Research on Shield Tunnel Attitude Adjustment Scheme Based on Pipe Segment Construction Floating Control

At present, there is a lack of theoretical and quantitative analysis on the influence of shield tunnel posture on the upward floating phenomenon of shield tunnel segments under synchronous grouting, which makes it difficult to provide a reasonable shield tunnel posture adjustment plan for construction sites. By considering the influence of shield machine attitude on the shield-tail segments, based on the Euler beam theory, the Pasternak two-parameter foundation model, and other related mechanical theories, an analysis model for the influence of shield tunnel segment uplift under synchronous grouting is established, and the uplift phenomenon, deformation, and internal force responses of shield tunnel segments under different shield attitudes are analyzed. The results show that: Reasonable adjustment of the shield attitude can control the uplift phenomenon of segments during construction to a certain extent. The vertical position of the shield machine can be appropriately adjusted downward, and the pitch angle can be adjusted so that the tail of the shield machine rotates downward, which can alleviate the uplift phenomenon of the segments and reduce their internal forces. Unreasonable adjustment of the shield attitude will not only aggravate the uplift phenomenon of the segments but also significantly increase their internal forces. In actual projects, in order to control the uplift phenomenon, the vertical position of the shield machine can be appropriately adjusted downward, and the pitch angle of the shield machine can be appropriately adjusted to keep the tail of the shield machine rotating downward. After adjusting the shield attitude according to the research conclusions of this paper, the uplift phenomenon of the segments in the referenced project was alleviated. The research results can be used to guide the quantitative adjustment of shield tunneling posture when controlling the upward movement of construction pipe segments.