Abstract: In the light of the small distance between the new roadway and the existing roadway， the seismic wave generated by blasting operation will affect the safety and stability of the initial shotcrete structure of the existing roadway.Thus，taking a mine project as the background， the spatial intersection roadway model is established，and the numerical method is used to imitate the influence of the blasting excavation of new ventilation roadway on existing roadway.The paper analyzes the dynamic effects of the blasting excavation of new ventilation roadway with different spacing and different surrounding rock grade on shotcrete in existing traffic roadway.Combining with the relevant engineering specifications，the blasting safety spacing is optimized and then the results are compared by field measurement.The comparison results show that the blasting excavation of new ventilation roadway at lower part has the greatest influence on arch bottom and arch foot of upper traffic roadway， and should be monitored on the key point.The vertical spacing of roadway is less than 1.5D，the vibration velocity of shotcrete structure varies greatly with the increase of spacing， and otherwise it is more than 1.5D.The change is not obvious， and the optimal blast spacing should not be less than 2.5D.The study results can provide reference for the design and construction of the site and similar roadway engineering with small clear distance.

Key words: Underground mining, Shotcrete structure, Spatial intersection roadway, Blasting excavation, Dynamic effect, Safety spacing