Abstract:

Secondary lining crowns of railway tunnels constructed by the mining method have many defects, such as hollows, insufficient thickness, cracks, and falling blocks. Accordingly, a case study is conducted on the Hujiagou tunnel of the east ring line of Chongqing railway hub, and the castinplace lining is replaced by a prefabricated one. Furthermore, arch lining prefabrication, sidewall construction using a highprecision cantilever, prefabricated lining transportation, and prefabricated lining assembly equipment are studied. Moreover, technical issues faced in prefabricated lining construction, including the joint straightness adjusted by highprecision lining formwork jumbo and sidewall cantilever steel skeleton stabilized by entirering universallength positioning reinforcement, are resolved, forming a complete set of new prefabricated lining assembly technology. The field application reveals the following: (1) The prefabricated lining construction technology of the prefabricated arch lining + castinplace sidewall is feasible, which can effectively avoid the quality defects of tunnel arch constructed by the mining method and improve the quality of tunnel arch lining. (2) The new prefabricated lining adopts the Ltype and large spherical joints, and the construction quality is easier to control and assemble by the large spherical joint than the Ltype joint. (3) A series of techniques, such as speciallymade steel mold with high precision, highprecision cantilever formwork trolley, and secondary refined adjustment of sidewall cantilever during concrete casting, are adopted to ensure the joint construction accuracy and meet assembly requirements. (4) By analyzing the data monitored for stress and deformation of the lining structure, the stress and deformation law of internal force of tunnel lining structure is obtained. (5) The new prefabricated lining construction technology has a high mechanization degree, which can guarantee the stability and safety of the structure during construction.