关键词: 软土地层, 城市核心区, 主动控制型, 装配式沉井, ACPP工法

Abstract: Due to low control accuracy of sinking speed, depth, and verticality, conventional sinking method poses adverse impact on surrounding environment when applying in coastal soft soil regions. To address this issue, a case study is conducted on an escape shaft project on the Xingle road in the west extension of the Shanghai metro line 13, and mechanized, automated, and intelligentized innovations are conducted based on conventional sinking method, proposing an active control press-in prefabricated shaft construction method. This method employs load and sinking thrust bivector stable sinking mechanism without dewatering operation. The prefabricated shaft walls are pressed in under propulsion and suspension system through hoist-pressin modes, the soil is automatically excavated by underwater excavation system with active control six degree of freedom, and the thixotropic-static antifriction slurry is synchronously grouted. A machine-soil-structure cooperative, virtual, digital, remote control technology integrating excavation conditions, sinking parameters, shaft posture, and environmental monitoring is achieved, realizing accurate and stable sinking of shaft structures in coastal soft soil regions. The results show that: (1) After the completion of the shaft sinking, the height difference at the bottom of the shaft is less than 1 mm, the vertical deviation is less than 1‰, the average maximum horizontal displacement of soil is 5.10 mm, and the maximum surface settlement is 4.81 mm. (2) The formed shaft is complete and straight without leakage, demonstrating superior construction effect than similar projects.

Key words: soft soil strata, urban core area, active control, prefabricated shaft, active control pressin prefabricated construction method