Abstract:

The tunnels on Menghua Railway cross many strata with bad geological conditions, of which the construction difficulty and risk are high. On the basis of summary on construction technologies of railway tunnels in China and abroad, a series of applications and innovations have been carried out. 1) As a result of rapid ring closure for soft and weak surrounding rock, the CD method and CRD method are replaced by fullface method or bench method. 2) The primary support quality is improved; and "two close", i.e. grid steel frame of primary support closes to tunnel face and ring closure of primary support inverted arch closes to lower bench, is carried out. 3) The advanced geological prediction is improved; and monitoringbased informatized platform is established. 4) The parameters of system anchor bolt, steel frame and secondary lining are optimized by scientific test to guarantee the structural stability. 5) The mechanization of the tunnel construction, i.e. wet spray manipulator, selfpropelled inverted arch long trestle, horseshoeshaped shield, precutting machine and improved secondary lining trolley, is carried out. 6) The engineering alteration is carried out in accordance to actual conditions so as to rationalize engineering cost and improve the management effect of contract and investment. The discoveries and innovations of Menghua Railway have successfully guaranteed the construction safety and quality. 

Key words: Menghua Railway, tunnel engineering, excavation method, primary support, advanced geological prediction, monitoring, construction equipment, engineering alteration, engineering cost