Reinforcement Effect of Horizontal Bottom Sealing of Deep Foundation Pit in Water-rich and Deep Sand Layer

Abstract

For deep foundation pit with rich water and deep sand layer, construction safety problems such as water and sand gushing may occur during excavation. Base sealing with well point dewatering is a common measure to ensure the safety of foundation pit excavation. This paper is based on an open-cut construction project of a metro station in Taiyuan. The fluid-structure coupling analysis and comparison of foundation pit excavation process were carried out by using finite element software. Combined with the field inspection data, the influence of different bottom sealing forms and dewatering on the deformation of foundation pit was studied. The results show that the bottom sealing reinforcement can effectively reduce the maximum lateral displacement of diaphragm wall, the maximum surface settlement, and the maximum uplift of basement. The amount of deformation is reduced by about 50% compared with that without reinforcement. With the same reinforcement thickness, the reinforcement effect is better starting from the basement. The new support system composed of bottom sealing reinforcement zone and diaphragm wall can control the seepage of groundwater and the deformation of foundation pit well with the well point dewatering.

Keywords

• deep foundation pit
• bottom sealing reinforcement
• sandy soil layer
• grouting reinforcement
• foundation pit precipitation