Abstract: In response to the problem of deformation of deep foundation pit excavation in soft soil areas, this paper takes a deep foundation pit located in Tianjin as the research object. Based on the ABAQUS finite element model, the horizontal and vertical deformation of the retaining wall during the excavation process, as well as the settlement deformation of the surrounding soil and adjacent buildings are analyzed. The finite element analysis results are compared to the field monitoring results, obtaining the deformation characteristics of the deep foundation pit excavation and its influences. Researches indicated that the maximum horizontal displacement of the retaining wall is mainly concentrated in the excavation surface, and the horizontal deformation of the positive angle is about twice that of the negative angle.The vertical deformation of the retaining wall has a significant spatial effect, which has good linear relationship with the length of the wall. The maximum rebound value occurs at the external corner of the foundation pit. As the excavation depth increases, the settlement mode of the soil around the foundation pit changes from a triangle to a groove shape, and the settlement value and range increase with the increase of the distance from the pit angle. In response to the problem of uneven settlement of adjacent buildings caused by excavation of foundation pits, grouting reinforcement measures could reduce settlement deformation by about 30%, confirming the effectiveness of grouting protection measures. This study can provide reference for similar engineering design and field construction.

Key words: deep foundation pit excavation, field monitoring, numerical simulation, deformation characteristics, impact on environment