摘要
The construction of new tunnels induces additional/unloading pressures on existing tunnels,subsequently affecting structural integrity.To assess tunnel response,a full-scale multiring test was conducted,simulating water/soil and additional/unloading pressure from a new undercrossing tunnel.Key parameters analyzed included additional/unloading pressure,tunnel axis distance,longitudinal forces,and loading levels to evaluate structural deformations and joint behavior.Results showed that additional/unloading forces significantly impact structural ring convergence during tunnel crossing stage.These forces vary nonlinearly with distance from the crossing point,but their influence is linear.Further,joint opening and dislocation not only depend on external load but also on the staggering effect and segment geometry.Reducing the tunnel axis distance meaningfully upsurges unloading forces,leading to higher strains at joints and the segment body.Longitudinal force,directly proportional to the staggering effect,reduces structural deformations;for instance,even a 1%force mitigates up to 32.05%joint dislocation.Lifecycle analysis revealed the tunnel crossing stage is far more vulnerable than the construction/operation stage,and tunnel axis distances of twice or more of the diameter can be considered safe.This study provides practical insights for engineers to mitigate risks during tunnel crossings and enhances safety guidelines for life cycle management.
基金
supported by the National Natural Science Foundation of China(Grant No.52478409)
Shanghai Sci-tech Co-research Program Qualification Project(No.23DZ1202903).
