Comments on Distance between Primary Support / Secondary Lining and Working Face of Inter-city Underground Railway Tunnels

In this article,the construction cycle time and construction model of Songshanhu tunnel on DongguanHuizhou inter-city railway are analyzed,and comparison and contrast is made between national railway tunnels and intercity railway tunnel. It is believed that the requirements specified in Tiejianshe No. [2010]120 are not applicable to the construction of inter-city railway tunnels. Proposals made are follows: 1) For inter-city railway tunnels in Grade Ⅵ surrounding rock,the distance between the primary support and the working face should be optimized from 35 m to 50 m,and the distance between the secondary lining and the working face should be optimized form 70 m to 85 m; 2) For tunnels in Grade Ⅴ surrounding rock,the distance between the primary support and the working face should be optimized from 35 m to 55 m,and the distance between the secondary lining and the working face should be optimized form 70 m to 90 m; 3) For tunnel in Grade Ⅳ surrounding rock,the distance between the primary support and the working face should be optimized from 35 m to 65 m,and the distance between the secondary lining and the working face should be optimized from 90 m to 120 m.