Abstract:

Many Metros are building in the first terrace of the Yangtze River in Wuhan, China. During the backfill construction of Metro station pit, support replacement will delay the construction schedule of the major structure construction. In this regard, a nonsupport replacement scheme is proposed. In this paper, the deformation and bending moment of diaphragm wall, settlement of ground surface, and regulations of axial stress of support structures are analyzed under the conditions of underground water level variation and that support replacement and nonsupport keplacement. A case of a Metro station pit in Wuhan is taken as the research background. The comparison and contrast between the monitoring data and theoretical calculations shows that: 1) Water pressure on the underground diaphragm wall reduces as water level drops; 2) The horizontal displacement of diaphragm wall and ground surface settlement behind the diaphragm wall increase by 10% compared to those in the original design; 3) The bending moment of the diaphragm wall and axial stress of the support structure can meet the original design requirements, and the optimized support replacement scheme is feasible. The water level outside the pit and the deformation of the diaphragm should be focused on when nonsupport replacement scheme is used.

Key words: Metro, foundation pit, support optimization, first terrace of Yangtze River