Abstract:  Tunnels constructed by mining methods always have many problems such as voids behind the lining structure and insufficient thickness and strength of secondary lining. Accordingly, a novel prefabricated segment for the tunnel arch is proposed. Based on a doubletrack tunnel with a speed of 350 km/h, a series of design parameters of prefabricated tunnel lining at tunnel arch are studied using numerical calculation and analysis methods. Main conclusions are drawn as follows: (1) The integral prefabrication form of arch fabricated lining in the circumferential direction is proposed. Considering the theoretical calculation results, traffic safety analysis, transportation and assembly capacity of mechanical equipment, bearing capacity of arch lining, etc., the structural dimensions and reinforcement design parameters of arch segment circumferential chord length of 8.6 m, longitudinal width of 2 m, and lining thickness of 50 cm are determined. (2) The arch preproduction tube slice is connected with each other by bolts, which also be connected with castinplace sidewall by Ltype tenon joints. Meanwhile, the dimensions design parameters of the tenon joints are proposed. (3) To ensure the smooth installation of arch segments, the construction error should be considered for the tenon joint of castinsitu sidewall, and an installation space shall be reserved between the arch segment and the primary support. After the segment is installed, the space between surrounding rock and segment shall be filled and compacted by longitudinal grouting at the back. The prefabricated lining at tunnel arch  has been successfully applied to the Hujiagou tunnel in Chongqing, China, and the overall implementation effect is good.

Key words: railway tunnel, mining method, tunnel arch; prefabricated , lining, structure type; joint form, segment size