roadbed splicing;  expansive soil;  centrifuge model testing;  Uneven settlement

Old road widening projects often involve the problem of combining new and old roadbed. Combined with the Hefei railway hub renovation project, the influence of subgrade height, splicing step section size, new subgrade slope rate and other factors on the safe operation and subgrade stability of new and old routes was studied by centrifugal model experiment, and the new and old subgrade splicing technologies suitable for expanding land areas were proposed, including design methods, construction processes, control standards, etc. It will provide theoretical support and demonstration reference for similar reconstruction and expansion projects, which has great guiding significance and application value for the construction of railway reconstruction and expansion projects.