ABSTRACT
The excavation of the tunnel entrance section caused stress release, the surrounding rock burial depth of the tunnel entrance section was shallow, and the geological structure conditions were complicated, which made the entrance section vulnerable to the threat of collapse and deformation and damage, and adversely affected the safe transportation. Therefore, it is necessary to analyze the stability of the tunnel roof and the stability of the tunnel body and the interaction between them during the construction process. In this paper, combined with the National Highway 208 project, the above problems are studied through numerical simulation. A three-dimensional numerical simulation model was established for the tunnel entrance section of the project, and full-face excavation (drill and blast method) and partial-section excavation (CD method) were used for dynamic construction simulation, and the tunnel surrounding rock and stress field under the two construction methods were compared and analyzed. Displacement field change law and its stability are evaluated, and the construction method that has little influence on the stability of the tunnel entrance is selected.
