采礦工程畢業(yè)設計翻譯---爆破在井巷掘進中的應用

1、附錄 附錄 外文翻譯 外文翻譯APPLICATION OF BLASTING IN DRIVING TUNNEL1 FRAGMENTATIONFragmentation is the breaking of coal, ore,or rock by blasting so that the bulk of the material is small enough to load, handle and transport.Fragmen

2、tation would be at its best when the debris is not smaller than necessary for handling and not so large as to require hand breaking or secondary blasting .Energy must be supplied to rock by direct or indirect means to fr

3、agment that rock and the type of loading system.Fragmentation energy is consumed by the main mechanisms: (1) creation of new surface area (fracture energy), (2)friction (plasticity) and (3)elastic wave enegy dispersion.T

4、he loading method determines the relative proportions and the amount of energy consumed in fragmenting a given rock type. Unonfined tensile failure consumes the least energy with an increasing a,mount of energy required

5、as the rock is more highly confined within a compressive stress field during fragmentation The way energy is applied by tools to cause rock or mineral fragmentation is important in determining fragmentation efficiency. T

6、o best design fragmentation tools and optimize fragmentation systems it would be desirable to know how rock properties influence breakage.The strength of rock is influenced by the environmental conditions imposed on the

7、rock.Those of most importance in rock are (1)confining pressure ,(2)pore fluid pressure, (3)temperature and (4)rate of load application .Increase in confining pressure, as with increasing depth beneath th earth's sur

8、face or under the action of a fragmentation tool, causes an increase in rock strength .Apparent rock strength decreases as porc fluid pressure increases, since it decreases the effect of confining pressure. Although chem

9、ical effects of pore fluids influence rock strength, they generally are small compared to the confining pressure effect, except for a small minority of rock types .Increase in rock temperature causes a decrease in rock s

10、trength.This effect is very small because of the small ambient temperature changes Compressed air chargers have been in use is Sweden for about 20 years. The first type consisted of aluminum pipes connected together and

11、the cartridges were blown into the hole with an air pressure of 42 pounds per square inch .since that time the charging tube has been replaced by anti-static treated plastic hose of a special design. A charger includes a

12、 foot-operated valve, reduction vavle with air hose, breech, connecting tube and charging hose.The semi-automatic charger permits the continuous insertion of explosive cartridge at the same rate as they are charged in th

13、e hole by the hose .Instead of a valve being used ,the cartridges pass through an air lock between two flaps. The air pressure in the charging hose is retained while cartridges are pressure in the charging hose is retai

14、ned while cartridges are beins inserted .The semi-automatic charger permits considerably higher charging capacity than the normal type of charger.Explosives in the form of the form of loose material, usually ammonium nit

15、rate explosives(ANFO), require special chargers. Two types can be differentiated: pressrure vessel machines and ejector units. Pressure vessel machines are particularly suitable for crystalline An explosives with good ch

16、arging capacity. Ejector units are operate by an ejector sucking up explosive from a container through a charging hose. The explosive is then blown through the charging hose into the drill hole .There are, also combined

17、pressure ejector machines. The charging hose used for ANFO charging operations must conduct electricity and have a resistance of at least 1K?/m and max.30K?/M.Nitro Nobel has developed a special pumping procedure which c

18、onsists of a tanker vehicle which is used to pump explosive directly the drill holes. The charging capacity is very high in the case of large diameter drill holes.3 CONTROLLED BLASTING TECHNIQUTES Controlled blasting is

19、used to reduce overbreak and minimize fracturing of the rock at the boundary of an excavation. The four basic controlled blasting techniques are: line drilling, presplitting, cushion blasting and smooth blasting.Line dri