Abstract:

The running tunnel from Zhenxinlu Station to Xuzhoudong Railway Station of Line 1 of Xuzhou Rail Transit System is constructed by cutandcover method. The running tunnel is located in complicated geological and surrounding environment, therefore controlled blasting is carried out to minimize the impact of the vibration and flying stones on the adjacent buildings. Vibration zone is arranged, which reduces the vibration velocity by 35%; the maximum charging quantity of single blow in the main blasting zone is strictly controlled and the blast hole parameters and the charging parameters are properly determined, which ensures more than 90% blast hole utilization ratio; presplitting blasting technology is adopted for the slopes, which ensures 85% blast hole trace ratio and less than 15 cm overbreak; effective stemming and covering measures are taken, which brings the flying stones under effective control; comprehensive warning and protection measures are taken, which minimizes the safety risks on the surrounding environment. In the end, 200 000 m3 rocks have been excavated within 6 months, and satisfactory construction progress, safety and cost efficiency have been achieved. The practice shows that the technologies adopted are rational and effective. 

Key words: rail transit, cutandcover tunnel, complex environment, controlled blasting, building safety