Rock excavation by blasting l Introduction Proper rock fragmentation(破碎) is the key first element of the rock mass excavation, which consists of four steps of drilling, blasting, loading (装碴)and hauling(运输). The physical operations of drilling, loading and hauling are very heavily machine-oriented whereas blasting is engineering/design/experience oriented. Today a number of mining(采矿) and quarrying(采石场) operations in recognizing this truism(真实性) ‘farm-out’ their blast engineering/design/implementation(实施) to a blasting contractor with the required specialized expertise. The in-house expertise is focused on the three remaining unit operations of drilling, loading and hauling which actually service the fourth, blasting. Important in the past and important today, carefully engineered blasting will be an even more important aspect of successful construction of large dam. The operation referred to as blasting is performed to loosen rock in order that it may be excavated or removed from its existing position. Blasting is accomplished by discharging(引爆-initiating) an explosive that has been placed in a hole specially provided for this purpose. The energy associated with an explosive is the result of the pressure produced in the gases that are formed by the explosive. There are many types of explosives and method of using them. A full treatment of each explosive and method is too comprehensive for inclusion in this book. For more complete discussions of the subject the reader is referred to handbooks on blasting, published by manufacturers of explosives. www.m448中国最庞大的资料库下载