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A unified design model for estimating tunnel performance considering multiple excavation stoppages

Wu Kui, Xing Chenzhe, Yang Yuezong, Shao Zhushan, Zhao Nannan, Chu Zhaofei

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 4

art. e260, 1--14

In tunnel construction, excavation stoppages are often encountered due to many irresistible factors. This study reveals the influence mechanism of excavation stoppages on tunnel mechanical response by using mathematical analytical method. Firstly, the mathematical expressions for stress release coefficient considering multiple excavation stoppages are redefined and provided, based on the previous stress release coefficient in the negative exponential function form. Secondly, the mechanical model of a deep circular lined tunnel considering excavation stoppages is established, and the unified analytical solutions for tunnel displacement and liner pressure during the unlined and lined (excavation and excavation stoppage) stages are provided, respectively. Furthermore, the proposed solutions are able to capture the average tunnel deformation and liner pressure in Rongjiawan tunnel (an excavation stoppage took place) and agree well with the numerical results. Finally, a parametric investigation is performed, including the influences of starting time and duration time of excavation stoppage, excavation rate and liner installation time. Results show that both the final tunnel displacement and liner pressure are unaffected by starting time and duration time of excavation stoppage. However, their convergence rates are significantly affected by these two excavation stoppage factors. A higher excavation rate before stoppage causes a larger tunnel displacement and a smaller liner pressure. The influence of re-excavation rate is too low to be paid attention. A higher liner pressure can be induced by an earlier liner installation. The findings in this study are helpful for the evaluation of excavation stoppage-caused influence in tunnels.