Abstract: In order to effectively solve the construction quality problems such as insufficient thickness and strength of inverted arch, grouting and mud gushing from construction joints and upward arch, and ensure the safety of tunnel construction and operation, the tunnel scanning system is used to detect the excavation section of inverted arch of Zhaotong Tunnel project of ChongqingKunming Highspeed Railway, so as to ensure that the thickness of inverted arch meets the design requirements. And then the hydraulic selfpropelled integral inverted arch trestle is adopted to optimize the inverted arch arc template, realize sectioned and layered grouting and vibration, and improve the quality of concrete construction. The separate type steel formwork at the inverted arch end is used, the arcshaped belt at the inverted arch end is prelaid, and rubber back paste and medium steel plate embedded water stop belt are installed, which improves the quality of construction joint and reduces the occurrence of mud gushing in construction joint. The longitudinal drainage pipe and reverse water diversion pipe at the tunnel bottom are set to optimize the drainage design measures, which help to solve the problem of upward arch caused by water damage. Finally, the construction quality management measures for tunnel inverted arch are formulated and implemented. By adopting the abovementioned measures in the construction of Zhaotong Tunnel of ChongqingKunming Highspeed Railway, the thickness and the concrete strength of the inverted arch and the construction joint quality meet relevant design requirements.

Key words: railway tunnel, inverted arch quality, overcut/undercut inspection, concrete casting, construction joint, tunnel bottom waterproof and drainage