Abstract:

The unreasonableness of the design method for total safety factor of composite lining tunnel established in the past is modified; the safety of different railway tunnels is analyzed; the method is compared with the support parameters of the Norwegian Q method; and the method is applied to the comparison and selection of tunnel crosssections of a tunnel. The results show that: (1) The total safety factor design method can provide a theoretical basis for the selection, quantitative design and overall optimization design of support components for primary support and composite lining. (2) The calculation results of safety factors of different railway tunnels by using the total safety factor design method are basically consistent with the actual construction conditions and the existing tunnel diseases. (3) The support parameters proposed by Q method in Norway applied to 350 km/h highspeed doubletrack railway tunnel in Grade Ⅲ and Grade Ⅳ surrounding rock in China can meet the safe and economic requirements, and that applied to 350 km/h doubletrack highspeed railway tunnel in Grade Ⅴ surrounding rock in China is with low safety factor; the durable bolts are conducive to giving full play to the supporting role of boltsurrounding rock bearing arch, thus reducing strength of the shotcrete layer and the secondary lining so as to improve the economic efficiency. (4) The total safety factor design method can be used for the precise selection of tunnel crosssection form and support parameters.

Key words: composite lining, total safety factor method, design method, Q method, loadstructure model, comparison and selection of tunnel crosssection