Abstract: In order to obtain a deeper understanding of the deformation characteristics of the retaining structure and the adjacent buildings of deep foundation pit of metro station caused by deep excavation in soft soil, systematic monitoring and result analysis of deep foundation pit engineering of a metro station in deep soft clay area were carried out. It was found that grooving of diaphragm wall will cause lateral displacement of adjacent soil. The maximum lateral displacement of soil accounts for about 20% of the lateral displacement of soil during excavation of foundation pit. The average values of maximum lateral displacement of the retaining wall on the south side (namely the side of the pile foundation buildings) and the north side (namely the side of the shallow foundation buildings) during soil excavation were 0.091% He and 0.120% He, respectively. When the value of y/He ( y is the distance between vertical continuous wall direction and diaphragm wall, and He is the excavation depth) is less than 0.92, the magnitude of the settlement and differential settlement induced by excavation was relatively larger. The settlement of the ground surface was close to that of the shallow foundation settlement, while the settlement of the pile foundation was obviously less than that of the shallow foundation building among which the rock-socketed pile foundation building had the smallest deformation value. Both the shallow foundation buildings and pile foundation buildings were affected by spatial effect which was more obvious when the value of x/He (x, the distance from the corner in the longitudinal direction) was less than 1.5. When the value of x/He was greater than 2.0, the soil deformation near the adjacent buildings and retaining structures approached to a plane strain state.

Key words: metro station, deep excavation, buildings, settlement, spatial effect