Surface Drilling And Blasting Pdf
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- Drilling and blasting
- Faqs On Mining And Blasting Pdf
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- Drilling and blasting
Drilling and blasting is the controlled use of explosives and other methods such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining , quarrying and civil engineering such as dam , tunnel or road construction. The result of rock blasting is often known as a rock cut.
Drilling and blasting
Drilling and blasting is the controlled use of explosives and other methods such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining , quarrying and civil engineering such as dam , tunnel or road construction. The result of rock blasting is often known as a rock cut. Drilling and blasting currently utilizes many different varieties of explosives with different compositions and performance properties. Higher velocity explosives are used for relatively hard rock in order to shatter and break the rock, while low velocity explosives are used in soft rocks to generate more gas pressure and a greater heaving effect.
For instance, an early 20th-century blasting manual compared the effects of black powder to that of a wedge, and dynamite to that of a hammer. Before the advent of tunnel boring machines TBMs , drilling and blasting was the only economical way of excavating long tunnels through hard rock, where digging is not possible. The decision whether to construct a tunnel using a TBM or using a drill and blast method includes a number of factors.
Tunnel length is a key issue that needs to be addressed because large TBMs for a rock tunnel have a high capital cost, but because they are usually quicker than a drill and blast tunnel the price per metre of tunnel is lower. Managing ground conditions can also have a significant effect on the choice with different methods suited to different hazards in the ground. The innovation spread quickly throughout Europe and the Americas.
The standard method for blasting rocks was to drill a hole to a considerable depth and deposit a charge of gunpowder at the further end of the hole and then fill the remainder of the hole with clay or some other soft mineral substance, well rammed, to make it as tight as possible. A wire laid in the hole during this process was then removed and replaced with a train of gunpowder. This train was ignited by a slow match , often consisting simply of brown paper smeared with grease, intended to burn long enough to allow the person who fires it enough time to reach a place of safety.
The uncertainty of this method led to many accidents and various measures were introduced to improve safety for those involved. One was replacing the iron wire, by which the passage for the gunpowder is formed, with one of copper.
Another was the use of a safety fuse. This consisted of small train of gunpowder inserted in a water-proof cord, which burns at a steady and uniform rate. This in turn was later replaced by a long piece of wire that was used to deliver an electric charge to ignite the explosive.
The first to use this method for underwater blasting was Charles Pasley who employed it in to break up the wreck of the British warship HMS Royal George which had become a shipping hazard at Spithead. An early major use of blasting to remove rock occurred in when the British civil engineer William Cubitt used 18, lbs of gunpowder to remove a foot-high chalk cliff near Dover as part of the construction of the South Eastern Railway.
While drilling and blasting saw limited use in pre-industrial times using gunpowder such as with the Blue Ridge Tunnel in the United States, built in the s , it was not until more powerful and safer explosives , such as dynamite patented , as well as powered drills were developed, that its potential was fully realised.
In , 2. In this year the Soviet Union was the leader in total volume with 2. The positions and depths of the holes and the amount of explosive each hole receives are determined by a carefully constructed pattern, which, together with the correct timing of the individual explosions, will guarantee that the tunnel will have an approximately circular cross-section.
During operation, blasting mats may be used to contain the blast, suppress dust and noise, for fly rock prevention and sometimes to direct the blast. As a tunnel or excavation progresses the roof and side walls need to be supported to stop the rock falling into the excavation. The philosophy and methods for rock support vary widely but typical rock support systems can include:. Typically a rock support system would include a number of these support methods, each intended to undertake a specific role in the rock support such as the combination of rock bolting and shotcrete.
Blast-hole drilling at the Bingham Canyon Mine , Utah. Note the pattern of drill holes being prepared for blasting. Sideling Hill road cut formed by rock blasting. Map describing the clearance zones during blasting in a limestone quarry. These notices are produced by surveyors see topography. Blast hole drilling in a dolerite quarry at Prospect Hill , Sydney , Australia.
From Wikipedia, the free encyclopedia. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Loading blast holes with ANFO. Rock surface newly blasted.
This is called pre-split, it's a technique to leave a smooth face. The Shot-Firer's Guide. Tunelling and tunnel mechanics: a rational approach to tunnelling. This article incorporates text from this source, which is in the public domain. Rock Blasting and Explosives Engineering. CRC Press. CBC News. Retrieved 26 September Categories : Tunnel construction Mining Explosives Civil engineering.
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Faqs On Mining And Blasting Pdf
Explosives Energy Release and Rock Breakage: Mechanism of rock breakage while release of Explosives energy upon detonation and other relevant points are discussed below:. Velocity of detonation VOD of explosive is function of Heat of reaction of an explosive, density and confinement. The detonation of explosives in cylindrical columns and in unconfined conditions leads to lateral expansion between the shock and C-J planes resulting in a shorter reaction zone and loss of energy. Thus, it is common to encounter a much lower VOD in unconfined situations than in confined ones. Rock breakage by Detonation and Interaction of explosive energy with rock — There are three sources of generation of fragments in mines: a Fragments formed by new fractures created by detonating explosive charge, b In-situ blocks that have simply been liberated from the rock mass without further breakage and c Fragments formed by extending the in-situ fractures in combination with new fractures. Rock fragmentation by blasting is achieved by dynamic loading introduced into the rock mass.
Holmberg, Roger. This paper gives a short description of two computer programs. The first program is for tunneling design and the second one is for bench blasting calculations. The availability of options like using a parallel cut or different types of angled cuts makes the tunnel program vary suitable for various sizes of tunnel areas. It is also possible to include smooth blasting instead of a normal contour blasting method. The bench blasting program makes it possible to compute the drilling patterns adapted to the used drilling diameter used for normal spacing-burden ratio or with respect to the wide space blasting method. DieseSchrift gibt eine kurze Beschreibung zwei Kbmputer-Programme.
The examination shall include questions related to the license classification requested. Which cut is used for solid blasting in Indian coal Mines Wedge cutfaqs on mining and blasting - greenmountainpta. Check price. Geologist explore the economic mineral deposits for mining. A lot of methods are adopted to exploit the valuable economic mineral resources through open,faqs on mining and blasting pdf - bregroup,drilling amp blasting in iron ore mine -. Aug 11, drilling and blasting for iron ore Search mining process drilling blasting iron ore to. Get Price.
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Drilling and blasting
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Blast-Design Overview. Blast parameters: • Burden. • Spacing. • Bench height. • Powder column: • Hole diameter. • Hole depth. • Powder factor. • Subdrilling.
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