Inner-support-free split mounting type steel formwork structure for small-section diversion tunnel

The utility model discloses an inner-support-free split mounting type steel formwork structure for a small-section diversion tunnel. A steel formwork is composed of a first formwork section, two second formwork sections, two third formwork sections, two fourth formwork sections and a fifth formwork section. The first formwork section, the second formwork section, the third formwork section, the fourth formwork section and the fifth formwork section are all arc plates, longitudinal ribs and transverse ribs are arranged on the inner circle faces of the formwork sections, bolt holes are formed in the edge longitudinal ribs and the edge transverse ribs of the formwork, and the adjacent formwork sections are connected and fixed in the mode that bolts are matched with the bolt holes. By the adoption of the structure, the steel die system is free of an inner supporting structure and can be flexibly assembled and disassembled on site, the stress principle of a needle beam type steel die trolley or a steel arch truss