Study on waterproof and drainage techniques of tunnels based on controlling drainage

In order to solve some technique problems of waterproof and drainage of tunnels based on controlling drainage,model tests,numerical simulations and site investigations were performed by use of two cases Longtan Tunnel and Baiyun Tunnel.Key issues including water plugging types,waterproof board spreading methods,drop of external water pressure and lining design for resisting hydraulic pressure,etc.were studied,thus the composite waterproof and drainage system to control drainage were put forward,including grouting sphere for water plugging,primary support,grid sysytem for waterproof and drainage and lining to resist hydraulic pressure.