“…The tunnel portal section is often affected by unfavorable terrain and geological conditions such as shallow burial depth, unsymmetrical loading and broken surrounding rocks, resulting in various damages such as excessive deformation, cracking, or even collapse during the construction process (Ye et al, 2012;Liu et al, 2015). Currently, there have been a large number of studies and reports on tunnel portal section, covering various aspects such as pre-reinforcement technology (Coulter and Martin, 2006;Xiao et al, 2016;, slope and face stability (Adam et al, 2014;Lei et al, 2015;Yuan et al, 2020;Zhou et al, 2021;Li et al, 2022), excavation methods and support (Miura, 2003;Yang et al, 2021), damage and treatment (Kontogianni et al, 2004;Cui et al, 2021), and others (He and Kusiak, 2017;Li et al, 2021a;Li et al, 2021b). However, the existing literatures has mainly focus on the condition of entering the tunnel, while relatively few studies have been carried out on the exit section.…”