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Experimental Study of the Vibration Absorption Mechanism of Staged Wedge-Cut Blasting Technology
(1 Zunyi New Area Investment Co. Ltd., Zunyi 563000; 2 School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031;3 China Railway East International Group, Kuala Lumpur 58100)
Abstract In order to solve the contradiction between blast-induced vibration absorption and construction efficien? cy of tunnels approaching existing buildings by the drill and blast method, an optimized vibration absorption blasting technique named staged wedge-cut millisecond delayed blasting technology is developed, which is appropriate for tunnels in medium or soft rock masses. Specifically, it makes use of segmented alternative charging structures and millisecond delayed blasting technology to guarantee the formation of a cut cavity in a hierarchical way from the outside in and achieves the goals of effective vibration absorption and a good advance rate. Based on a detailed analysis of the mechanism of rock breaking and vibration absorption during staged cut blasting and theories of millisecond blasting and stress wave propagation, the determination method for the key parameters affecting vibration ab? sorption and cut effect is proposed (such as the cut depth ratio, the distribution ratio of segmented charging, the dip angle of the cut hole and the delayed time for each segment) and applied to the parameter design for the tunnel blasting test at the site. The site blasting test indicates the new staged wedge-cut blasting technique can effectively reduce the blasting-induced vibration by more than 30%, guarantee construction speed, and obtain a good advance rate and effect compared with the conventional cut blasting method.
Abstract：
In order to solve the contradiction between blast-induced vibration absorption and construction efficien? cy of tunnels approaching existing buildings by the drill and blast method, an optimized vibration absorption blasting technique named staged wedge-cut millisecond delayed blasting technology is developed, which is appropriate for tunnels in medium or soft rock masses. Specifically, it makes use of segmented alternative charging structures and millisecond delayed blasting technology to guarantee the formation of a cut cavity in a hierarchical way from the outside in and achieves the goals of effective vibration absorption and a good advance rate. Based on a detailed analysis of the mechanism of rock breaking and vibration absorption during staged cut blasting and theories of millisecond blasting and stress wave propagation, the determination method for the key parameters affecting vibration ab? sorption and cut effect is proposed (such as the cut depth ratio, the distribution ratio of segmented charging, the dip angle of the cut hole and the delayed time for each segment) and applied to the parameter design for the tunnel blasting test at the site. The site blasting test indicates the new staged wedge-cut blasting technique can effectively reduce the blasting-induced vibration by more than 30%, guarantee construction speed, and obtain a good advance rate and effect compared with the conventional cut blasting method.
.Experimental Study of the Vibration Absorption Mechanism of Staged Wedge-Cut Blasting Technology[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(4): 186-192
2017, Vol. 54 