Study On The Mechanics Behavior Of Railway Shield Tunnel With Double Lining

At present, Most of Highway and metro shield tunnels in our country used single segment lining. But from the usability feature, railway tunnel command additional secondary lining on overall line or just part line. For example, ShiZiYang tunnel of Guang-Shen-Gang railway passenger line construct double lining in the entrance and exit, Huangpu river tunnel even use double lining for all tunnel.This article is researching on railway shield tunnel with double lining. The following is introducing what we have done:(1) We have choose three double lining with different joints surface, which were resisting-compression double lining, resisting-shear and compression double lining and parts-resisting-bending double lining. According to calculate theory on double lining in the past, we pull in contact element which is on the basis of Mohr-Coulomb shear slide theory to distinguish and simulation different contact surface. Besides, we do some numerical simulation about them to test and verify theory in the past and enrich it.(2) With the way of indoor model test,we have done a lot of conventional test on single segment lining in different environment, like load under different earth pressure; different water pressure; different way of segment separation; different segment joint way. And we have done preliminary research on segment internal force affect by width and thickness. Taking into account of grouting leak in construction and ground weaken in service, we simulation this situation by model test, to pursue its affect to segment internal force. Through contrast, we have got the situation that leak or weaken take place in tunnel middle is the worst.(3) We propose the detailed way to simulate different contact surface and get data in model test. We do the same test on double lining as the single segment lining. As well as test the strengthen effect of secondary lining in tunnel middle weaken. In order to get the force feature of different double lining and the advantage to single segment lining. In addition, we summarize the optimization program of the secondary lining construction.(4) We preliminary discuss the affect of water pressure in double lining. in addition, we have done test on the damage of different double lining in the situation which tunnel middle is weaken and get the instability pattern of double lining. These prove that secondary lining is not only a usability element but also contribute to the structure durability.