Research on ground deformation induced by large caisson construction at the Zhuchong pumping station in Xinyang,...

The caisson method is typically employed in foundation pit projects characterized by complex surrounding structures and challenging engineering geological conditions. The sinking process involves complex soil-structure interactions, particularly the sidewall friction between the caisson and the surrounding soil strata. This friction is a critical factor, as it not only determines the feasibility and safety of the sinking operation but also influences the pattern and magnitude of surrounding ground subsidence. This study aims to explore the mechanism of sidewall friction between the caisson and strata and its direct impact on controlling the sinking process and mitigating surrounding subsidence. The analysis is based on the large caisson engineering of Zhuchong Pump Station, located in Xinyang City behind the Chushandian reservoir. By conducting a numerical simulation of the sinking process and analyzing measured data from on-site subsidence monitoring points, this research reveals that the caisson induces a parabolic-shaped subsidence curve in the surrounding ground surface. The magnitude and extent of ground subsidence around the caisson increase with greater sinking depth and with proximity decreasing distance from the sidewall. The study further demonstrates that sidewall friction significantly influences ground subsidence. Specifically, lower friction in the initial sinking phase results in noticeable ground uplift due to reduced constraint on soil displacement. Conversely, higher friction leads to increased ground subsidence as the sinking depth progresses. The study reveals that the influence pattern of friction between the caisson sidewall and the surrounding soil on ground surface subsidence, and lower friction would result in pronounced ground uplift due to reduced constraint on surface displacement during the initial sinking phase, and higher friction would increase ground subsidence as the caisson sinking depth increases. The findings of this research may help provide a technical reference for subsidence control in similar large-scale caisson projects.