Synergistic Effects and Mechanical Properties of Adjacent Composite Pile-Sheet Wall in Embankment Widening Project

To address the technical challenges caused by terrain constraints in existing embankment widening projects, the innovative "Adjacent Composite Pile-Sheet Wall (ACPSW)" supporting system is proposed. This structure forms a com-po-site supporting system by adding parallel new pile-sheet walls among exist-ing pile-sheet walls. Combined with the engineering practice of the Lanzhou Hub Project of the Zhongwei-Lanzhou Railway, the numerical simulation method is adopted to systematically study the horizontal displacement of piles, distri-bu-tion characteristics of soil pressure behind the wall, and the collaborative bear-ing mechanism between old and new piles of the ACPSW structure throughout the construction process. The research reveals that under the cou-pled action of new embankment filling and train operation loads, the old and new pile-sheet walls can achieve collaborative deformation, forming a load dis-tribution ratio of 0.6:1 between old and new piles. The research results provide a design basis and engineering practice reference for new supporting structures in existing railway reconstruction and projects adjacent to existing railway lines.