Construction method for backfilling of underpass bridge culvert track bed

The invention belongs to the field of railway construction, and particularly relates to a construction method of backfilling of an underpass bridge culvert track bed. Before a main culvert is prefabricated, the slope ratio of an existing railway track bed is measured, when the main culvert is constructed, a wing wall, wing wall steel bars, concrete and the main culvert are casted on the top of themain culvert at the same time, the wing wall is same as the main culvert in antiseptic and waterproof arrangement, after the concrete strength of the main culvert meets the requirement, sandbags aremanually built and stacked, backfilling grouting is performed, a small vibrating machine is used for compacting grouting in advance, then, the main culvert is jacked to the place, after auxiliary project construction is completed, secondary backfilling of the wing wall and an existing roadbed transition section is prepared, drilling grouting is adopted at the wing wall and existing roadbeds at thetwo sides for reinforcing