Dynamic Response Analysis of Mountain Tunnel Under Blasting Vibration

Tunnel drilling and blasting will cause large vibrations in the surrounding rock and structures. This vibration effect weakens the rock, greatly threatening the surrounding rock’s structural integrity and the safety of tunnel construction. Based on an analysis of the status quo of rock blasting, this study performs on-site monitoring of blasting vibration and examines the characteristics of the vibration velocity in the tunnel’s surrounding rock. A load-time history diagram is used to establish a three-dimensional numerical model of the tunnel to analyze the distribution characteristics of the vibration velocity. The applicability of the model is verified by field monitoring data. The simulation revealed a maximum vertical vibration velocity of 48.6 cm/s near the blast source. The response of the rock mass to the blasting load is analyzed at each key position, and the particle vibration velocity law is studied. On this basis, the corresponding Sadovsky formula is thus derived, which can be used to determine the site coefficient, K, and the attenuation exponent, α (with values ranging from 1.268 at the arch waist to 1.594 at the vault and invert), and to predict the vibration velocity in the far blasting area. The maximum charge dose and safety distance are derived under different control standards based on these data. For a control standard of 15 cm/s and a maximum charge of 20 kg, the required safety distance was determined to be 11.8 m. The findings can contribute to blasting scheme design and enhance the security management of construction sites.