Study on characters of supporting structure for deep foundation pit in rich-water soft stratum

Research purposes: The Neijiang Road Station of Shanghai metro is closed to the Huangpu River, with the poor engineering geological conditions, such as flowing mucky clay and 1m deep underground water. It is necessary to do the research on the internal forces and deformations of the supporting structure for the deep foundation pit of this metro station for providing the references to the similar works. Research conclusions: Taking the main deep foundation pit of this station as the engineering background, the introduction is given to the calculation process of the incremental method for the laminated wall and the internal bracing system by using the SAP84 finite element program. The research is done on the horizontal displacement of the underground diaphragm wall, the axis force of the steel bracing system, the vertical displacement of laced column and the settlement of the surrounding buildings during the excavation. The monitored result shows the measured horizontal displacements of the underground diaphragm wall are 44~71 mm, a bit bigger than the calculated values. The maximum measured axial forces of the steel bracing are about 64 to 80 percent of the maximum calculated value. The maximum heave value of the laced column is about 20mm.The analytical results indicate the deformation of retaining structure and the settlement of surrounding buildings can be effectively controlled if the steel bracing are installed in time and the floor concrete is casted as soon as possible.