松动爆破在陡边坡厚层堆积体开挖中的应用

Application of Loosening Blasting in Excavation of Thick Deposit of Steep Slope

滇中引水工程蔡家村隧洞出口边坡开挖高度约38 m,开挖坡比为1∶0.3,崩塌堆积体厚度达8 m,开挖支护难度极高。基于山体爆破工程实例,分析了孔内延迟和孔内外联合延迟爆破技术的优缺点,研究了陡边坡、厚层堆积体开挖中低单响、低单耗的微差爆破网路,提出了加长和分段堵塞、修正预裂孔线装药密度、预留岩埂等方法,形成了孔内炸药药量控制、装药结构升级、起爆网路优化、外部防护为一体的陡边坡“内-外”联合延迟松动爆破技术。通过采取一系列的爆破控制措施,滇中引水工程陡边坡厚层堆积体条件的松动爆破效果较好,有效控制了爆破振动、飞石、粉尘等,可为类似工程提供一些参考经验。

The slope at the exit of Caijiacun tunnel of Central Yunnan Water Diversion Project is highly difficult to be supported with an excavation height about 38 m,excavation slope ratio of 1∶0.3,and a thickness of collapse deposit reaching 8 m.Having analyzed the merits and shortcomings of inter-hole delay and inter-row delay,we researched the millisecond blasting network with low single sound and low unit consumption in excavating the thick deposit of steep slope.We proposed a loosening blasting technology integrating inter-hole and inter-row delay blasting.The technology integrates the control of explosive charge in hole,the upgrading of charge structure,the optimization of initiation network and external protection.Methods of lengthening and sectional plugging,correcting the charge density of pre-splitting hole line,and reserving rock ridges are put forward.The proposed technology is demonstrated to be of sound loosening blasting effect for the thick deposit of steep slope of Central Yunnan Water Diversion Project with the blasting vibration,flying rock and dust been effectively controlled.