A method for analyzing surrounding rock unloading in tunnel blasting excavation based on complex variable theory
Year: 2026
Type: article
Abstract: Accurate characterization of the surrounding rock stress field and quantitative assessment of excavation-induced unloading effects are critical to guarantee the safety and stability of deep tunnel construction. To tackle this challenge, this study solves the mapping function via a trigonometric interpolation iterative approach incorporating mixed convergence constraints. The theoretical solution for the surrounding rock stress field subjected to partially uniform support reactions along the excavation boundary is derived using series expansion and Cauchy’s integral formula. Validation results demonstrate that the proposed mixed convergence iterative scheme reduces the iteration number of the mapping function by more than 50% and controls the global error within 3% compared to the single convergence approach. With a reasonable number of series expansion terms, the discrepancy between the theoretical predictions and the actual given values is approximately 8%. A hybrid dynamic-static method coupled with numerical simulation is adopted to evaluate the unloading effects induced by blasting excavation on the surrounding rocks under high in situ stress conditions. The results show that overbreak exceeding 45 cm intensifies the local unloading effect, with its influence exceeding 50% of that caused by blasting disturbance. Owing to stress concentration, the stress at the arch foot and arch waist can reach 2-3 times the initial in situ stress.
Language: English
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7202123786