To explore the stress characteristics of the anchor bolt support in small-section TBM tunnels and assess the rationality of the support parameters, a study was conducted based on the Tongcheng Pumped Storage Power Station’s self-flow drainage tunnel project in Anhui Province. The study employed theoretical analysis, finite element method, and on-site monitoring to investigate the stress characteristics of the anchor bolt support structure. The results show that: the axial force values obtained by the finite element method and on-site monitoring both have the maximum axial force at the deepest part of the anchor at the arch. The maximum axial force calculated by the rock mass mechanics method occurs at the neutral point of the anchor. The displacement of the surrounding rock obtained by the three methods all has the maximum displacement on the surface of the surrounding rock, and the displacement of the surrounding rock is the smallest at the deepest part of the anchor. Further based on the finite element calculation results, it is concluded that for small-section TBM tunnels, the anchor axial force and surrounding rock deformation are both small, and optimization suggestions are put forward to reduce or cancel the anchor support of small- section TBM tunnels. The research results can serve as a reference for optimizing anchor bolt support parameters in similar engineering projects.
TBM, Bolt support, Structural analysis, Numerical simulation, Parameter optimization
