Construction method for improving roadbed backfilling quality after removal of frame structure of existing line

The invention relates to the construction of a roadbed backfill project after a frame structure of an existing line is removed, in particular to a construction method for improving roadbed backfill quality after the removal of frame structure of the existing line. The 16mD type auxiliary beams are adopted on the two sides of the line to reinforce the railway, the reinforced concrete protection piles are adopted at the four corners for protection, overhead reinforcement protection is conducted on the line, and safe driving is guaranteed. The lower part of the frame bridge roadbed cavity part is backfilled by adopting AB group materials firstly, then C20 rubble concrete is used for backfilling, and railway ballast is backfilled when the distance between the lower part and the designed rail bottom is 0.8 m. Finally, grouting is conducted on the outer side of the backfilling range by 2 m, and it is ensured that the rubble concrete for backfilling and the roadbed of the loose part of the existing roadbed are stabl