Abstract
When large deformation of the tunnel occurred in the swelling rock, the large deformation treatment will not only greatly delay the construction time, but also lead to instability or even collapse of the tunnel. Selecting the reasonable timing for large deformation initial support replacement can solve this problem effectively. Based on the LiRang tunnel, the deformation and stress of the tunnel in anhydrite were analysed by FLAC software after excavation. Then replace the deformed first liner at different vault settlement value. The displacement and stress of surrounding rock were analysed when the model reaches equilibrium state again. The results showed that stress concentration at the arch wall and arch foot of the tunnel, and the stress release at the vault and invert is very large after excavation. If the large deformation was treatment when the crown settlement of the tunnel reaches 90% ~95% of the final predicted settlement value, the tunnel deformation and the final stress state could be in a small value. This study can provide a reference for the treatment of large deformation in the swelling rock tunnel.
Highlights
Swelling rock is a kind of rock that the water content and the volume increases with time after the physical and chemical reaction with water
The hydraulic conductivities in the rock mass around the tunnel can increase greatly due to tunnelling; it can be increase by up to 6 orders of magnitude compare to the intact rock [1, 2]
The tunnel engineering hazards caused by swelling rock increased sharply with the rapid development of highway and railway construction
Summary
Swelling rock is a kind of rock that the water content and the volume increases with time after the physical and chemical reaction with water. The usual method is to apply temporary support to reinforce the deformed first liner, replace the deformed first liner when the deformation of the tunnel gradually decreases and tends to be stable [10]. It needs a long period to the rock mass getting stable, for example, the deformation rate become less than 3.0mm/d. This will seriously delay the construction schedule. It is necessary to study the timing of replacement of large deformation, so that the deformation of tunnel can be the smallest during the replacement process and the replacement, and the stress become the lowest when the support and the surrounding rock reaches equilibrium again
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
