Numerical analysis of vibration induced by bench blasting with different blasting parameters of rock tunnel excavation

Abstract

Blasting is an important excavation method, which may induce harmful effects on surrounding rock masses and adjacent structures. It is essential to study the influences of various blasting parameters on vibration, which can be categorized as the single-cycle footage, blasthole spacing, single hole charge, and cavity caused by upper bench blast. In this paper, the vibration of adjacent tunnel and bench blasting excavated tunnel in Guangzhou metro are studied. The in-situ tests and numerical studies are carried out in sequence, and the material models and parameters of numerical model are valued according to geologic survey and monitoring results. The numerical results almost equivalent to field test data verify the accuracy of material models and parameters. What’s more, numerical models with different single-cycle footage, blasthole spacing, single hole charge, and bench blast are calculated and analyzed respectively, which showed that bigger single-cycle footage, smaller blasthole spacing, and more single hole charge all lead to greater vibration and quicker vibration attenuation. Besides, the cavity caused by earlier blast work limit blasting shock to a great extent, which is the reason why upper bench blast induces more vibration of adjacent tunnel than lower bench blast. The research herein is carried out to improve Sadovsky formula and provide theoretical foundation for improving the stability of tunnel blasting excavation.