Large-span frame bridge jacking construction method for reinforcing existing railway lines based on combined temporary beams

The invention relates to the technical field of business line railway jacking construction, and particularly discloses a large-span frame bridge jacking construction method for reinforcing an existing railway line based on combined temporary beams. Comprising the steps of frame structure bridge prefabrication and back beam construction, rail stress relief, temporary buttress installation, steel sleeper beam installation, longitudinal beam installation, manual hole digging pile construction, transverse lifting beam installation, excavation and jacking, combined construction beam dismantling and line recovery. After the temporary buttresses are used for erecting the combined I-beam, operations such as manual hole pile digging and transverse lifting beam mounting can be carried out, the buckling rail beam pile digging process is omitted, the safety risk is reduced, and the construction period is shortened. When the manual hole digging pile is constructed, a construction channel is dug under a railway line, the n