Construction control technology of a four-hole shield tunnel passing through pile foundations of an existing bridge: A case study

In dense urban building environments, various adjacent construction projects will inevitably occur during the large-scale construction of urban underground transportation projects. Based on an actual project, this paper conducted a practical study on the construction control technology of a four-hole shield tunnel passing through existing bridge-pile foundations over a short distance and proposed a micro-disturbed control technology system of “two-stage analysis method theoretical prediction + active control and passive protection”. The core content of the technology system included the following: 1) By introducing an additional ground loss ratio, a theoretical calculation method for predicting the deformation of pile foundations during the adjacent construction of a multi-line tunnel was established, which enabled the preconstruction prediction of the influence of construction on the adjacent structures. 2) A multi-coupled numerical model, which included tunnels, strata, and pile foundations, was developed to analyze the mechanical behavior of the pile foundations during the entire construction process. 3) Combined with practical engineering experience, the control measures of this project were implemented in terms of active control and passive protection. The deformation of the pile foundations was effectively controlled during the construction process, which certified that the proposed micro-disturbed control technology was reasonable and feasible.