Abstract: Technical difficulties, such as difficult laying, multiple weld joints, easy falling, and difficult quality control, are always present in the waterproof and drainage construction of superlarge tunnel structures with spans greater than 30 m. Therefore, a new waterproof and drainage system, composed of a ring and longitudinal drainage system, composite geomembrane, highelastic film waterproof layer, selfcompacting concrete, and joint waterproofing, is proposed. Furthermore, the design composition, layout, and maintainability design of the ring and longitudinal drainage blind pipe, concaveconvex drainage plate, and drain pipe are introduced from the perspective of drainage. From the perspective of waterproof, the dual characteristics of isolation and antiseepage of composite geomembrane, performance index and spraying design of sprayed membrane waterproof layer, waterproof design of the selfcompacting concrete structure and joint, and construction key technologies are introduced. The practice results indicate that the proposed waterproof and drainage system can be applied to the superlargespan tunnel structures, resulting in safe and reliable construction, high work efficiency, and good waterproof effect.

Key words:  , superlargespan tunnel, waterproof and drainage, membrane waterproof, composite geomembrane, selfcompacting concrete