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| Study on the deformation features and resilience evaluation of tunnels in the construction of closely-spaced tunnels |
| LIU Jicheng1, ZHANG Xuefeng1, ZHEN Yuchao1, LIN Qingtao2*, YANG Chenghe2, LU Dechun2, DU Xiuli2
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1. China Construction Road and Bridge Group Co., Ltd., Shijiazhuang 050011, Hebei, China;
2. Institute of Geotechnical and Underground Engineering, Beijing University of Technology, Beijing 100124, China |
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Abstract The construction of closely-spaced tunnels, characterized by the limited clearance between adjacent drifts, posed significant challenges as the excavation of the subsequent tunnel could induce considerable disturbances that jeopardized the structural integrity of the pilot tunnel. Quantifying the resilience of the pilot tunnel-defined as its capacity to withstand construction-induced disturbances from the subsequent tunnel and to recover its functionality thereafter-was therefore crucial for ensuring safety during the construction of closely-spaced tunnels. This study investigated the Hankou Spiral Tunnels, a closely-spaced tunnel complex within the Xinjin Expressway project. Finite element models for nine distinct scenarios, encompassing three varying burial depths and three clear distances in a Grade V rock mass, were developed using the ABAQUS platform. The validity of the numerical model was confirmed through comparison with field monitoring data, specifically tunnel crown settlement and convergence deformation. Analysis revealed that crown settlement induced by subsequent tunnel excavation led to more pronounced functional degradation of the pilot tunnel compared to horizontal convergence, establishing it as the more appropriate indicator for resilience quantification. Based on the identified resilience evaluation indicators and structural performance evolution patterns, both resistance resilience index and recovery resilience index were calculated for all working conditions. The results demonstrated that increasing the pillar width from 10 m to 30 m under constant burial depth conditions enhanced the resistance and recovery resilience indices by 1.0%-9.0%, while reducing the burial depth from 150 m to 50 m under constant pillar width conditions improved these indices by 4.0%-12.0%. Generally, larger pillar widths and shallower burial depths resulted in higher resilience indices, with only the scenario combining 150 m burial depth and 10 m pillar width classified as medium resilience level, while all other configurations achieved high resilience level. This research provided a quantitative assessment framework for resilience-oriented design and construction of closely-spaced tunnels, offering valuable references for similar underground engineering projects.
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Published: 23 March 2026
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