ABSTRACT
In an excavating project of highway twin tunnels which were separated by a space of 13.5 meters, the blasting vibration field in the existing tunnel was studied. The vibration was induced by the adjacent tunnel blasting. The numerical simulation of the vibration field was conducted. The Peak Particle Velocity (PPV) and the acceleration of blasting vibration were measured in the existing tunnel. The results of simulation and measurement showed that the maximum vibration level appeared at the wall and the arch fronting towards explosion source and that the minimum level was at the other side wall. Based on the data of site tests, the relation between the PPV and the initiation sequence used in cut blast holes was discussed and the PPV attenuation rules were proposed, which were used as a reference material for guiding the tunnel blasting. During the construction, the PPV of blasting vibration caused by adjacent tunneling blasting was monitored in the existing tunnel and was not permitted to exceed 6cm/s. Practice showed that these measures were successful in ensuring safety of the existing tunnel.
