Based on the engineering background of the Miaoya forked tunnel

the study of vibration characteristic of the ground at the large-span shallow part and blasting vibration reduction technology for large-span excavation has been done

according to the regression analysis for the results of monitoring on blasting vibration

the mathematical model for vertical propagation of blasting vibration has been established. Some conclusions are obtained by analyzing the vibration characteristic of the ground and the tunnel

the dominating vibration frequency at surface mass point mostly focuses on low frequency

the decreasing tendency of dominating vibration frequency at surface mass point is not obvious when distance increases

because some blasting earthquake waves are absorbed by the earth surface covered with soil of certain thickness; the high frequency is mostly absorbed by the concrete of the tunnel lining

so the blasting vibration impacting on the rock becomes weaker

the ground blasting vibration velocity of the excavation region is higher than that of the rock region; the ground blasting vibration velocity at the top of excavation region should be less than that of blasting security control in the large-span shallow tunnel.