This paper gives an analysis of blasting vibration influence of a traversing diversion tunnel construction on the above existing railway tunnel

by using numerical methods and field test

associated with the practical situation of Shoupayan Tunnel of Nei-Kun Railway which was traversed by the diversion tunnel of Baishuijiang Cascade Ⅲ Hydropower Station in Yanjin Yunnan Province. The analysis result indicates that

empirical formula’s results are safe and feasible. Numerical simulation results are more contiguous with engineering practice than those of empirical formula. When the distance between diversion tunnel face and railway tunnel is less than 4D (D is the hydraulic tunnel diameter)

the vibration speeds at the point of intersection in railway tunnel must be monitored

especially for the vertical vibration speed. When constructing the diversion tunnel under the railway tunnel

the detonator of the maximum segment should be less than 2.5kg in order to satisfy control criterion of vibration speed. The blasting vibration monitoring in the course of excavation and the blasting parameters modification timely according to monitoring results are the guarantees for the successfully nearby excavation.