Deformation of deep and large foundation pit in soft soil of Fuzhou Subway

Abstract

In order to study the deformation law of deep and large foundation pits in the soft soil layer of Fuzhou, 22 lines of 2#, 5#, and 6# lines of the rail transit system in Fuzhou area are covered by 1 m underground continuous wall or 850SMW method piles + multi-layer. The measured data of the inner-supported long-shaped subway foundation pits were statistically analyzed and compared with the research results of similar projects at home and abroad. The results show that (1) the maximum horizontal displacement δhm of the continuous wall of the subway pit is 0.078–0.15% Hm, the average value is 0.118% Hm; (2) the maximum horizontal displacement point of the retaining structure is located at a distance of about 8 m; (3)the maximum settlement value δvm is in the range of 0.057–0.124% Hm, and the influence range is about 4.5 Hm; (4) the range of δvm/δhm of the foundation pit of the subway station is 0.13–1.07, and the average value is 0.96; (5) the range of the column bulge value δcu of the station foundation pit is 0.05–0.11% Hm. The research results of this paper can provide reference for the design and construction of other subway (3#, 4#, 7#, 8#, and 9#) stations and similar foundation pit supporting structures in Fuzhou.