation of ultra-deep circular foundation pit, the circumferential steel bars on the outer side of the diaphragm wall are mainly under compression, the inner circumferential steel bars may be subject to local tensile stress, while the vertical steel bars shall be partially tensioned and partially compressed caused by the spatial deformation of the tubular structure. (3)The bending moment on the wall is relatively small, and the maximum bending moment is only -390 kN·m occurring at the excavation depth of 40 m. (4)The ground surface deformation mainly appears to be upheaval, without effective slippage occurring between the diaphragm wall and the soil. The excavation and unloading effect of the stratum tends to uplift the diaphragm wall and its surrounding soil. (5)The drawdown of groundwater level around the foundation pit is very small, indicating that the use of milling joints for the diaphragm wall in this project may ensure the integrity of the circular structure very well and good water-proof performance.
徐前卫 龚振宇 孙梓栗 胡如成 胡开富. 滇中引水工程超深圆形基坑施工变形和内力监测结果分析[J]. 土木工程学报, 2022, 55(6): 102-111.
Xu Qianwei Gong Zhenyu Sun Zili Hu Rucheng Hu Kaifu. Analysis on the monitoring results of construction deformation and internal force of ultra-deep circular foundation pit of Dianzhong Water Diversion Project. 土木工程学报, 2022, 55(6): 102-111.
