极软千枚岩隧道大变形力学机理与施工措施优化OA

To address the severe large deformation issues in tunnels constructed through extremely soft phyllite strata,this study integrates field monitoring and numerical simulation to investigate the deformation mechanisms of the surrounding rock and proposes a novel support system.Monitoring results reveal significant spatiotemporal asymmetry in deformation,with the cumulative displacement of the left haunch reaching 575 mm(71.6％higher than the right haunch).The deformation process exhibits a dual-phase evolution:rapid initial stress release(80％of total deformation within the first 30 days)followed by a mid-term secondary disturbance(rate resurgence to 10 mm/d at 40 days).A FLAC3D-based numerical model effectively replicates these patterns,demonstrating less than 10％average deviation from field data,and thus thereby validating its capability to capture high geostress-soft rock interactions.A"flexible-rigid collaborative phased control"support system is developed,incorporating sliding steel arch supports,asymmetric bolt densification and delayed secondary lining installation.This approach reduces total deformation by 40-50％and mitigates asymmetric displacement differences to below 30％.The proposed methodology establishes a systematic"deformation release-stress redistribution-structural reinforcement"framework,resolving the inadequacy of conventional rigid support systems under extreme deformation conditions.