Abstract:

Because the metro tunnel is located near the surface ground, the cross-section of the tunnel has a great influence on the efficiency of the design, construction, use and operation of the subway tunnel, especially the impacts on the stability, the environmental landscape of the surface structures. Nowaday, circular metro tunnels are the most popular shapes used in urban underground transportation and metro system when Tunnelling Boring Method (TBM) is used for the tunnel excavation. However, circular tunnels have a small space utilization ratio. It makes to the excavated cross-section much larger than the used cross-section, and reducing the project efficiency. With the development of material and tunnel structure, non-circular tunnels are now common, and their cross-section permits to improve the underground space use efficiency. The sub-rectangular section metro tunnel is being studied and tested a lot in recent times because they satisfy two criteria at the same time: the load carrying capacity of the tunnel lining and the utilization useful factor of large cross-section. However, the calculation of the tunnel lining of this type by analytical method is very complicated and there is no solution for the above shape. The paper present the influence of the metro tunnel shape on the lining forces is considered by using the numerical simulation by Plaxis2D software. A parametric study was performed in order to highlight the effect of some parameters of the characteristic of depth of metro tunnel, thickness of metro tunnel lining on the structural forces produced in the sub-rectangular metro tunnel lining stability in line 6 of metro tunnel project in Ho Chi Minh City