Steel segment–anchor bolt (cable) structure for TBM tunnels under extremely intense rockburst conditions: Design method and field application

During the construction of deep‐buried railway tunnels, the issue of high in situ geostress is particularly pronounced, leading to frequent occurrences of rockburst disasters. In particular, the extremely intense rockburst is characterized by randomness, multiplicity, and uncertainty, which can easily cause significant damage to the main beam and support structure of the open tunnel boring machine (TBM). Due to the lack of systematic studies on rockburst characteristics and impact loads, support designs for rockburst‐prone tunnels are primarily based on empirical engineering experience. However, the existing support structures often fail to ensure construction safety. This study, based on a deep‐buried railway tunnel project, presents a detailed investigation into methods for determining rockburst impact loads and proposes a steel segment–anchor bolt (cable) support structure specifically engineered for TBM tunneling under extremely intense rockburst conditions. First, field records and statistics were used to summarize the spatial and temporal occurrence patterns of rockbursts. Six representative impact load modes and their action ranges were then defined for structural analysis. Then, the energy conversion relationship in the process of rockbursts was clarified, and the calculation formula of rockburst impact loads was developed using the kinetic energy theorem and the law of conservation of energy. To overcome the limitations of the existing support systems, a novel steel segment–anchor bolt (cable) structure was proposed, and a corresponding computational model was established. Subsequently, the selection of structural types under different sublevels of extremely intense rockbursts was determined. Finally, a field application was conducted to validate the feasibility and effectiveness of the novel structure. This study provides valuable insights for the construction of TBM tunnels under extremely intense rockburst conditions.