Vibration response and evaluation system of cross-tunnel blasting

Based on the Cao Mao mountain cross-tunnel project, on-site monitoring and theoretical study of the blasting vibration effect of the cross-tunnel were carried out, and the dynamic response of the existing tunnel under instantaneous explosion loads was analyzed. The equivalent radius of action (re) was introduced to replace the maximum charge per delay (Q) to improve the traditional prediction equations for the peak particle velocity (PPV) and the main frequency (fc). When the intersection is used as the boundary, the attenuation of the PPV and fc can be studied separately. The results show that the effect of blasting vibrations in front of and behind the face is affected by the free surface. The blasting vibration alarm value, the early warning value, and the natural frequency of the existing tunnel are regarded as safety control limits. The controlled blasting distance of the cross tunnel can be obtained by regression calculation. In addition, the mathematical relationship between the PPV and fc is used to quantitatively consider the influence of the frequency on the blasting safety vibration threshold, compensating for the lack of consideration of the influence of the frequency in various national blasting safety regulations or standards.