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Jinan, China

Fu H.,Beijing Jiaotong University | Shen Z.,China Railway 10th Co. | Wang S.,Chengdu Electric Power Bureau | Tang Y.,China Railway 10th Co. | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Digital detonator's delay time is arbitrarily set up according to field requirement and its delay time is very accurate. Digital detonator is one of the most advanced detonators, and is leading the revolution of blasting technology. Several experiments of building tunnels with digital detonator blasting are tried out in Renhechang tunnel of Lanzhou-Chongqing railway, decreasing blasting vibration mechanism with digital detonator is studied. The optimal delay time of blast hole of tunnel is gained; technology of tunnel digital detonator blasting one by one hole is put forward, the blasting vibration is decreased at least 80% in the same blasting advance with detonator blasting with shock-conducting tube, and at least 50% at increasing 25% of blasting advance. Several mixed networks of digital detonator and detonator with shock-conducting tube are tried in order to reduce the blasting cost of tunnel. The optimal joint technology is put forward, the blasting vibration is decreased at least 40% at increasing 25% of blasting advance. The interval between blasting hole delay time greatly affect the result of tunnel blasting, the longer interval between blasting hole delay time result in shorter blasting advance of tunnel and bad fragment, the shorter interval result does not decrease blasting vibration, sometimes increases blasting vibration. The experimental results settle the problem of blasting building railway tunnel in complicated environment, and are also applied to city highway tunnels, the social and economic benefits are acquired. The study result can provide references for tunnel in complicated environment. Source

Fu H.,Beijing Jiaotong University | Fu H.,Nanyang Technological University | Wong L.N.Y.,Nanyang Technological University | Shen Z.,China Railway 10th Co. | And 2 more authors.
Rock Mechanics and Rock Engineering | Year: 2014

The article presents comparison of excavation damage zones resulting from blasting with nonel detonators and blasting with electronic detonators. The nonel detonator is a common type of detonator used in drill-and-blast tunnel excavations, while the use of electronic detonators in recent years has also been gaining popularity in complex tunneling conditions. The tunnel has an overburden of 25 to 40 m. The field study involves an ultrasonic wave measurement in drill holes at two different tunnel sections separately excavated by using electronic detonators and nonel detonators. The results demonstrate that using electronic detonators can help limit the EDZ development in drill-and-blast tunnel excavations. The disturbed zone is dominated by a change of stress and hydraulic head state. The changes in rock mass properties are insignificant or reversible. The presence of the failed zone and damaged zone affects the short-term and long-term stability of the tunnel. Source

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