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Computational study demonstrates that crossing angle and clearance distance dominate tunnel resilience during twin shield undercrossing, highlighting optimal spatial design for structural safety.
The disturbance effects induced by twin shield tunnel undercrossing significantly compromise the lining performance of existing tunnels and threaten operational safety. This study systematically evaluates lining resilience under cumulative disturbances and establishes a theoretical basis for protection design. First, 15 representative cases with varying spatial relationships (distance S and angle α between new and existing tunnel and distance L of new twin tunnel) were analyzed, and four key indicators were adopted to characterize the response mechanisms. Then, the grouting element volume expansion method was employed to simulate secondary grouting after each undercrossing, enabling performance restoration. Finally, tunnel resilience (segment and overall) was quantified by adopting the characteristic of tunnel settlement as primary indicators and utilizing the entropy weight method to determine their case-specific weights. The main findings are as follows: The rank of effect on the overall resilience is α > S > L . The minimum segment resilience improvement rate from 30° to 90° drops 27.13% ( S = 0.5 D ), 23.77% ( S = D ), and 19.81% ( S = 1.5 D ), the angle is most critical at small clear distances. Further, modifying S is more effective and economical than L for resilience enhancement.
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Zhang et al. (2026) studied this question.
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