Abstract: In response to the problems existing in conventional steel arches, the use of a steel arch with scalable joints is proposed, that is, adding scalable joints and supporting arms to the ordinary steel arch. The application test of scalable steel arch frame is conducted in the Donggangshan Super-Long Tunnel, and a comparative analysis is performed on deep displacement of surrounding rock, internal force of steel arch, surrounding rock pressure, and crown settlement of the scalable steel arch support section and the ordinary steel arch support section. The results show that the scalable joint steel arch frame provides timely support for the surrounding rock. Compared with the ordinary steel arch frame, it can more effectively constrain the deformation of surrounding rock. For the surrounding rock with large deformation, it can effectively limit the early development of the loose area of surrounding rock, and is suitable for support in weak and fractured surrounding rock areas.