关键词: 盾构隧道, 预制中隔墙, 底部节点, 拟静力足尺试验, 刚度, 承载力

Abstract: The skeleton curve of the bottom joint of prefabricated partition walls in large-diameter shield tunnels is crucial for evaluating the designed load-bearing state of the partition walls during operation. Herein, a case study is conducted at the Baiyun Central station-Fangshi station section of the Guangzhou East railway station-Huadu Tiangui intercity railway, and a quasi-static full-scale experiment is implemented to investigate the mechanical properties of the bottom joints of prefabricated partition walls. Low-cycle loading tests are carried out on cast-in-place and prefabricated partition walls, yielding the mechanical properties of their bottom joints. The main findings are as follows: (1) Partition walls exhibit bending-induced cracking before yielding, with cracks gradually developing from the wall foot to the top. Owing to high stiffness, the cast-in-place wall ultimately undergoes shear failure. In contrast, the prefabricated wall without circumferential stirrups exhibit intersecting diagonal cracks at the wall base, eventually leading to bond failure. (2) The connection between the partition wall and the under-track structure in the cast-in-place specimen is reliable and exhibits no cracking at specimen failure. However, the prefabricated partition wall shows detachment at the connection before yielding, although the connection still maintains adequate load-bearing capacity at specimen failure. (3) The bottom joints of both cast-in-place and prefabricated partition walls do not crack under the current design load. However, it is recommended to install circumferential stirrups at the bottom of the partition wall to enhance load-bearing capacity and prevent the occurrence of X-shaped diagonal cracks. (4) The cast-in-place specimen demonstrates higher stiffness and load-bearing capacity but lower deformation capacity and energy dissipation, whereas the prefabricated specimen, although slightly inferior in stiffness and load-bearing capacity, exhibits superior ductility and energy dissipation performance.

Key words: shield tunnel, prefabricated partition walls, bottom joint, quasi-static full-scale experiment, stiffness, load-bearing capacity