Abstract:

The utilization rate of blasting holes is usually influenced by asymmetry of cutting holes, irrational layout of cut zone, large spacing among cut holes, large spacing among assistant holes and nonstemming of the blasting holes. In order to improve the utilization rate of blasting holes and minimize the blasting vibration velocity, some factors are analyzed based on the blasting excavation of Zone 1 of top heading of Metro station on No. 2 Line in Qingdao. In this paper, the parameters of wedgeshaped cut are optimized by means of theoretical calculation and construction experience. In addition, multiple free surface is taken into consideration to check the maximum individual ignition explosive quantity. The results show that the utilization rate of blasting holes was improved to 90.5%, and the blasting vibration velocity was limited within 0.7 cm/s by the compound wedgeshaped cut used.

Key words: Qingdao Metro, tunnel, wedgeshaped cut, blasting vibration, utilization rate of blasting hole, blasting parameter