Study of contact pressure between primary lining and secondary lining for tunnels of passenger dedicated lines

Abstract

To systematically study the mechanical properties of the secondary lining for tunnels of the passenger dedicated lines(PDL), in-site monitoring is used to measure the contact pressures between the primary lining and the secondary lining for some typical tunnels of different Lines, such as Guiguang Line, Lanyu Line and Jinghu Line. According to the research, the contact pressure reaches its maximum value at the moment when the tunnel lining trolley is removed. The load acting on secondary lining is the actual deformation pressure, which is totally different from the loose pressure prescribed in Chinese tunnel criteria. The safety factor for secondary lining under the measured load is higher than that under the criteria load and satisfies the safety requirements. It is therefore possible for the primary lining to sustain the entire surrounding rock pressure with the help of necessary auxiliary method and suitable installation time. The result given in this research enhances our understanding towards the mechanical characteristics of secondary lining for the PDL tunnel and it will be helpful for secondary lining design.