BLASTING, Volume. 39, Issue 1, 115(2022)
Controlled Blasting of Ground Diaphragm Wall Under Metro Station in Super Large City
The sub-way station in operation is extremely sensitive to blasting vibration.Existing regulations usually stipulate that blasting can only be carried out outside 50 m.The project requires accurate blasting decomposition of the concrete diaphragm wall in the area where the shield machine crosses only 2.8 m below the operating subway station.All blasting work should be completed within 5 hours when the subway stops running.Meanwhile,the normal use of operation,electrical and signal equipment and other equipment in the subway station should be ensured.The deviation of 28 m vertical deep hole is controlled within 5 through the bidirectional control of total station and level on the ground.Precise millisecond time delay blasting with 30 ms is used to form a presplitting fracture zone at the top.Layered charging millisecond time delay blasting is adopted and 72 blasting points are evenly arranged in the 50 m2 crossing area.The results of shield machine excavation after blasting show that the crushing particle size is less than 15 cm,and the station platform with the same structure as the blasting object is 3.4 cm/s on blasting vibration velocity at the station platform 5.6 m away from the explosion point,which achieves the dual purpose of ensuring the safety of the operating station and the crossing effect of the shield machine,and the subway station structure and electrical facilities operate safely after blasting.
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LIU Wen-guang. Controlled Blasting of Ground Diaphragm Wall Under Metro Station in Super Large City[J]. BLASTING, 2022, 39(1): 115
Received: Sep. 24, 2021
Accepted: --
Published Online: Jan. 24, 2024
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