桥墩立井开挖控制爆破研究

桥墩立井开挖爆破,由于其工作断面小,岩石的夹制性大,因此炮孔利用率低,爆破效果差。针对这种情况,在某跨江公路桥桥墩立井的爆破开挖中,根据多次试验的结果,设计了较合理的爆破参数、装药结构及起爆方式,从而改善了爆破效果,提高了炮孔利用率。文中讨论了爆破震动对新浇混凝土的影响机理,在此基础上,设计了间隔装药的周边减震孔,并采用单孔微差起爆,较好地避免了爆破震动对相邻桥墩新浇混凝土的影响。

STUDY ON CONTROLLED BLASTING FOR EXCAVATION OF PIER SHAFT

The excavation blasting o f pier shaft is difficult in getti ng a high utilization factor of bo rehole and good blasting result be cause of a confined working space and clamping property of rock Ther efore,the reasonably designed blas ting parameters,charging structure and initiating mode based on the re sults of many experiments are used for excavation of pier shaft of a certain bridge,thus improving the utilization factor of borehole and blasting result The mechanism abou t the effect of blasting vibration on fresh concrete is discussed in this paper According to the mechan ism,the vibration reduction contou r holes with decked charges are de signed and one hole delay blasting technique is used,which protects t he fresh concrete in near pier sha fts