Lecture 8- Rock Blasting

Lecture 8- Rock Blasting - C E M 6 2 C o n s t r u c t i o...

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Unformatted text preview: C E M 6 2 C o n s t r u c t i o n M e t h o d s CEM 602 Construction Methods Lecture 8- Rock Blasting 1 L e c t u r e 7- R o c k E x c a v a t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Blasting Rock 2 L e c t u r e 7- R o c k E x c a v a t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Blasting Drilling and blasting is the most frequently used rock excavation technique Performed to break rock to be quarried or to excavated Accomplished by discharging an explosive Explosive can be placed in unconfined or confined manner Two forms of energy are released in detonation; shock and gas 3 L e c t u r e 7- R o c k E x c a v a t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Blasting Unconfined charge works by shock energy Confined charge has a high gas energy output Gunpowder was developed in China in the thirteenth century. First recorded use of an explosive for mining was in 1627 at the Royal Mines of Schemnils at Ober-Biberstollen, Hungary Blasting with black powder was banished by nitroglycerin L e c t u r e 7- R o c k E x c a v a t i o n 4 C E M 6 2 C o n s t r u c t i o n M e t h o d s Glossary of Terms Bench: Horizontal ledge of an excavation face along which holes are drilled for blasting Benching: Process of excavating using ledges in a stepped pattern Bench height: Vertical distance between the base of an excavation and the ledge above where the blastholes are drilled Blasthole: A hole drilled (borehole) into rock to enable the placing of an explosive 5 L e c t u r e 7- R o c k E x c a v a t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Glossary of Terms Blasting (shot): The detonation of an explosive to fracture the rock Blasting agent: The classification of a particular type of explosive compound from the standpoint of storage and transportation Burden: The distance from the explosive charge to the nearest free or open rock face Deflagration: A rapid chemical reaction in which the output of heat is enough to enable the reaction to proceed and be accelerated without input of heat from another source. 6 L e c t u r e 7- R o c k E x c a v a t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Glossary of Terms Density: An explosive's density is its specific weight, usually expressed as grams per cubic centimeter (g/cc) Heave: The displacement of rock as a result of the expansion of gases from firing an explosive Lead wires: The wires that conduct the electric current from its source to the leg wires of the electric detonator Leg wires: The wires that conduct the electric current from lead wires to an electric L e c t u r e 7- R o c k E x c a v a t i o n 7 C E M 6 2 C o n s t r u c t i o n M e t h o d s Glossary of Terms MS delay detonator (millisecond): A detonator that has a built-in delay element commonly available in 25/1000 sec increments Nitroglycerin. A powerful explosive liquid obtained by treating glycerol with a mixture...
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Lecture 8- Rock Blasting - C E M 6 2 C o n s t r u c t i o...

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