Deformation Analysis of Long-Deep Foundation Pit Excavation in Ningbo Metro Based Using Hardening Soil Small Strain Model

Ningbo soft soil predominantly consists of silt, which is characterized by significant thickness, high natural moisture content, low strength, and slow consolidation. When this soft soil is disturbed, it leads to surface settlement. This study examines a subway deep foundation pit in Ningbo by simulating and analyzing the entire excavation process using the finite element software PLAXIS 3D. The study investigates the lateral displacement of the supporting structure and surface subsidence trends. In addition, it discusses the effects of the diaphragm wall and supporting stiffness on the surrounding ground settlement. The findings indicate that increasing the stiffness of the diaphragm wall or support structure effectively reduces ground settlement during subway excavation. Furthermore, the study confirms that the proposed method for determining the HSS model parameters is suitable and can offer valuable insights for similar projects in Ningbo and comparable regions.