Abstract:

The mined small clear spacing twintube tunnel on Shixinlu StationShiqiaopu Station on Line No. 5 of Chongqing railway transit crosses many buildings. The influence of blasting vibration on environment is studied; and a series of technologies, such as energy conservation and environmental protection hydraulic blasting, step by step construction, millisecond controlled blasting, blasting parameter optimization, vibration reduction hole increasing and enlarging and informationization monitoring, are adopted. The blasting vibration velocity has been brought under effective control by optimizing drilling and blasting parameters. Some conclusions are drawn as follows: 1) The blasting vibration velocity at the cut eye is the largest; the vibration velocity along longitudinal direction is the largest, followed by that along radial direction, and that along tangent direction is the smallest; and the blasting vibration velocity before tunnel crosses underneath building is smaller than that after tunnel crosses underneath buildings. 2) Compared to traditional blasting, the blasting vibration velocity induced by hydraulic blasting can be reduced by 13%-22%; compared to hydraulic blasting, the blasting vibration velocity induced by increasing vibration reduction hold method can be reduced by 16%-28%.

Key words: small clear spacing tunnel, undercrossing building, vibration reduction hole, hydraulic blasting, millisecond controlled blasting, vibration velocity contro