The shield
cannot be received results from delayed construction of metro station main
structure. Therefore, a case study is conducted on the Dashadong station of
Guangzhou metro line 7, and the shield receiving technology in superdeep
foundation pit without main structure is proposed. First, the foundation pit is
excavated to the design elevation and the construction of the main structure of
the end well is suspended. Second, measures such as adjusting the support
position of receiving well, installing sealing device of underground diaphragm
wall tunnel door, and fixing receiving bracket are taken under the condition of
only enclosure structure and floor cushion. Finally, by continuously monitoring
the deformation and displacement of the underground diaphragm wall at the end
well, the entire process of risk monitoring and early warning can be realized
to ensure smooth shield receive, translate and lift out. Field application
results show the following: (1) The steel reinforcement, concrete, stone
excavation, and steel ring were reduced by 142 t, 644 m3, 1 680 m3, and 2, respectively, and the
construction period was shortened by 160 days. (2) The maximum deformation at
the end well of Dashadong station is 21.2 mm, which is less than the warning
value of 24 mm required in the specification. The maximum deformation rate is
1.5 mm/d, which is less than the warning value of 2.4 mm/d required in the
specification. The technology recommended can ensure safe shield receiving in
ultradeep foundation pit, guarantee the construction
period, avoid shield head felling, air leakage at the shield tail, and jamming
caused by a long time of shutdown.
LIU Dun
.
Application of Shield Receiving in Ultra-Deep
Foundation Pit Without Main Structure:
A Case Study of Dashadong Station of Gungzhou Metro Line 7
[J]. Tunnel Construction, 2023
, 43(S1)
: 506
-513
.
DOI: 10.3973/j.issn.2096-4498.2023.S1.060