Based on the background of ultra-small spacing tunnels of Nanjing Metro and combined with the existing research results as well as domestic and international codes

a method of blasting technology using in small spacing later tunnel is studied in order to keep the security and stability of the antecedent line. Using modern information technology theory as the basis and making full use of on-site monitoring

the vibration velocity of particle in antecedent tunnel can be monitored and analyzed for vibration reduction and vibration isolation during the blasting. The final results show that the blasting design parameters such as optimized footage driving cycle

the maximum loading dose and the time difference of sectional blasting are reasonable during the construction. The blasting design did not affect the safety of the antecedent tunnel. While through the three dimensional numerical simulation

after observing the variation of particle vibration in antecedent line over time

we find that the maximum vibration velocity meets the relevant codes; and the optimized blasting design is reasonable. Through numerical analysis

we find that the tangential and centripetal vibration velocity in tunnel side wall are much faster than the vibration velocity in arch springing

the effect in antecedent blasting surface is slight greater than the rear lining; and the surface vibration of lining in left tunnel which near blasting point is greater than the surface in blasting point. The research results to the construction of this protect provide a scientific basis and technical guidance for similar future tunnel blasting excavation engineering and construction methods in theory.