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1、1 統(tǒng)的類型。破巖的能量在以下三個主要機理內被消耗掉:(1)形成新的表面(破巖能量),(2)的強度增加。隨著孔隙流體壓力增加,巖石的視強度就降低 因為它減弱了約束力的作用。雖2眼裝藥方裝率,同時又改進裝藥密度,因眼的利用率較高。近幾年來采用了半自動裝藥器,主要用于井1 統(tǒng)的類型。破巖的能量在以下三個主要機理內被消耗掉:(1)形成新的表面(破巖能量),(2)的強度增加。隨著孔隙流體壓力增加,巖石的視強度就降低 因為它減弱了約束力的作用。雖2眼裝藥方裝率,同時又改進裝藥密度,因眼的利用率較高。近幾年來采用了半自動裝藥器,主要用于井壓風裝藥器在瑞典已使用了大約二十年。第一種裝藥器由幾節(jié)鋁管連接而成并
2、用 42 磅英寸 的壓風把藥卷吹入 而是讓藥卷通過一個位于兩之間的氣室。裝藥時裝藥欽管中的風壓不變。半自動裝藥器的吹3控 眼直徑,不裝藥。靠近輪廓線鉆眼眼,起裝藥量及眼距均比其眼小。輪廓線眼的最大24壓風裝藥器在瑞典已使用了大約二十年。第一種裝藥器由幾節(jié)鋁管連接而成并用 42 磅英寸 的壓風把藥卷吹入 而是讓藥卷通過一個位于兩之間的氣室。裝藥時裝藥欽管中的風壓不變。半自動裝藥器的吹3控 眼直徑,不裝藥??拷喞€鉆眼眼,起裝藥量及眼距均比其眼小。輪廓線眼的最大24寸眼距為 眼直徑的 6-12 2-3英尺處不裝藥,但要充填 泥。預裂爆50 英尺。預裂 眼比鄰近主 眼先起爆,以形成有利于主 中在鄰
3、近主 2-6。法采用大直眼法相似。因為鉆大直眼容易準直,所以緩眼口外,藥卷不用充填 泥;光爆 。4巖鉆 眼、裝和。(3) 安裝支架,支護剛掘出的巷道,敷設接長軌道、風管和電纜,為下個循環(huán)作好準備工作的其他 。式。在較大斷面巷道中,斜角眼掏槽比直眼掏槽優(yōu)越,因為 槽垂直或水平楔形掏槽。對于深度較大眼或難大直徑掏槽直眼在大斷面巷道中可為良好的擴槽創(chuàng)造條件。采用直眼掏槽, 眼組的深度可比斜眼掏槽大一些,因為每茬 的進度增加了,證明其更為經濟。直眼掏槽的槽眼要平行,眼距要適當,其深度要比其他 1/2 光爆 。4巖鉆 眼、裝和。(3) 安裝支架,支護剛掘出的巷道,敷設接長軌道、風管和電纜,為下個循環(huán)作好
4、準備工作的其他 。式。在較大斷面巷道中,斜角眼掏槽比直眼掏槽優(yōu)越,因為 槽垂直或水平楔形掏槽。對于深度較大眼或難大直徑掏槽直眼在大斷面巷道中可為良好的擴槽創(chuàng)造條件。采用直眼掏槽, 眼組的深度可比斜眼掏槽大一些,因為每茬 的進度增加了,證明其更為經濟。直眼掏槽的槽眼要平行,眼距要適當,其深度要比其他 1/2 眼布置有無數種。甚至在同一巷道中,隨著巖石性質的變化也要改變 眼組 眼隨前一響眼來說,重要順序。一般來說, 的順序應使每個 面。每茬 APPLICATIONOFBLASTINGINDRIVING1ion is the breaking of coal, ore,or rock by blas
5、ting t the bulk of the material is enough to load, handle and ion would be at its best when APPLICATIONOFBLASTINGINDRIVING1ion is the breaking of coal, ore,or rock by blasting t the bulk of the material is enough to load, handle and ion would be at its best when the debris is not nsaryforhandlingand
6、notsolargeas torequirehandbreakingorsecondaryblastingEnergy must d to rock by direct or indirect means to t rock and the type loading ion energy is consumed by the echanisms: (1) creation of new area(fractureenergy),(2)friction(plasticity)and(3)elasticwaveenegy.The loading method determines the rela
7、tive 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 as the rock is more highly confined within a compressive stress field during fragmen ion The way energy is app d by t
8、ools to cause rock or mineral fragmen ion is important in determining fragmen ion efficiency. To best design fragmen ion tools and optimize fragmen systemsitwouldbe desirabletoknowhow rockpropertiesinfluence The strength of rock is influenced by the environmental conditions ed on the rock.Those most
9、 importance in rock are (1)confining re ,(2)pore fluid re, (3)temperature and (4)rate load application .Increasein confining re,as with increasing depth beneath th rface or the action of a ion tool, causes an increase in rock strength .Apparent rock strength decreases porc fluid re increases, since
10、it decreases the effect of confining re. Although chemical of pore fluids influence rock strength, they generally are small compared to the confining re except for a small minority of rock types .Increase in rock temperature causes a decrease in rock strength.This effect is very small because of the
11、 small ambient temperature changes found during AnincreaseinrateofloadapplicationcausesanapparentincreaseinrockRock exhibits directional t in fluence the way it breaks. These are embodied in concept of rock fabric ,which connotes the structure or configuration of the aggregate components as well as
12、the physical or mechanical property manifes ions. Rock fabric ont only relates to the preferred orien ion of mineral constituents and their planes of weakness, but also to the configuration of discontinuities, microcracks and pores.Jo s and bedding planes have great influence on fragmen ion at field
13、 scale.Physical properties of rock (density,inden ion,hardness,abrasivehardness and porosity frequently used in conjunction with mechanical properties to etter empirical esti mations of 2 BLASTHOLE CHARGING Drill hole charging can be carried out in different ways depending on whether the explosive u
14、sed in cartridges he form of loose material. The oldest charging method s the use of a ing and this system is still used to a very great extent .During the last 20years, compressed air chargers been used and these2 BLASTHOLE CHARGING Drill hole charging can be carried out in different ways depending
15、 on whether the explosive used in cartridges he form of loose material. The oldest charging method s the use of a ing and this system is still used to a very great extent .During the last 20years, compressed air chargers been used and these machines provide both good capacity and also an improved le
16、vel of concentration t the drill holes are utilized to a higher degree. During the last few semi-automaticchargershavebeenouse,primarily inundergroundwork.Compressed airfor he form of loose material have also o use on a large scale. As far as blasting is concerned, l methods have been developed thro
17、ugh which charging capacity thecaseof largediameterdrillholesispractically A ing rod must be made of wood or plastic. It must not be too thick in relation to the drill diameter since this can crush and damage fuse or electric detonator cables during charging work. If a degree of packing is to be obt
18、ained during charging ting rod then only one cartridge should be charged and ed. The detonator must be correctly o the drill hole during Compressed air chargers have been in use is Sweden for about 20 years. type consisted aluminum pipes connected together and the cartridges were o the hole n air re
19、 of pounds per square inch t time the charging tube has been replaced by anti-ic treated hose of a l design. A charger includes a foot-operated valve, reduction vavle ir hose, connectingtubeandcharging The semi-automatic ermits the continuous insertion of explosive cartridge at the same as they are
20、he y the hose .Instead of a valve being used ,the cartridges pass through air lock n two flaps. The air hecharging hose is retained while cartridges are re the charging hose is retained while cartridges are beins inserted .The semi-automatic charger considerablyhigherchargingnthe normaltypeof he for
21、m of the form of loose material, usually ammonium nitrate require l chargers. Two types can be differentiated: pressrure machines and ejector re machinesareparticularly suitableforcrystallineAnexplosiveswithgoodchargingEjector units are operate by an ejector sucking up explosive from a container thr
22、ough a charging hose. explosive is then blown through the charging o the drill hole .There are, also combined ejector machines. The charging hose used for ANFO charging operations must ectricity and aeast1K/mandNitro Nobel has developed a l procedure which consists of vehicle which used to pump expl
23、osive directly the drill holes. The charging capacity is very high in the case of diameterdrill3 CONTROLLED BLASTING Controlled blasting is 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,
24、 presplitting, cushion blasting and smooth blasting.Line drilling, the ear st controlled blasting technique, involves drilling a row of closely spaced holes along the final excavation line, providing a plane of weakness to which to break. Line drill holes, 4 diameters apart and 3 CONTROLLED BLASTING
25、 Controlled blasting is 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 drilling, the ear st controlled blasting technique, involve
26、s drilling a row of closely spaced holes along the final excavation line, providing a plane of weakness to which to break. Line drill holes, 4 diameters apart and contain no explosive. The blastholes adjacent to the line drillholes normally loaded lighter and are on closer n the other blastholes. um
27、 depth for line drilling about 30 ft .Line drilling involves no finalhe final row of holes, and thus minimizes damage to Presplitting, sometimes called preshearing ,involves a single row of boreholes ,usually 2 to 4 in diameter ,drilled along the final excavation at a spacing of 6 to 12 borehole dia
28、meters .Dynamite 1to 1.5 in . in size on 1 to 2 ft .centers usually are string-loadde on detonating cord ,although lsmall-diameter cartridges with l couplers are available for total column loading .In formations ,closer spacings with usually is loaded somewhat der loads are required .The bottom 2 to
29、 3 ft .of n the remainder .Stemming n and around the charges is optional .The top 2 to 3 ft . of borehole is not loaded ,but is stemmed. The t can presplit is limited by hole alignment ,with 50 ft .being um .The presplit holes are fired before the adjacent primary holes to provide a fracture plane t
30、o which the primary blast can break presplitting it is difficult to determine the results until the adjacent primary blast is shot .For reason,presplittingtoofar inadvanceis mended.Presplittingseldomisdone Cushion blasting involves drilling a row of 2 to 6-in .diameter boreholes along the final line
31、 ,loading light well-distributed charge y stemmed and firing after the main is removed n before ,as in presplitting. The burden on the holes is slightly n spacing .Wedges may be used to abut the charges to the excavation side of the borehole and damage to thefinal wall .Eeplosiveloadingissimilar t i
32、npresplitting .Cushionblasting has been to depths near 100 ft .in a single lift with the larger-diameter boreholes because alignment is more retained.CushionblastingseldomisdoneSmooth blasting is the underground art of cushion blasting .At the perimeter of the tunnel drift ,closely spaced holes burd
33、en-to-spacing ratio near 1.5:1 are loaded with light well-charges .Smooth blasting differs from cushion hat (1) the collar ,the charges are stemmed and(2) the perimeter holesare fired onthelasthesame roundastheprimary blast column loading is most common ,although spacers may be used .The holes are s
34、temmed to prevent the charges from being pulled out by the detonation of the previous delayed holes .Smooth blasting reduoverbreak in a drift and also provides a more competent back requiring less support .It involves perimeterndoesnormal Combinations of controlled blasting techniques are used .In u
35、nconsolidated rock,line sometimes is cushionblastingisn presplit or cushion boreholes . Corners sometimes are presplit 4 TUNNEL Themostcommonmethedofdrivingaminingtunnelisacyclicoperation Drilling shot holes ;charging them with explosives and blasting.Removingtheresultingmuckhree :Inserting the tunn
36、el o the newly excaved area; and advancing thesometimes is cushionblastingisn presplit or cushion boreholes . Corners sometimes are presplit 4 TUNNEL Themostcommonmethedofdrivingaminingtunnelisacyclicoperation Drilling shot holes ;charging them with explosives and blasting.Removingtheresultingmuckhr
37、ee :Inserting the tunnel o the newly excaved area; and advancing the ralls. arrangements,sreadyforthenextcycleof The basic principle of tunnel blasting ,in its simplest term, is to loosen a volume of the virgin rock such a t when it is removed the line of the tunnel has he correct direction s siblet
38、hecorrectcross-The dilling pattern in which the holes to receive the explosives are o the working face designed t :the holes are easy to drill; the minimurd ty of explosive is required ;and sibletotherequiredtunnelperipheryofthespaceleftaftertheblastconformsasnearlyA blast round consists of cut f, b
39、reast and trim holes . The cut portion is the most important Theobjectiveof thecutistoprovide afreefaceto whichtheremainderofthe roundmay The two general types of cuts are the angled cut and the burn .These can be used in combinations form various other cuts .Angled cuts are more n burn in wide headings ,due to the boles and less explosive required per foot .A disadvangtage is thrownfromthe sibility
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