Taking the reinforced concrete frame overpass of Longhai Railway and Xikang Railway under-passing Hedi East Road,Baqiao District,Xi an City,as an example,this paper sums up some critical procedures such as the line consolidation and jacking construction and some measures for security in the jacking construction technology for existing railway under-passing the Large-frame bridge.

The technology of line reinforced by the temporary beam in the D pattern and container bridge jacking has been widely applied.

On roadbed strengthening in the sixth speedup of Jing-Guang line;

This thesis, as a part of a research project sponsored by Beijing Railway Bureau titled “The design proposal of the technical equipment for strengthening the roadbed against hazards in speed-lift area”, has completed the optimized design of a vibratory extracting-driving piling machine for roadbed strengthening.