Monitoring analysis of influence of extra-large complex deep foundation pit on adjacent environment: a case study of Zhengzhou City, China

Abstract

Extra-large complex deep foundation pit excavation has an impact on the surrounding environment. The deformation characteristics of deep foundation pits were investigated during excavation, according to the temporal and spatial variations in displacement, using long-term on-site displacement monitoring. The results show that the deformation characteristics of the supporting structure and surrounding buildings can be divided into four stages: earth excavation, cushion construction, internal support removal and cushion completion. In the stages of earthwork excavation and support removal, the settlement deformation of the supporting pile roof, lattice column and adjacent ground is large, and cushion construction has a weakening effect on foundation pit deformation. In the stages of earthwork excavation, cushion construction and internal support removal, the nonuniform settlement between adjacent lattice columns increases the lattice column deformation, and the deformation of the foundation pit tends to be stable after the completion of the internal support. The foundation pit excavation mainly affects the settlement deformation of the adjacent pipe gallery, and its deformation increases rapidly in the early stage of earthwork excavation. Moreover, the influence degree of foundation pit excavation on the surrounding environment decreases with increasing distance from the excavation area.