Abstract:
When tunneling in soft rock stratum with significant time-dependent deformation characteristics, the construction interruption caused by force majeure may generate adverse effects on tunnel linings, resulting in the increase of tunnel construction risk. Therefore, it is a very important task to accurately evaluate the influence of construction interruption on the long-term stability of surrounding rocks and linings. In order to investigate the interaction mechanism between surrounding rocks and linings, the three-dimensional tunnel excavation problem is equivalent to a two-dimensional plane strain one by using the stress release coefficient. The improved expression is established, which is based on the classical stress release coefficient expression in the negative exponential form and takes the construction interruption into account. Furthermore, by using the generalized Kelvin model describing the time-dependent behaviour of surrounding rocks, the analytical solution for temporal and spatial tunnel deformation is derived, where the construction interruption and delay installation of lining structures are considered. Through its application in Rongjiawan tunnel of Zhengwan high speed railway, the theoretical derivation provided is well verified. A parametric investigation is carried out based on the previous analytical solution, including duration and start time of construction interruption and excavation rate. It can be found that the lining pressure caused by the tunnel face advancement contributes about 17.3% of the total lining pressure. The duration and start time of construction interruption exhibit a significant influence on the developments of tunnel displacement and lining pressure, but do not show obvious influence on the final tunnel displacement and lining pressure. A greater excavation rate before the construction interruption leads to a decreasing rock pressure born by the tunnel face. When the stress release coefficient value reaches 0.8, the influence of the excavation rate after the excavation rate can be basically ignored.