Safety control of blasting vibration in new tunnel excavation adjacent to existing tunnel
摘要
The blasting excavation of the new tunnel will adversely affect the adjacent existing tunnel structure, to ensure the safe operation of the busy existing tunnel, the study of blasting vibration safety control is critical. In this study, based on the Xiamen New Damaoshan Tunnel No.1 project, the conversion relationship between the input energy of blasting vibration and the elastic strain energy and kinetic energy of concrete mass unit is analyzed according to the principle of conservation of energy. The estimation method of " twice the peak kinetic energy of the peak vibration velocity instead of the maximum elastic strain energy" is proposed, and verified by numerical simulation method. On this basis, the safe control of the vibration velocity of the existing tunnel in this project was derived by combining it with the energy criterion of concrete damage. Secondly, the blasting vibration damping control test is carried out using a test well and on-site monitoring, and the relationship between the blasting distance and the peak vibration velocity and damping efficiency is obtained for the three control techniques of the Single hole blasting, Preset damping holes, and Rope saw cutting, and the results show that the damping effect of the control technique of the Rope saw cutting is the best, and the damping effect of the Preset damping holes is second to the control technique of the damping. Finally, according to the adaptive range of different vibration control techniques for engineering application, through the peak vibration velocity monitoring of the existing tunnel, the peak vibration velocity is less than the safe vibration velocity control value proposed in this study and is in a safe state.