Influence of the pillar width on the construction sequence of twin tunnels
Influence of the pillar width on the construction sequence of twin tunnels
Twin tunnelling has become frequent in large cities given the lack of space at ground surface and the need to have an adequate and efficient transportation network. In these systems the tunnels are usually built sequentially, i.e. with a considerable lagging distance between the tunnel excavation faces, though simultaneous excavation is also possible with the advantage of speeding up the construction and anticipate the operation stage. Regardless of the construction sequence adopted an important factor that affects the behaviour of both tunnels and the interaction effects between them is the pillar width. In order to assess its influence on the construction sequence of side-by-side twin tunnels a series of 2D finite element analyses were carried out. The numerical results show that the construction sequence has a residual impact for pillar widths higher than two times the diameter of the tunnels. However, for smaller distances a considerable interaction is observed, with the simultaneous excavation having a detrimental effect on the surface ground movements, while the sequential excavation induces considerably higher lining forces on both tunnels.
Antonio M G Pedro; C. D. Grazina Jose; J. Almeida e Sousa
10th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2023)
10. Tunnelling and mining applications
https://doi.org/10.53243/NUMGE2023-6
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