The influence of the number of free surfaces on the energy distribution and attenuation law of blasting vibration signals from peripheral holes: field experiment and simulation

Tunnels are commonly excavated using drilling and blasting methods, the surrounding rock is greatly affected by vibration of hole blasting. To study influence number free surfaces on energy distribution attenuation law signals, on-site experiments numerical simulation were conducted. The research results indicate that higher surfaces, smaller peak velocity. longitudinal Fourier main frequency decreases with distance from monitoring point. more surface, greater centroid zero crossing frequency. In addition, shows degree fragmentation after increases increase surface rock.