TR 195-30 Explosives and Demolitions

8/4/2019 TR 195-30 Explosives and Demolitions

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EXTRACTS FROMTRAININ(G RJEGUJ.AT][ONS

195-10

EXPLOSIVES AND DEMOLITIONS

NATIONAL GUARD AND RESERVE OFFIOERS SCHOOLENGINEER BRANOR

1980-S1

'I'HE ENGIN.fI!ER SCHOOJ,Fort HlllIlphreY8, Vi"l!i"l~

1 9 S 0

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EXPLOSIVES AND DEl\IOLIIlONS

SECTION IIIHAjI,"DLING AND CAllE OF EXl'LO~J YES

ParagraphGeneral . _ __ 18Magazine locations ~ _ _ _ _ 19Magazine constructlon , ~_____ _ ?OMagazine opcrntlon ,______ _______ ____ _ '2 1~raD9portafion ________ 22'Old dynamlte .__________ 2:3Thawing dynatnite - --7- _ __ _ 24General precauttous w ith regard to explo81.v~8___________________________________ 2518. Genera1.-It must always be rememberorl that uxplos! vos ~1'(' never safe

unless handled with utmost eare, Carelessness lind rough handltnrr are IfkeJyto cause explosions and accidents. Never let "fll1ni.li(!.rUy breed ,'on-tempt,"19. Magazine locations.,-Q., A mncaatne shoutrl he i'.lcllted wlrh a view [0both. accessibiltty and safety_ A good location is nil isolated ruvine. D~lOplocations should be avotdedas much as possible, but when It is hnposslblo toavoid damp locations good drainage and proper vcntnution should he provided

b. When there are two or more magazines locnterl hi the SIIIllP "iciuity theyshould be separated as follows;

Pounds of exploslves SIIP3r:llion or tuagaztnosOver 50 Detached.Over 5,000 200 feet,Over 25,000 200feet plus 2 ' 7 1 1 feet for each 1,000pounds.20. Magazine conatructtou.s--. Permanenr magazines for hig-II exploslvr-sshould be bullet proof, tlreproof, weatherproof, and well ventilntod. For pel'manent construction magazines of soft brick or corruzated iron with saud-tlllo.lwalls are recommended, Brick for mauuzinv const ructlon should he n" solias possible conslsteut with good qunltty aurl dnrnbiltty in order til an,hl I;lr~'fragments in, case of an explosion. 'I'lie thkklll''':'' of sand wnlb to Nul'l'(against service uunnuuttlon should be about 11 inches. Stone, ""II,'rdl'. lindhard brick eonstructton are not suitable because of their dangerou traguientntion in case of nu explosion,b. The magaztnr-s should be carefully vontilnted by providing- npcnillg's jll~1

above tbe ground Iiue and just below the roof,r. Heavy sheet-trou sections make the most sntisfactory h'IllPOflll',Y lIIaSlIZilll'.d, Temporarv mnunstncs mnv be made to nccouunodnte morlenrtpsit.I'![ ~t,'ck.

of explosives in tile following manner:(1) In n dry bluff excavate II chamber of til" requisite slzo :11111iuilx-r t , o >

prevent cavlug,(2) In the open, on a light wooden frame, I}rt'etl'd on tlu- l'la'l1 of :I 1>0;1:

'house, with II wedge roof, construct n mngnz iue , ,1' light \wig-ilt ClIJ'I"lIg:lIt'


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2L JtIaga.zme operation.-a. Never store cape ill the same magazine wIth~ves.l ' J . Ai'IWYS ship old stocks first. Arrnnge stoeks so that, old stocks will be

rf'adily aeeesslble,c. Anow n o metal tools to be introduced Into the magazine.f,. Allow no matches, fire, lamps, er spark-producing devices in a magazine.6. Store eases of dynamite and other nitroglyt.'erin explosives right side up,

'm that the. cartridges will lie fiat and not stand on end.,. Do not store any miscellaneous materiar in magazines with explosive.fI, Keep the grounds around the magazine free of brush and dry Ieaves,

K~ a fence, preferably of barbed wire, around the magazine.A. Ne..-er open packages of exploslvas within the magazine, and use wooden

wedge and mallet for opening or closing packing boxes,i.Rubber or other soft-soled shoes should be used in magazine,j. ~"urn cases of dynrunite every 30 days, if practicable, when dyruunite i8not frozen.22.. Transportation.--a. Rail


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special type of double boiler shown In Figure 2 may b' used. Tbese boilers,come in two sizes, having 8. capacity of 30 pounds and 60 pounds, respecti..-ely .

. To use the double boiler, first see that the exploslve compartment isempty. Then heat the water to be u8e(l in a separate container. 'rest this' 1 " 1 8 1 : \ ' : 1 : " with tbe band until it ls as .hot as can be borne, then pour it into thewater jacket. Then add the-dynamite stick by stick. The double boiter shouldnow be placed in a barrel or box and surrounded. with


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u. Don.'t store or transport caps with high explosives,V. Oon't cut the snfety fuze short to save time.t(l. Don't operate. the blasting machine half-heartedly . Don't leave detonators exposed to the direct rays of the sun.y. Don't open a case of explosives in a magazine .. Don't have matches around explosives.4Cl .Don't force a primed cartridge into a drill hole. Have hole of ample.pt:!r cartridge.~ Don't handle safety fuze carelessly in cold weather. When cold it isSur ant! cracks easily. .00. Don't use a weak detonator. Use the, prescribed detonator or .R more'

powerful one.

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SrcTlON VPREPARATION Oli' CRA.ROES PllrngrllpbPrimers and priming". .---- 4.1

Priming with tHeyl cep and satety tnzL_ .. . . ~2Pr!mlng ".r~T blocks .. i3Priming in the elld ot aynam!te cartrtdges_ . .____________________________ 4,(Prim Ing In the ~!de ot Cfl:rt.t1 .dges . ._____ 41 '>Priming wltb cl",cti'ic tetryl enpH ~ . . .__________ 'I~Prhl'ing detonating cord' . .______ 47Sf mul taneoun detonation . . .______________ 48Wlrlr.g the electric etrcutt., . ._ 4!lConnections . . . ~_.__~_____ 50Testing 8 ctrcult.. --______ 51Locatfng a break ~ . ....... ...__ ..._ ...,_.,_..,.._____'2Computing reslstance . . . ~ .Splices, . -' __- . _Induced detonntton ._____ __ 55Preparation of bore boles .____ __ 56Loading hore hctes . . . .__ 1>7ampmg -- __ ---- - . . . - --.________ iii!~'lri"g . . . . . ....___ :;9

I J OI!iSlll1lS .____ _ . . _41. Primers and priming.-a. High explosive charges are USl1illly detonated

by a primer placed in the charge, A . primer is 1\ high explosive cartridgewith a detouarlng rap inserted. The uperntion of making and placing theseprimers is known as priming.

b, Primers should. be carcfuBy made=-(1) To Iusure the complete detonation of the explosive.(2) To keep the detonator from pulling out of the exptostve,(3) '1'0 guard against moisture.(4) To permit easy and safe Ioading of bore holes.(5) To keep the safety 01' Instantaneous fu:;;e when used from p1l1ilng out

of the blasting cap,42. Priming wit.h te~ryl cap AnJ. saiety IUZI>.-ll_ Cut off square and dls-

card 2 or 3 Inches of ftrze, Cut oiE It sufficient length to reach from the cha~ein the bore hole to at least sev;;rl!.)melle!! above tbe top of tho bore hole, Thiglength must be sufficient to gIve the blaster time to 'withdraw to a 'afe dlstaneaafter ligh t!ng the !;.'l'le,O. Reruoye one cap f~.:;mthe cap DOX by hand. Elhakc the cap 'Very gently to

remove Ilny cllrt in the open cad or the cuOl- If the end. of the rUt!> Is flatteued,ro!J it between the thumb iU~df'lugCl". SUp Ule cap gl;'lltly over the end of tbefuzc, so that the fIlZE" reaches down to .he eJtlli()stvecharge iII. tuecap. Thefuze must he cut square, A.n obliquely eut fU2.e may double over the powdercore and .-~use a m~sfi.n,. D not twist the fuze into the cap and do not useforce 01' violence when m"ldng the primer.e. When the cal' Is plaeM ov",r the fuze, fast(!D It securely in plll!"~ with the,~a:ocrtrupcr. Crimp tl~t' cap elose to Us open end; to make the crimp fartherdown rnl!;ht eanse an @xp!osion.d. Wh~.n the primel' is to be need under water. J~l:'ct(_


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the cap, l'eavIng. enough fuze between the knot and the cap to protect the capfrom any pull. Make this string fast around the Tl"T block.1M. Priming in the end of dyne.lDit~ ca:rtrldges.~. With the handle of rue

cap crimper or n wooden n\\'1 punch 8. hole strulght into the end of the car-tridge to!' a sufficient depth to receive nil or tbe copper shell of the cup. (Seefig. 22,) Insert, the cap wlth the fuze attached into the hole ,IHid fasten itthe~ with a cord tied first around theeartrtdge and then around the fu'Ze.To 'lIltl'rprooi this prhner etose the hole where the fuze enters the eartrrueewlth ,uny of the sealtng materials listed in parncraph 42,

1/ ; Another method M primIng til the end Is to unfold tile paper from theend of the cartrldgQ and punch u hole dll'c('tly into the center of th~ exposeddynamite. Close thl' Ioose rart of the ililpel: sbf'U 1U'(JUndthe fuze Dod tie ittightly.! ThIs method Is appUcRbh' tounderwater work when the tied end isTendered water- tight with soap 0.. slm-Ilar marertnl.e, Primln'" in the E'l1dhus the advan-tage of placing the iietonator In thl'

10. 22.-run~b bole WIth lIandleof MIl crlDlp~r RIO. !!3,--Pundl n hol~ III "ldl' o f curtrl


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46. Priming with electric tetryl caps.-a. To prlme II TNT block with anelt'


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(4) By using a tetryl cap and TNT block in whlcl::: an end of the detonat-lilg cord bas been inserted, !IS shown in Figure 29.

TN/on lJlock.~~

Ddooatill.jCordJ4Jj '"e!yJitrY/~./FlO, 21l.-[)etoDlltlng cord primed with ODetriton block

48. Simultaneou.s detcnatfono--Blmultaneous detonation or the detonationof several C'harges at U; same instant may be secured by the followingmcthods :a. EJeetrl.clty.

l). Electricity with detonating cord.c. Time fuze with detonating eord,a . Time fuze with Induced detonatton.e. Time fuze with Instantaneous fuze.49. Wiring the electric cl.rcu1t.~. Etectric detonation is readily divided

Into 3 distinct phases-wiriDg, testing, and firing the eleetr!c circuit. Thewiring is also divlded Into 11p;:lrts~omlecUng the detonator wires eitherdire

a knife blade; then join them with a long twist. {See fig, 30.) Make thistwist tightly to keep the electrical resistance in the joint at 11 minimutn.

FIG. 30.--Correet method of spHcing ~OI1i1Cct1ng lind dptonsting wires0. Before !:asteuing connecting or detosator wires to lead wires scrape the

ends of both scts : then bend the end of the lead \vlre back 'sharply and takeseveral turns of the detonator wire around the loop. (Sec fig. 31..)

~,,&~,/~z . .- - Ij~ J.~ -""",.....-Flo. 31.-A metbod of nttacbtng connecting or detonating wire to a lead wire

< l. '.r. conn~ct the load wires to the blasting machine, loosen the wing nutson the two binding posts lind hook the ends aronnd the binding posts; thentighten the' wing nuts on th_ewires. Tbe officer or noncommissioned officer incharge of the work should do this porBonally. The lead wires nmst not be con-

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nected to tile blasting machine until he has assured himself that the circuit iscomplete and' that no one is within the danger zone.e. It should b" the duty of It selected individual to remain constauttv at the

blasting machine to disconnect the lead wires from the machine immediatelyafter each shot and keep them disconnected except when a shot b being fired.

f. Naked joints in the circuit must be protected against short circuits. Tosecure this protection, tape all jotnts that are likely t.o come in contact wtthmoisture. - - - - - - - - - ~./ ~ ..~~ -~

FIG. 32.~Scries connection

- - ; _ ' _----,,\~FIG"33.-A stump blast connected ill sertes

50. Connections.-a. When nslnz a hlnstlng inachlno make all ennnccrlonsin series. To do this, connect one wir from ea{'h cnnrzo til one wire in thonext charge, am! ;;:0 Oil to the end until only the two end wires are left free.Connect these to HIe ends of lead wires. Figures 30 to s a give examples ofsuch connections,

b. Parallel circuits may be used when power or li;:::htillg circuits form thesource for the detonating current, Fir;ure:H ;;:how,,;such a cuuuectlon. Theblusr ina machine is not designed for, and should not be used with, parallelcircuits.

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51. Testing a drcuit.--'l'o test E ! circuit with the _,\lh'anometer or clrcuittester, touch the two lead wires to the r 0 binding posts arter all connec-tiODS except tho>' to source of power are ready for the blast. If the circuitis perfect, the needle will mono along the scale. If the needle does not more,there is either n break or point of lligh resistauce in the circuit. A slightmovement of the needle may indicate a. circuit which coutalns a point of.high resistance,52. Locating a break.s--Mnlce sure that the ends of tile lead wire are senn-

rated and not tOHei!!J]i: anything'. (SeD fig. 35.) Secure 11 piece (!f conuectlngwire N to end conneutlon D af the circuit. The wire must be long enoughto reach from joint . to joint. n, Hold. the bare end of N against contnctpost L and. connect contact post 0 either directly or through n second pieceof lead wire M to joint C. If the gulvanometer uow shows a circuit, the

-i - J .~ .1 .~ ~I 'I ,I"I II II :I II IJ L

FIG. 35.-:rt'~1iDgblnsrtng ~irenHbreak is in the lead wires and th y must be relJaired. If it does not showa circuit, connect contact post 0 with each of the- hare joints E, F, G, andH in suceession. If, for example, III ,';:.0 doing, the gnlvauometer sbows a cir-cuit when 0 is conuecterl wifh F hut one when connected with G the breakis between F and G. If the break is above tile tamping, repair it. .If itIs below the tamping, handle the pnrtleular shot irrvolved f\fi a misfire. (Seepar, 60.)53. Computing resistance.-n, 'Phe electric tetl'yl cap with ]2foot leads hns

It reslstnncc of 1.5 ohms aml reQuire." 11 current of O.:j,ampere, 'l'he lead wirehas a resistance of 2.!Hl ohm" per 1.(01)feet. To detel'llllne till' resistance of11 circuit, multiply the number ot' caps in the ,'il'cuit by ].5 aud add to thisresult the number of ].000 foot lengths of lend wrre multlplied by 2.541. Thenadd to this r suit the resistance of the Llnstlng' machine, 31}ohms.

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b. The voltage of the blasting machine is 45. E=IR, where E=the voltage,I tue current in umperes, and R tbe resistance in ohms. Hence I=E/R.Dlvide the voltage by the resistance, aud if the circuit cau be fired the re-sultuut I mast be over 0.4 ampere. Thus the total reststance in a circuit mustnot exceed 112.5 ohms if the blastlng machine is used. In like manner thecapacity of other sources of power can be computed with respect to require-ments of the installed circuit.

FIG.36.-Fuzc spllclng54. Splices.-a-,To splice time or instantaneous fuze or to splice instanta-

neous fuze to tlme fuze, cut the ends to be joined obliquely. (See fig. 36.)Be careful that no powder falls out. Place the cut ends carefully on eachother, dropping a few grains of powder between the ends. Compress the endstogether and wrap the joint with frtctlon tape. 'ro make two branches froma main, splice in the same way as above, cutting the fuze as shown in Figure 37.

b. '1'0 connect a branch of detonating cord to u maiu(see fig. 38), first drill priming hole completely throughIt block of TNT; then, at right angles to first hole,!trill through the block as many holes as there arebranches, thread the main through the longitudinal hole,pass the branch lines through the block from side to FlO. 37. - Begluntngside, and fasten by making rigb.t-angle bends at ends of ot double apllcecord.

c. To counect a branch of detonating cord to a main, the fonowing pro-cedure may he observed, but does not give IlS reliable results as that de-scribed in subparagrapb b. lfirst, slit the branch for a distance of about 8Inches with the cord slitter. Then place the split end of the branch as shownIn Figure 39. Complete the splice as shown in FIgure 40.

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A l~'"

J5 .r . \nchDet .C'oro to ho te lIsometrrc Vict \ )

Secf10nAAiFI(I., SS.-Detonntlng cord spliced. using- II block or triton

FlO. 39'.~Beglnnlng splice with cord

I'fomCI1P ~.G. ~t~aw'.,rI,~

C()rI~ectJointFlO. 40.-Splice with cord complete

55.. Induced detQua.tion.-Induced detonation is secured by placlng n blastingcap in a block of trlton and dstonutlng tuts by means of the mecbauical shock

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ill air from n charge detonated neal' by. It is of value in obtaining' siruul-tuneous det


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li. In drilling bore boles water i poured into t.he hole,making a mud of thespoil, which nets as n luhrtcant. This mud must be removed. In shallowboles this is done with the miuors ~pOOIl.c. After 41rillillg a hole to the d{'~ir{'ddepth in hard mntertal it is sprung to

form Il cbnmh r for tile charge. To ~prillg the bore bole, explode severalsruall (hnrg('s, OIlC after file other, ill the bottom of the hore hole untll tI('ham!>e)"of the desirorl ,.,iz(' is obtn ined. t~{'e fi~. -1-1.) Ample time must beallowed betwe 'a elHlr;.:ps for the bore bole to cool.

F!G. H.-Sprin:;lng II drill or bore 'hole

57. Loading bore holes.-Slill the cliarge tuto the hole and pre s it into placewith .fhl' t1lUlpillg stick. Place the II1'iOl(,1" last. Begin tamping the hole with Itsmall WIlU 01" dry paper. Then pour earl h 011 top of this wad. Tamp this

. . .....~.: " :~'". . . . . '... ~

!~~1~l~' , , : ;....

FIG. 45.-Li);ht tnmplue Immedlutely O\~. charge to protect cap followed byhe11vymn..piDg

FlO. 46.- Use of Wildof paper 8HHS [ISn sntety Iudien tor of where to stop illease tamp-jug must 1 > ( ' rerno 'Pll 1.>"~au8eof lDl8tlre

eartu ligbtly. 'I'hen add more earth aud tamp tinuly. using a wooden tampingstick. (See fig>l. 4'3 .md oW. ) When loallillb wlth dvuamtte, in f1ry holes.alwuvs slit till' ':ll"trillg-t)s (except the primer) just berore plucl ng theui ill thehole. 'this gi ves a inure compact l:bal'~C uud results ill I!reater efficiency.

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Rectangular 1 ICksof triton must be broken up in order to place them ill smnlldrilled holes.58. Taroping.--a. Tamping is the operation necessary to close a bor hole or

otherwise confine a charge. 'I'he mater-ial used in tamping is called "stem-ming:' Stemming should be free from stone and grit.

b. "-ater makes a fair tnmplng material, nnd in holes where the high ex-ploslve is covered with water furth r tamping may be omitted.c. .A . wooden tamping stick should alwavs be used. :An old broom or shovelhandle is ideal for small holes, while u ~trnigbt sapling can be used for largeand deep ones.d. Tamping Dear the charge should be light and easy, increasing in power

as the amount of earth between stick and charge I..ncreases. .Ful1 poweredblows with u heavy stick should not be used, butllreferably short, rapid blows. (See fi'g. 45.)e. VariOUS means of tamping are shown in anumber of the figures iIlu trattng the use of ex-ploslves, (See f;pc. X.) Or

governed by conditions. Wilen the electric taps and blasting machine areused, it Is saf for the bluster to Inrestigutc immediately. This investiga-tion should consist of II search for broken wires, faulty connectroas, shortcircuits, etc. Tbe lead wires should be dlsconnected before beginuing this. earch,ll. When cap. and fuzes are used, the blaster should wait at least 30 minutesbefure Investtgating the charge and, wlieu pussi!Jle, should wuit several hours

in order to avoid the po~sibility of beina Injured by a "hangfire n or delayedexplosion. If the charge is uutamped, Insert another pr-imer and fire a secondtime. If it is tamped but is in soft gr'ound, place another charge near by.Detonate this second charge, thus exploding the misfire.

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C. It is always dangerous to attempt to !:1'D1O\'ethe mi. flre, and every effortshould be 1m tie tv explode it by adjacem charges. l,Yh(:ll tuis is impossible,the tamping find charge should be removed ",cry gl:ntiy and carerultv with theminer' spoon,

J:'REPARATIO~ A_1D CALcrL.\.TlOX aT;' MIKE CH nGE~Bzcriox v I

Par .o : ; : r :rphMines nnO camoutrets .. 61Etr('cts of explosion , ... . _ -tDstermlnuttun o[ enarges und radlus "f rupture (of , .does .. ---________ 6::El~ctrjcal Hring of mhws .__________ 6461. Mines and camouflets.o-n. The destruction of an enemy's position, or a

portion of it, so that au attack mil. be made with expectatlon of success isthe primary object of underground wa rrare,which Includes in additton defense against ho a,til~ mtues, (See 'I'R 195-a3.) Surface worksare attacked br mines and underground work'!' I>yeamouflets, A camouflet is a mine so chargedthat tlIe destructi ve effect does not reach' th sur-face. The explosion of. a mine always revealsthe position of tile chamber by forming a craterat Ole surface, while experlenee has shown thatthe discharge of a cauiouflet is very difficuit tolocate. A au expl sion shatter t.lle groundwithin a certain radius of its center, it windestroy a l)ar& of the attacking works. us well asthose of the opponent within that radius, Tbisdestruction of one's own galleries and the attend-ant shattering of the ground, always difficult todrive through, are serious handicaps. Mln",s arcnot exploded without careful consldernttou of tbeconsequences.

b. Charges for mines and eamouftets arecarefully gauged to obtain the destred vadtus ofdestruction and 110 more. If undercharged, thedestructive purpose of the explosion i.s not ac-complished; -if overcharged, it not only wastesthe explosive but the consequent shattering or

even cratering of the ground will unnecessarily hamper further advance. Thedetermination of the slze of the charge is based on foul' factors:(1) Kind of explosive used.(2) Charucter of material in which charge is placed.(3) Depth of mtne.(4) Results sought.c. The charges for mines and eamoutlets may be placed at the end of attack

galleries and tamped by a series of walls Dud sundbuga, but preferably inspecially excavated chambers. So far aa jrosstole, all mines are fired elec-trically. Tbe size of the charge varies gr atly, aceordtng to the work tobe performed. Probably tbe largest single charge used by the AUles in thoWorhl War was approximately 50 tons of ammonal.

FlO. 4S.-Do&, leg

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d. An attack ga!lery is often given an ojfsct consisting 0 tWQ rtght-nngledturns jm;t before it reaches the polnt where a eamoutiet is exploded or counter-mining is expected. This feature is culled a . dog leg." Ii::;U Is !nte' ded toprevent the explosion from destroylng the maln part of the gallery. Th~nearest angle of the dog leg should be at lenst 25 feet from the mine chamberand the offset should be from 6 to 10 feet. (See fig, 48.)62. Effects of explosion.o-u. It muy be assumed us suf'H('iently exact for

present PUI'l)OSeS that charges of the same explosive develop tot{llenerg.!estJirectly proportional to their weights. 'l'hi.";energy is exerted in all dIrectionsi:the couuiresston of the surrouudlng medium. The maximum distance outfrom [he center of tile charge to which the P.XplOl;ion will de troy m1negntleries if; called the ro diu oJ' ru pturc, R. R. 'I'he surface joilljng the ends ofthese r:HU' is ealled the surtace of runturc.

b. If tile distance between the charge and the surface is le s than the radluscf rupture, the charge will lllow nut. fonuing !l crate". ~"hi relief of pressure('11 one side shortens all 1'[1(}ij ,)f rupture which have It ompouent in that.dir~ctioD, but does not appreciably u!ItC[those whlch have no such component.

DIG. 4D.--(JrmilS S J~tivu of typicu! craterBence when xn,uerinl Is u[splilced the surface uf rupture 1>1eUip;;oidal; when nomaterlal is l1isp!ilf'er!it iN sphertcal,c. The hole in tile surf'ace left by the blown-out material i~ eaueu u crater,T~,c dcterminutton of the crater whlch f1 pnrttculaz ehuruo in a pnrticular

place wltl produce, or whflt. (:!large uust be put in that place to produce thegiYell crater, OJ' >'i here a givc!>(')l!\rg must be placed to produce a desired.crutor, II re urnhlerns cousruntty ar-ising in military mining.

d. "lgurc;19 shows II cross section of a ty!)i."ll crater In earth. Thp. positionof the chal'g'", Is Indicated. A is the nrface of the ground; CD is tile Iinc oflenst reststance, commonty designated L. I. It., or in the furmulr- i ; DE i thecrau-r rndlus, and OE the radius of explosion. VRR is the vertical radiusof rupture and ERR the horizontal radius of rupture, All thp alaments of the-crater !lr reckoned with respect to the position of the charge and the openingof the origillul :;:-ro!lndsurface. TilL opening for level ground Ii:! alrniln r L,form to, and is approximately the intersection uf, the sphsrcld < ' 1 : rupturewith the ground surface.

e. Craters are designated us Qne-linea, t1v(l-linea, ete., accordlng as the diameteris one , twice, or three times the line of least rcststanee. L. L. R~ A two-Ilnederutcr is also culled a .:Jorm1l.ljn mine; less than two-lined, '1mael'cli.ar!le:l; and

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:001'0 than two- lined, ooerctiamea. As previously defined, Ii mine which doe"not break the surface is called a camoufiet,f. A common mine is recommended for a road crater. Under no circum-stances should It road' crater be more than three-line-d, for such craters havea very gentle slope and the road can readily be made passable again,63. Determination of charges and radius of rupture of mines.-a. Table II

gives a means of determining the necessary charge of one-half pound blocksof 'I'N'l' for a crater of tbe desired type, First, select the desired depthin feet that the charge is to be placed. Taking this as the value of t, cubethis value .and multiply It by the proper constant given in the table. When.the charge to be used is under 50 blocks, add 100 per cent. Wilen the chargeIs over 50 blocks and under 200, add 50 per cent. Wben the charges are over200 blocks and under 500, add 25 per cent. For charges over 500 blocks, add10 per cent:TABLE II.-Con8t(fnt.s tor (letenninin!J cha.rgelJ in one~haltPOu1ld bloel(',s of triton

and- radii of ruptltre tot mines

I c a , n o u J I Utldar-! oorn- I .let, charged, men 3,jinct-line lHllne Hine I-I-~I-I--------1.Jign.tearth_ ......... , _.,... 0 J W ! 0 . 0 2 4 1 0051 0.162 MUltiply by l' (or charge in on...haHCommon earth. "--."' . '" ,012 1 .03ll .006 I' ,18!i pound b18, ,0.% ,2$2 Caerges under 00 blocks, edd 100 perE~,.dpan ...... , _.. ,016 .016 100 . : r o o I' rent., . I Charg.s50to200bloeks,addOO per cent,

I Churges 200 to s o c blocks, add 25 percent.______ , .__ , ~::.ar~9S0ve' 5()O bJ,ocks. add 10 r~rcsntRadiusorruPtt1re{hQ,,"O~ta.L.1 ),0 1 L 4 1 ),7', 2..5 :t.~\lJt:tply these numbers byl ror ra-_______ ~'~'... 1,0 t 1.0 I 1.1. J,2 d,us IIIteet.

Kind or material

NlYu:,-MuHiply Ui;OH: constants ~aby 2 and add percentage as indicatedfor charge in pounds of triton. Divide the charge in pounds of triton by tlJerelatioe strenath. (see Table I) for charge in pounds of other explosives,

b. >'thel using the above table jm1grnent must he exercised in dassifying thesolt under the headlmes given. Experi",nce indicates that the table usually~ves an excessive charge for the ref;ult!ii-indteated RtHI that tabulae chargescan be reduced after experience jjHS been gained as to character of tile mutertalin which the charge is placed and best "manacr of utilizing the explosive em-ployed. In thts connection it should be borne in mind that tn military miningwhen explosives are plentiful an excelleut maxlm foi' tl19 first charge is do 1Wtsprll'c the powder. Every charge 'lIould be carefully observed and futureeconomies made iJ' practicable,64. ]:}'ectrical fhing' of mines.--(I. In Inrg mines two complete firing circuits

should hi: iwlta lled, so that If one fails there will be another available. As thesuccess of the mine dlJPNl!i8very Iargely on the proper placing and tamping ofthe churce. the othcer in immediate 'charga personally supervises all loading.b. 'I'he bulk of the e),,"Ph)~iv{' o t an mdlvtdunl mine is not taken to the mlneshaft until the mille is to be charged. 'I'be matertal is car ried into the trenchby working parties 'and deposited at mine "haft:> or other pl:lces i.1Hlicated bythe officer in charge. Where large charges nreused, special mine chambers m:e

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cut to the exact size' required for 'the calculated cubic contents of the explosive,if practicable. In the event of the charge, solidly packed, not entirely fil1lngthe mine chamber sand bags fined with clay or earth' are used to Illl It com-pletely, The charge should ,be carefully packed in the chamber and primersinse~ted to 'best advuntage, dependhig on size of charge and number of acto-nators used. I-land electric torches are used while at work. No candies ornaked lights should be allowed ill the vidnity. Lead wires are connected withthe detonators and carefully hooked up out of the way, usually just under thecap sills. Plenty of slack must be allowed for these leads, so that detonatorsmay not be jerked out of primers or charge. They are carried up to the dugoutor trench from which it is planned toure the mine.c. l.'be tamping should be vefYthorough. Sandbagstllled with clay 'or earth are

excellent stemming- material. Tamping should be carried for approximately20 to 30 feet from the charge; then leave au air space of perhaps 12 or 15 feet.Place sandbags for another 20 or 30 feet and continue with this alternatetamping and air spacing until the thickness of the tamping is not less than thehorizontal radius of rupture. The tamping required will depend on the si~e ofcharge and other condtttons encountered. ]'or camouflets, if time allows, tampto a distance of twice the calculated radius of rupture, Strengtben the tamp-ing by pieces of timber, crossing each other diagonally, and with their endssecurely jammed Into the stdes of the gallery. The air spaces should be ,ap-proximately 20 per cent of the whole tamping. The tamping is done by aselected crew of experienced. miners, Various devices are employed to keepthe enemy gnessing while loading the charge and tamping. In laying chargesin clay the utmost quiet must prevnll, and every precaution possible to Insurethis must be insisted Oil. ,The floors o.f the gaUery should be covered. withsandbags. Blankets can be hung at various places along the galleries todeaden noise. Minel.'s must wear canvas shoes or work in theh' socks. Talkingshould only be allowed when necessary and then in as low tones as possible.Only the officer and necessary assistants should be allowed in the gaUery attime of charging.d. All connections must be thoroughly tested before chargiog, and :I f firing

the mine is delayed, whenever it is decided to fire, The detonators, electricleads, and exploders are usually tested before being brought up to the trenches,but this is not always possible if Underg~Qund fighting Is in progress. Tileofficers on duty in trenches must have 1 1 1 ; 1 adequate supply of all electricalequipment on hand, together with testing apparatus, In order to he preparedfor anemCl'gency.

e. Itis the usual practice to locate a magazine underground in some centralposition. A large supply of high explosive is maintained there in addition toall accessories for tlring. Portable or mobile charges, generally from 40 to 50pounds, and other high explosives are kept In these magazines 'or placed invarious main galleries in safe places. ,These charges are made with primersand detonators in place and with 4 to 5 :feet of safety fuze attached. In theevent of breaking into enemy galleries' or entrance by the enemy these mobilecharges are immediately ready for use, and the fuze needs only to be lighted.f. The most common mistake on the part of officers is to fire their mines toosoon. Coolness and good judgment must' be used. Mines already charged arefrequently left for days or even. weeks before firing. Care to prevent moistureor water reaching the charges. must be taken. All detonators Ilre.very securely

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wired to tile el!~ctrlc lead. wires, Insulated tape being then wrapped around'conneetions, followed by Uquld robber solution liberally applied over the wholesurface of tape, The electric leads are mmally rim out from reels, which admitof their being laid bandHy in the galleries. From the mouth of the Bhatt theyare carried to the firIng dugout and are bung up In a ilara position unttl the-mine is to be fired, when the leads are connected to the blasting macatne. Twoblasting machines are used, and both should be pushed down hard at the samemoment.

g. Orden to toad charges 01' flre mines are: given by the resporu;tble officer,and only in the event of an emergency are subordtnatea allowed to tlrn mineswithout orders.

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SECTION VIII

CALOULATION OF DEMOLITION CHARGESParagrapbCalculatlon ot breaehmg cbnrge________ __ 6!l

Chart tor sotutton of rormula N=R'KC .________ 70Shuttering charges __ __ __ 71DIstributed charges .___________ __ __ __ 72TJmber . .. ._. . ._____ 73Steel . '__ 74Reduction from TNT to other explo.- in:s________________________ 7569_ Calculation of breaching charge.-a. The ra(/i2111 oj l'Upt1!I'1) is that .of a

sphere within the surface of whicb a charge ot explosive will completely shatterand displace all material. 'I 'SIC ractue of rwpture is designated by R, R., or R,in formula below. (See also par. 62.) A breaching charge is a charge sufficientto blast out a cone of material of which the charge is at the apex and the basehas It radius equal to R. (See fig. 50.)

I I! ",-Zn . -:, !

FIo. :SO.-Breaching char-ge . .b. The following formulas give the amount of explosive required for abreaching charge:(I} N=R'KC+25 per cent for charges under 100 blocks.(2) N=R'KC+I0 per cent for charges over 100 blocks.

N=Number of one-half-pound blocks of triton required.R=Radius of rupture. FIgure R as the d"pth to whIch dislutegrutlnn is

desired, measured from the center of surface of contact betweenthe charge and the material to be destroyed,

K=A factor dependant upon the material blasted.C'_~A faeto!' dependent. upqo the location and tamping of the charge.c. Values ot .K are as foUGWS :

- - - - - - - - - - - - - - - - - - - - - - - - - - - - -I R I_ _K _Material

Poor masonry, .. . _. ._. ._. ._. All values ... __ .375Good mas"nry, concrete, rock, .. . . ._._. ... Under a r e e t _ . : _ .6253 wHeat___ .506 to ?fret .. _._... .438Over '{ 1001.. . _ .375U9C se concrete, first-class lD!lSOnry ~ --- lJuder 3fect._____ _813 to [, reet. __ . fj;;5 to 7 reet, ._._ .57l over7feet-----.-- ,49ReIDforcedcoucrete. ._______ __ _ _ _ _ _ _ _ _ _ _ _ Cndsr3feet_._. 1.25_. 3 to 5 t e ~ t . _ ~ _ _ _ _ _ _ _ 1.00I ~ to t [ OO t_ - -- -- -- - .83. 0,,& 7 f e e t _ _ _ _ _ _ _ _ .75

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rf. 'rh~ value or C depends upon the ilwntion of tbe charge ana tbe extentof tne tamping, {) equnls 1.0 for charges placed In a bore hole and thorough! s 'tampe(l. Fur eharges plal'ed against a masonry wall but not tamped, C=4.5.Thor l1~h tamping gtves great et'OI1IlOlY in the use of explostves, 'l'he actual'fuiue 00 1 '('ted tar C wtll range betw!'en 1 ani! ta,:and tIle selectioa of " propervatue depends Inrl!:ely on the expertenee of the Must r. FIg;:i'e 51 snowstypical lo!!dj!l.ir~with the propel.' vntues of C selected.. It un,,, he uudeestcod that the abo'!'.? formulas gl.e only approximate re-

snlt~. H. will usually be found that th.. charges derived ff'JID them are ade-quate for the work d',lIirNl It should be borne in mind that for militarydemolitions an excess nf explosive should be used for the first charge 11 0 as toInsure complete destrcetton. E~ery d.iurl!;e should be NlrefuUy observed nodfuture economles in the 'lRe of el"pi s:n's made 'if p)lv~lj(s.ble. Sim'ilar remarkslire applknblc to the demotlttons formulae given ill parll.gt:uphs 72, 73, and 74.

TlI.m.i)(',;! C'LO(In!:..mpm C'~6

Th.~C1.:;{lpt~proC"U;Flop 51.-......f~Jo~sr.( C

' 7 < 1 Ch:;.rt for lrohltion 0 f iOtID.'ll,.. N'-=IL-'riC.--(!. Charts I, II, ann III mayb used to ;;o[\'e tbl?'formula N=.n'KC for Vll.IUfflof R rtcrrd 1 . to 3(; f:;et.,> ' I . To use t!:ten. dmrts-(1) Place a stratgbt etige bori7.cntalb' at toe pwp1E'r "lilue (,t R.(2i Whel1) the ..tratght e;'lgtl Intersect the rune IAheled R O , drop R nnE'

vel:"l.kally to Inteesect the Iine lil.hel~a wHh the PI'OIJel"value of C.(3} I'rojCt tul pn:lt of intersectlon borizv!ltal!y to inter eet the line

labeled ~ith the . eleetNl value of K,(4) Pl"ojet this point ':~ttie.lly Ilnd l"elld on the ;.;ea.ieat th e top of the

chfnt t e value of aKe. If tbi~ amount. is ~m!ler 100 blocks, add~'j per centto ;,:'("t tne proper chn1:~('. If' rtts OViOr100 bloeas, adc 10 PCI' cent.'(1. Shatte:d.!lg cb&.rgc:c;,--~batt."i'illg-chur5(~i;l,.!,IYel' from breachlng chnrge:;In that the material 1 < ; ; onl, l(lsell~d and Is not b~[i~tel! II'Vr! y. Such cnargesart> 111"(00 in qU!l.i'rying, 8f.1an !ltd to meehantcat demclrtlon, and in mining.'I'he ~hfl.tte"'ll.lg I;:(fect c3:.teu((f! from one and ~ :ullf to two timl?R the radius ofrupture, F!r;uN; 152shows a breachtn.-: cb.&l'~'i:to the left and a fihett~\'ln!,:charge to the 'ri"ht. ~igurs!iS 8 :J .OWS a charge facoo in 1\ countermine to


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)i\l{"C[ 1 ( 0 . ilb blacks TNT

40hample:"hen 'R"3's' t'n~trK -O .5 0 ( < lo od U \a .S o ut'9 R . be t'I I Jem 5a .nd .5 )C'-i,O IsHma.tc or Conditions.$ta.t'"i i l l._g ~t : a : , r(a.dLI1StoD. w'e: tod'and toe""AtU( of N ')"n:." el6.Add 2570.U3e l081110clu TNT

(~'Il.cep, 22.) No, 1


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. R ~ K " ( ' ; "No ;o li'lb . H o c1ts TNT

(Face 1), 22.J No.2


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C h a r t ill;o:~tt\pt'lWuet\. -.25'KO.3ZS (for ..Tha.1e)


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destroy It hostile drift. '!'his charge must be kept at least 2 R below the surfaceto avoid shattering the surface of the ground.

FIG. 52.-Breachlng churge to left, shutteringcharge to rig!!t Fm. 58.--Mlne ChlWl:2 or camounet

72. Distributed chargeso-=Dlstrtbuted charges are charges placed in a con-ttnuous row or chain exten.ding the er tlre length of the slab or wall to bedestroyed. Such charges can be detern.med from the formula:

N=3.2 R'KC per yardwhere N, R. K, and C have the same significance as in paragrapb 69.1 < ' u 1 ' reinfor-ced concrete, R should. be taken as one find one-fourth times the

thickness of the slab. Charges ill chains or rows require about twice as muchezplostre as concentrated charges. Their use is the exception, find should berestrlcte ..d to demolitions of thin slabs or walls. Sincc detonating cord is sub-ject to deterioration which is not apparent to the eye, too much depend-ence should not be placed on distributed charges which are to be set off b;rdetouating cord.delayed until a given moment and tben executed at once.

b. Single charges are computed as follows (see fig. 54) :(1) External charge:N = . E 20N=Number one-half pound blocks of triton required,D=Least diameter of timber in inches.

(2) Internal cuarges :N= U'125Nand D have same values us In (1) above.

c. A ready rule for triton blocks Is to allow 8 blocks per square foot ofcross section for external charges and 1lh blocks pel."square foot for internalcharges.d. External charges should be placed so that adjacent blocks are In contact

with each other and with the surface to be destroyed. It is advantageous toplace trtton blocks witb their long axls perpendicular to the plane of tbe sec-tion to be cut. Itis important to concentrate the charge and assure completedetonation. For the sizes of timber usually encountered girdling is unim-portant and can not be effected without sacrificing tbe considerations enumer-ated above. ~

e. The above formulas should be used for cutting piling. When practicable,an external charge should be placed below water level, as water acts as II.tamping agent. The charge may be attached to a board, shoved down to theproper depth and the board then lashed in place.

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74. Steel.--a. Bessemer steel crystullizes, breaks, and throws its fragmentsaway from the explosive. Open-hearth steel tears and may throw frag-ments in any direction. These fragments are frequently large and may bethrown with force enough to carry them from 400 to 1,000 yards or more.Extra precautions must he taken to shield the firing detachment. J

b. F'or the purpose of computing the untamped charges required to destroy Ibeams, built-up girders, columns, etc., the following formula may be used:

N=%, A .where N equals number' of one-half pound blocks of triton required, and Aequals area in square inches of the cross section of the steel member.c. To cut a steel member, 'Place along one side of the desired line of rupturea charge of triton. The blocks should be in contact with eachother if prac-ticable. If the form of the member is such that the charge must be dis-tributed on opposite sides, the opposing portions should be offset so that their

Dlameter=30".D'Charge (N= 125)=7.2 blocks TNT.Blocks are broken up to fill bore hole.

FIG. M.-Charge~ for cuttIng tImber ,action will combine to produce shear. The portions of the charge, lr directlyopposed, will tend to neutralize each other. Built-up members present specialdifficulties in that they are frequently of very irregular form and that itisdifficult to secure close contact between the explosive and all plates. Theabove formula is applicable provided the difficulties can be overcome with thecharge indicated; otherwise the charge must be increased. Elxperience indi-cates that if a tamping of moist Clay is employed, charges may be reduced 50per cent provided the explosive acts upon the entire section to be cut.d. Railroad rails can be cut by one or two blocks of triton tamped with looseearth.e. \Vhen the aestruction of a reinforced concrete structure involves a two-

phase demolition in which the concrete is first shattered and removed, afterwhich the reinforcing bars are cut, the following formula for cutting thebars should be used:

N=2AN and A have the same significance as above. In general, each bar mustbe charged separately. In some cases, when the bars are small, one block,placed between two bars. may suffice to cut both.

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741~. Concrete, plain and reinforced.-a. The destruction of plain concretestructures presents no special difficulty. The members of such structuresmust necessarily be subjected only to compressive stresses. It is necessaryonly that the charges used shatter the concrete and displace some of theshattered material. The formula in paragraph 69b, with appropriate valuesfor K and C, will give adequate charges.

b. Unless very large charges, much greater than found by the formula inparagraph 69b, are used on l:einforced concrete, the result will be to shatterthe concrete and to leave the reinforcing practically undamaged. If plentyof time is available and explosives must be conserved, it may be desirablein the demolition of certain reinforced concrete structures to first shatterand remove the concrete surrounding the reinforcing steel and then cut theexposed rods by a second series of charges. Howe'il'er,by attacking that partof the concrete which is under compression where the bending moment ismaximum and where, also, the reinforcing is least, the structure will prob-ably fall, due to its dead load, without having the reinforcement cut byfurther charges. The charge should be placed 50 that it will shatter theconcrete in compression and. that the force of the explosion will act in the


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SEOTION IXD:mt:OLITIONS ParagraphPurpose a n a obj~ ~_______________________________________ 76

Methodo ..: ~..__~__ ::.. .. ,__________________________ 71

! : ~ : n ~ ~ ! = t 1 ~ ~ ~ = : = : : : : : : : = = : : = = = = = : = : = : : : : = : : = = = : : : = = = = = : : = : : = : : : i:xecution ot 'a demoUtion -' .,.__ 80Objects subject to deiDol1tioll_________________________________________________ 81Roads .. ~'~ -_-- 82Bridgeil .., ..:_________________ _ _ 83Railroads Telegraph and telephone Hnes ~_________________________________ SUFrame buildings ..: --------------- ._____ 86lVeI18 .. ~ __ ~________________________________________________________ 87A r t i l l e r y _ _ __ __ __ _ 8 8Un6ltploded .hells Rnd bombs_________________________________________________ 8UDemolition pll!.n8 :. .: ~__~ ~ -'- ,__ 90W i r e e n t a n g le m e n t s . . . . : . . . . , . _ _ _9 1Bnngalore torpedoes _--- . ~ ,_________ 9276. Purpose and objects.-fl. The purpose ot military demolitions is to de-

stroy or make unservteeable flny object in the theater of war, the preservationof which would be unfavorable to our own troops or :l'avora~le to the enemy.Objects protected by international agreement or the laws of war, however, arenot destroyed.

b. The principal objects of military demolitions are--(1) Natural or artificial objects ha'l'ing no tntrinslc or permanent value,

such as accidents of the ground or purely military structures.(2) Natural or artUicial objects having Intrtnste or permanent value andadapted to useful purposes In times of peace, such us buildings, bt'ldge!l, etc.c. Demolition of objects having intrinsic 0': permanent value Is psrmtestbleonly under a strict military nec-essity. Such demolitions should only be under-taken in an emergency and when explieltIy ordered by competent lI.uUlOrity.a . The subject of demolition is primarily within the province of the engl-neers, but itshould be familiar to all line officers, &s the area of operationsis so extensive in modern warfare that engineers are not always available toperform the work. Consequently all combatant troops are supplied with demo-lition outfits and instructed ill their use.77. Hethod!:l.-a. Demolition may be accomplished by fire, water, mecnanlcal

means, artillery fire, or by charges of explosives. 1_'ue demolitions hereintreated do not include those made by fire, water, and mechantcaljneens, asthey are simple and too varied to permit detailed description. Neither does itinclude demolitions accomplished by artillery. When it is possible to placecharges of explosives judiciolJsly, the results are more effective. more certain,and more economical than those secured by artillery fire.o . Deliberate demolition will be employed when'ample time is In'Il1labie tomake thorough reconnaissance and careful preparations. Economy of materialis of considerable importance, and partial failure may not be serious, as thework may in many C8,8eS be completed in a second series of operations.c. Hasty demolition will be required when ample time 1800t available tomake careful preparations. In this form economy of material is of secondaryimportance, as failure to accomplish the mlssion is UDpardonable. Ho,rever,

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in all cases, common sense and good judpnent should be used, since the ques-tion of supply, itnot cost, makea it lmportaJ!t to avoid waste,fl. Structures should be attacked at their most vulnerable points, where the

minimum of demolition will involve the maximum effort for repair. Forexample, on a :railroad It Is more effective to demolish a large bridge than toexpend the same amount of labor in demolishing the track.78. Points for hasty demolition.-For hasty 'demolition and for cutting

girders, etc., to o following points should be remembered :e. The blocks of triton or other explosive used must everywhere be in contactwith each other and with the object to.be destroyed.

b. The charge as a whole must be ftrmly fixed to the obje(.'t, and if possibletamped.c. All ruaes or lead wires and detonators must be prOPerly arranged.d. The largest portion of the charge should bo nearest the greatest cross

section.e. Use plenty of explosive.79. Asll1.lrlng detonation.-a. Alternate methods of firing charges shoull}

usually be installed. Operations in the "reCentwar have shown the danger oflong Ieads for surface demolitions, 8.S they are often cut by shell fire, .andelectrJ..:al firing should be used only when essentiai--e. g., for simultaneouscuttlng' of severa! girders of a brIdge.

1 I. Fll'l.ng)by time fu:r.e is the. best method to adfPt during a retreat, as oncethe charge Is placed a box of matches Is sufficient to detonate it.80. E:rroeution of a demoUtion.--a. The execution of a demolition requires

an estimate of the situation, a decision as to demollWm to be employed, prepa-ration of a bill o~material, preparation a!ld placing of charge, and firing.b. 1.'he estimate should cover the followmg points:(1) The ()bjeet~(2) The time Available.(3) TIll) extent of demolition necessary to falfill the mlsslon,(4) The possible Ioeation of the charges, aC


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82. Roads.--a. If the object Is to delay the enemy temporarily, roads maybe rendered impassable by l100ding when practicable; by telling trees aero theroad; by placing abatis or other obstacles; by placing barricades in the streetswhere a road passes through a village; or by dlsabUng the Important bridges.

b. Road craters form efficient obstacles itthey arc made at points where themaximum dislocation of traffic is produced. Where deviation of traffic ispo isiblc, road craters are worthless. Oonsequeatlv, they should be made Inembankments, cuts, fills, causeways over marshy ground, at crossroads, or invlllages, Itno side roads are left open. (See fig. 5.') and par. f\3.)c. AS trafiic must be matntalned during the period of preparation, tunnel-ing under tile road will be necessary snd may require ODeor two days' work,but tor ha ty demolition it is often possible to utilize culverts or existing dug-outs under the roadway. It the ,crater 18to be in the vic.illity of avlllage, atunnel mny be driven from a cellar or well, but if these are nut available asmall verttcal shll.ft should be Bunk at the roadside and a chamber drivenfrom the bottom, The ~b8ftsand tunnels win generally require timbering,(See figs. 56 and 57.)

M2I.tcrial- I~'I~ ;).l1d cl'whe4.klrrl VJJIUI! Q /'C'flIr (;f)lI1I1U'11 111,,"il l I lImdp :z n.Charge; N=C I' + 100%. (See par. 63.)

C-O.I0. 1~6'.N=.l (~Hl}-21.6 + 100%.N= 43 block~TNT.Tamp thcrougaly.

F1G.51S.-Road mined. Charges can be determIned all explained.in parngraphs,63 and 69.83. :Brldges.--a. Bridges are natural objects tor attack, as reconstruction is

usually slow. As the difficulty of repairing bridges when the abutments are,desh'oyed illmuch greater than when. they are intact, the object of any bddgedemoittton, time being available, should be to destroy the approaches andabutments as well as the bridge itself. This Is especially important It IIgetour Is impossible.

b. The best Wfll' to attack I> bridge approacb 01' abutment Is to place alarge charge under the roadwl!Y close behind the abutment. A .. tunnel maybe drIven. it tile apprcacb is an embankment j, othe.l'wise 1 1 . shatt should be sunkby the yoadwa.y and it chamber dr:iVeJl from 1t t o the center of the road.e. (,'harges may be computed as explained 1 J l . parl!gl'&phs 63, 00, and 70.a . VarloU8 types. of brfdg,e demOlitions, areas, follows:(1)' Light wooden bridges m a y be eut ~W1l with saWII or axes ; sprinkled

with Ini!ammable 011 and burned; palled fr9,m tte abntmeata with tackle orciemoUahed. with exploBives.

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(2) Ponton bridges may be hasti'lY d.isRbl{!dby cutting loose the center baysand desuoying or sinking as mnny boats as possible.(3) Suspension bridges may be destroyed by cutting the main chains or

cables at the saddles over the piers, if these points are readily accessible, orat the anchorages.

(4). Mllsonry bridges of all kinds can be efl'ectlvely destroyed only by usingexplosives. Except fol' reinforced concrete bridges, it is feasible and desir-able. when time is available, to cut deep chambers into the masonry, placethe charges therein, and tamp them thQroughly. Charges In one-half pounds,Jf' triton for masoneg structures C!!!2 be determined by formulas given in para-graph 69 and from Charts I, H. and III.

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(5~ A masonry arch may 00 4i:Vllollshoo by piaclng charges of expl;}she alongthe haunches or at the crown. Ift " . :m , { l iii very' limited and the 1'oadway neednot be kept open, a. charge or ".luu'g-ea pl!l.c6li on the l'oll.dw!ty form aneffective method of demollti?u. A :ral"atively la-l'og9 amount of explosivewill be required, particularly if there is no time for tamping. The demoli-tion is generally us complete as wh~n charg-e& at the haunches are used.In the case of a reinforced concrete deek gird-fl!'span the chaZ'glls should beplaced at the mtd-pcint of tbe span, so that the dead weight will cause itto fall when the concrete is shattered. If the charges are to be placedsome time prior to the actual. destruetton C lf ~be span and the roadway mustbe kept open in the meantime, they must be located underneath the span.Such placing of the charges freqtlentiy tckes '" great deal of time. Caremust be exercised to place-Ule various charges eo that the concrete in com-presston is shattered. An equs.lly efi'ective and Itl.uch mere rapid m..thod isto place the charges, tamped or untaarped, as circumstances indicate, onthe roadway over the beams. Figure 58 shows Ii. girder span prepared forqmnolitiOD. by a combinaticn c the two methods outlined above.

({i) The most complete demolition of' a reinforced concrete arch bridge isobtamed by attacking the piers. In the case of a .multiple arch bridge,the destruction of an intermediate pier causes both of the adjacent archesto fall. Because of the massive section of a pier, lar.ge charges are requiredunless the pier is recessed to receive the charge. Sometimes piers are madeholtow and :filled with sand. It is only necessary in such cases ttl cut ahole through the shell and detonate a suitable tamped charge placed deepin the filling to completely destrov t.:uepier.

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(7) FroID the standpoint or economy of time ana explosive and complete-ness of destruction, the best method to be rollowed in the demolition of amultiple SPall reinforced cpncrete deck girder bridge is to attack the sup-porting bents or piers.(8) To destroy pUe bridge's or similar structures below fhe water line, com-

)Jute the charge, bind It secnrely to a board, thrust the board clown beside theplle unttl the destred depth Is reached, and lush board against the pile and fil'e.(II') (!I.) To ile~troy steel truss or girder bridges on masonry pi!'l's it ill

often be sufficient to demolish the piers, if they are hIgh, as thetrusses or girders in illl!ing wlll be rendered worthless.

(11) However, it is frequently ea Ier to cnt the bridge members than itis to demolish the abutments and piers. If possible, it is pref-eruhle to cause the slmnltaneons destruction of at. least one abut-mont. one pie!', and It span, (See figs. 59,00,61,62, and 63.)Tij'l1tened ! z Y RackSUck

-~, .

1:!'xo.35"=4.20 sq. In.~(~.(lO-O.:~5) (0.35 + O.731!)~5.06 sq. in., 2TOtlli=!!.26 sq. In.nX9.2ilr=6.9-l blocus.Charge: 7 bloeka 'TNT.

FIG. 59.-n.,SIl"~ticn of 6t~(>1I beam, ellowlng calculation of charges and wedging(e) Tbe main trusses should be cut Dear the abutments, lind care shonln

be taken in placing the charges to facilitate the dropping of the-span,(d) ,ytWTl' it bridge bas (>~eral spans, the longest one should be de-

stroyed. Ifthe spans are of equal length, eUher destroy the one wherethe stream Is dPE'pe~ and swiftest or the one nearest tbe enemy.

(e) Cbur!!:!'~for cutting steel must be llrmly placed against the memberto he cut and held in place by boards, wlre, or wedges,

(f) In case of emergency concentrated charges of high explosive may beplaced In contact with the tension members of the cborrls.(u} Where bridges have been demolished i)y the enemy, CtI.1'efulsearch

should be made for delayed action or contact mines on elth(:1:'stdeof the abutments, aa these mines arc sometimes place{! by theenemy with tile object ot causing casualties when the constructionof new abutments is begun,

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(10) The engineer {)f\lcer will have to exercise careful judgment in deter-mining jm~t how much of the bridge must be demoI1Bhed to cause the enemy.the necessary delay. The extent of demolition necessary d pends upon thft.nature of ~he construction, its heig'bt and span, the nature of the approach, andwhether or not there exists an easily accessible approach in the vicinity .fur.a temporary bridge,. He will frequently be confronted with the problem ofwhether to destroy 2, 3, or possibly more bays. This decision will depend uPQil-(a) The tactical situation (how long the enemy must be delayed}.

(b) PosslbiUties of rapid reconstruetion (whether or not the enemy maynse the remaining piers if ooly the spans are destroyed).! ! . h t e n ~ d qy &ck Stick

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a DeW temporary bridge, Destruction of greater extent than this is usuallya waste of exploslves. If it is carried only to the point where it would take,the enemy jnst a.' long to repair the' damage as to make ,II temporary structure,itwould be to hls udvantnge to choose the former procedure because the result-ing bridge would usually be stronger and more reliable,

- I -1 ~~L . . , ~ . _ , : ~ - E ~ li I IA=2 X 2.56=5.12 Sq. 111.

N= %A=% (;:;.12)=3.84 blocks.ChJlrge: 4 blocka TNT.

I:---------.z~li*-------_o>.IU.:J"X2"X4=13!!.O sq. In.35" X 2~'=iO.Osq in.Total=202.0 sq. In.

% . X 202=1::>1.5 blocks.Charge: 1;:;2blocks ~.lilG.61. -Destructton of buil t-up girders, &howingealeulatton of charges and wedglng

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1I~ - -- - - - , ~r- -- - ,! I I I I1-- --'

I -- -, ,) I I I 'jt ' - -- -'I r -r ~ - -- - " ' 1If-'-'-'

(201/.," - * ")X %"'=7.-11 sq. Ill.sX %" X 2=6.00 g'J. in.(3" + Z% , U) X % ," X 4=_5.73 sq. in.'rntill=19.16 sq. in.% X 19.16=1L:J7 blocks.Charge: 15 blo~ks'l"N'l'.

,--..aI__ ._b_\5j"xj S ",'~_.-,",.-.....-,JiZ.-+--.~I-r : /:IL ._iI ---.-------.~ .....? ------.-----:>o!391h~1 X : : ! ~ ,~~f)8.88 sn, ill.12" > < 1" X : : ' ~ : , . : : . . . ; : : : 2 Li)(J ~j]. in.~6H+ !j':h") X :!~'J X -"--=11.2li sq. tn,

Totnl=1!;O.13 sq. in.'4 X J30.13=,07.G blocks.Charge: 98 b!ock", 'l'Yr

]l'w. 61- (Continued) .-l)e.rrnictloll of ballt-up ;;j:-r.er~. ~howinK cLlJ,'u;3Iion ofe!t:lrees s.n(f Wedg~Ilg

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84. Railroads.-ll. (1) Railroad trucks may be temporarily disatlled by dis-tributing men along a section of the line :md overturning it, preferably at an em-bankment or till, or the Ilshplutes may be removed at one end, a beavy chainfastened to the track, and the entire track pulled up with a locomotive. The

ties may then be loosened from the rails, piled, andburned. The rails may be thrown on the fire andtwisted while hot. Figure 64 illustrates a lever fortwisting railroad rails. If the demolrtion is madeon a curve, the repair of the track will be moretllflicult, as curved rails are harder to replace thanstraight ones.(2) Trains may be wrecked or delayed by remov-

ing rails or by cutting them with hIgh explosivesand camouflaging the break.(3) A considerable extent of track may be de-

molished in a short time by employing a squad of8 men and a push car loaded with. high explosives,detonators, fuze, and. wire. The car is pushed by

\2 men while 2 men prepare the charges. detouators,Flo. 64.-Lev.,r for twiatlug' amI fuzes, and hand them. together with the neees-rallrond ralls. sarz wire, wedges, ete., to 2 men walking beside

the car, who properly place, bind, and tamp them. Two men fol1(>w at ndJBtance of 2(".0yards to detonate the eharges.(4) If two charges are used to cut out n section of rail, they should hI"!

placed on opposite sides, at a distance of about 2 feet from each other, to gaina shearing effect.

FIC. G5.-Charge for destroylDg rnllway tmcts'(5) Figures (;;')and 66 show methods of placing charges. One or two blocks

of triton, tamped with loose earth, will break railroad rail. (See par. 74.)o . Blocking a tunnel effeetively interrupts ratlroad traftlc, Arrangementsmay be made for a. head-on colllston at the center of tbe tunnel between It ear

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or locomotive and II moving locomotive or the tunnel may be demolished brplacing explosive charges along the haunches for II distance of 50 to 60 feetfrom the entrance, The ehargen should be placed well inside the tunnel lining;they should be well tamped and spaced at Intervuls equal to twice the line o~least resistance.

Uae or ,expl,uMive on switch points}O B lo cks TNT

USe of explostve on f'rogs

Use of exploslv~ on crosalngs

Use of explo"h'c ou ratlroad nilSandbags or dry masonry.

N~RKC"'I0%.R-IS.S', K=.OS76.C-l.N-(13.8)(.087G) (1) + 10'70.N=230 + 23~253 blocks TNT.

FIg. 66.-T.,plcal railroad demolitions

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e. To denlllll,'11 rolling "tuck, the same parts on all locomotives and N:I'Sshould be destroyed 80 that IUII't:-: may not he Inter('illll1;!'tl, To uecompushthe task thoroughly it is a-tvtsabto to (\I'tnil men r I O dp"rror definite parts,

(1) 'l'wo bl{)($2 of triton ,,'iI! br uk a reverse level' or sid? lad.(2) Three blocks wlH brenk :!c c.\'iill(ler;.(3) To break a driver, plnce 3 bhwJ.::':lloh'd l> y upellilll; tb

breech aud setting 11block of 11'ill.lH against the hinge. then partj'llly ('In:;ing thsbreeeh and exploding the chnrg:J. .(2) A 3incb gun lllay be c:ft'e.:tin~ly d{'"tn'y~u liy 1I1acing ii blocks of triton

insid , (1) Tilermlt. a mixture of powdered alurninum und hcmntu e ,2AI+ Ife, l,),may be USE'd for the dloabling of 8!'tillery and in many other eases where t hede~tr""ti()n of m taHie objects is required.

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(2) wnen thermit is ign.lted its temperature rises to 5,000 F., and theoperation is intended to form a lump of steel in the bore or to fuze the breech-block to the gun. The operation is easy ttl perform, and there is lIO dangerof explosion.(3) If the breech gear can not be operated, the gun should be elevated at

about 5 and a wall of day built inside the bore at-nrm's length from themuzzle. A canvas bag containing a mixture of 20.pounds of thennit and 3ounces of carbon dust, into which a spoonful of ignition powder, furnished bythe manufacturer, has been inserted, is placed against this wall of clay. A'"second wall of clay is then built between the charge and the muzzle and againstthe charge. The charge 'is ignited by means of a fuze leading over the outerclay wall. (See fig. H7.) When the molten metal has .cooled to a bright red,water should be thrown on it. The operation requires 'from 5 to 10 minutes,and should result in II lump of high carbon steel meedinto the bore' which dairnot be removed with chisels.(4) If the breech gear is intact, the gun should be elevated, the thermlt

ignited in the powder chamber, and the breech closed. 'I'his wilt result in thebreechblock and the gun being fuzed together.89. Unexploded shells and bombs.-a. Unexploded shrapnel, high explosive

and gas shells, aerial and gas bombs, and grenades found on the field sho~ldbe destroyed under the supervision of an engineer or ordnance' ,..fticer.

b. Ifthe projectile is in a trench or shell hole' where f'ragruents may not heprojected a great distance, it should be destroyed without hnndling ; otherwiseit must be moved to a specially prepared trench which should he at least Iifeet in depth and narrow, so that fragments will be projected vertu-ally ratherthan horizontally. Shells exploded on the ground surface without tnrnping willsend fragments 1,000 yards.c. Shells must be handled carefully. They should be carried 011 improvised.stretchers and jolting must be avoided.

Materlal.-Timber and eartb.Charge: N=R'KC + 25%.R=3'; K=0.1H5 ;C=4.~.N= (3)'(.375) (4.5) + 250/0=45.6 + 11.4.

N=57 blocks TNT.Charge Is supported against root of shelter by struts.FIG. 68.-Destruct!


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be stopped within a radius of 500 yards, find a splinter-proof llhelter at 150yards must be available for the"demolittou party.

SectionMatrilll.-Reinfcr~ed concrete.Charge: N~=R'KC+ 10%; R=W; K=1.(); C=';',5.

N=(3)'( 0 (4.5) + 10%-121.5';' 12.2.N=13i blocks 'I'NT.FIG. 69.-Destructloll o r concrete cover~ & . - 1 ~ W ~ ~

[f~I

Fro. 70.-Destructi(lU of bomb proof.e, Gas shells and bombs should be handled the same as other projectilesexcept that shells of 100 pcnnds should b5 exploded singly. Th!,!gas cloud


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from a shell of this Sl\:'" \ illnot 1~ Qlmg';!rollll at 50!} yru:ds. Holes 01' trenchesIn which gas shells have been f'xjAoded must be Iillet'!,and 'gas masks W01'llduring the work.[, Boxes of nemy explosive must be opened and ~al'afully examined, asdetonntors and hand grenu

hy wire cutters, tauks, artillery fir". and f!xpl;:;sives,b. The iufantry is equipped wiLb wh"c cutters and wi!! normally breach the

belts (j f wire !n tueir attacks. Engineers mt'Y asslst 1n spedi\l condtrtonswhere speeial u lilill.nceg axe required,r, A sif!:;ie line 1)1' ctrain of trtton blocks nlll.~ed end to end and touchtng,

fl tonrtte(! at ti Sing!!,' point, nas clp8.n ..... 31lP~ 10 ytll'ds wide ill double apron, :\. ' reo The cnaln should l,p plnct:;d besiolt' 11:1.111ot between pickets.92. It!l.ngalore tOl"pedoes.--tl .. A Baugalore torpedo consists of Ii section of

pipe 01 " other "lmiifu ""sIng fillPtI wlth D. h:gl! explosive, Due to its ';Velght,shape, and !.h~ car e n=cessarv in asscmbltng, it 1 . ' 1 difficult to carry long dis-ranees 01"o..er broken grolL'ld. and tho results froID its use are not certain.

'Il. The torpedo is 'J$.nnHy made np in three 1(1-foot seettons consistlng of aleading eml, it canter section, ano:! e . tr;,iJing end. 'rhe leading- end is fittedwith t rounded 'ltlodeli 11;1;0to prevent it froUl being eaugnt in the wire ormaking a s"Ia!.,hip.g norse. Tbe tfll.ilin;::cud is fitted with il wooden plug anda greased paper sleeve hlrol'gh whkll (h. riming fuze is inserted. The cen-ter pit'ce is joined to til;; t>nd.pif!c{ls by male and i't'IDnle jOints. The sectionsan' tlllE'd wlth Ti'-:T blecks plaeed oud to end, Provislon must he made to(,[lrn' the detonatlon [last the joints by deton:lt!u!!: cord, or by Induced detona-tion (soc par. uti), Each sectlon is carrted forward separately 1 1 nd assemblednCJll" the "It .

< '. Aftel" assetnbhng rotth' site, th torpedo should he-pushed forward Oil theground nude the belt (.f wire wbel";" tire l-reaeh ts desired.d. The Bangutore torpedo p8.rtj' sonuhi em'.'~lst of 8 men. Two men carry

etlch seetton ",['(1 the remalnlng 2 men carry c;x:ra ooden 110;;('8, firing de-l"lC'?~~.etc.e. Dt'tolltltion by saiety fuze is recommended as the t.e.i't method, The ~9fetyfuze should lie eut ,1 bur abont 1:; seconds. As an R.dditional precaution, autnstuutaueous fnze prtruer should be pro"irled. 11the time fuze fail" to deto-Illite the cap, t is tnstnntaueous fuze can be used.


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THE USE OF EXPLOSIVES IN' ENGINEERIXGS~CTroN X

ParagraphG e u c r n l . . . D ~Road and railrQad bulId1Dg .. .. D4D j g ~ i u g - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4 - - - - - ~ ~ ~Dll:ging trenches wLth vertical wuIls .._.. a l iScrapping heavy muchlnery and blasting old foundat io l l "_________________________ !l7Ice gorges . ~ ~ .__ 08Stump blastiuu .... -. . !lllDltrating bowtdcr . .... . 100Blusttng ' welts ...... . .. . ..__ ______ ____ 101flitchlng und druluuge .. .. .. . . 10:!Otber u~es 10393. General.-The mtlitnry eugineer is confronted with many UlK1 v ried

construction projects. Often in these projects the use of exptosivcs will boiruperative, and stUl more often tbelr use will facilitate the progress of tilework Hence brief descrtprlons of 3. few such uses are included hnrr-iu.These descriptions are not intended as hard and fast methods but merelv to8N'Ye as guides. As the officer becomes more and more familinr with theuse of explosives, various methods wltl suggest themselves. Every demol i-tion project shonld be studieu both [01' improvements ill tbe manner of usingthe explosive ,and as to Its bearing on future '....ork.94. Road and raflroad buUding.-a. Uxpluslves are useu in road aud ra il-

1'011(1 bullding for the following purposes :(1) Removing stumps aud bowlders.(2) Opening ditches.(,3) Opening verttcal drain II.(4) Looseniug bard gl'onnd in gvadlng.(5) Blasting rock ill grading.

FIG.71.-Locatton of verti~a! hore holeIn road cut F10.72.-T~c"tj"n or hrolizontal 0r fiatbore hole , II I rood u t ( j l ' Blasting for surtactnz and ballasting materials. gtulllP and bowlder

blasting p.r~ tlt!scribed in paragrnpds un and 100, respectively.t. (l) Ha"'. clay or rock in 'cuts muv be loosened hy btust ing with ('hnr).:'5leaded li7 hortaontal 01: vertical boles. The selection of the direction of tbp holesruust h~.govern'ed by the uuturs of the ground, Where tho ground bas horizon-tn) sea . the vertical hole (fig. 71) is prefernble : witu verttcal SE;':Ll l1S orwhere tp e grouud is hardest at the top the flat hole (fig. 72) is p"cfemhle.

(2.) \yith vort ical holE'S, drill a line ., f holes all the way across the cnr to artepth of about 1 foot below grade and spaced from three-fourths to four-ttf'tlisof thelr deptn up to 6 fee!, Above 6 feet, spacings should be from oue-nalf \0


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Fm, 73.-PIll.ll of apprcatmate loading' tor cuI work

FIG. 74.--Elevll HODotapproxlmate loadiug for cut work

FIG. 75.-E!~avated material to be hauled ,,)s('whHe


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three-fourths of the depth. The burden (A in. llg.''l'::h should be sl1ghtly greaterthan tbe spacing between holes (B).

Flo. 77.-Loadlng to blast ashalloW' post bole Fro. '1S.-Loodiilg IIdeep bole

(3) AU holes should be sprung before final loadiug. '!'he amount ot thecba.rge should be determined by experiment.

c. There are two methods of making sldebill cuts. In one method (fig. 75)all of the ground is excavated and the roadbed is 011 soltd ground. In tbeother (fig. 76) the cut is not 8S wide and the 8poi1'18 )Jsed as 1I.1llng.

o o--. _ . -----------------Plan

FlO. 79.-Dlgg1ug II trenell

4. Explosives may also be used to advantage in Ioosenlng soU for roadmachInes or hand digging or to speed up steam-shovel excavation. They may.also be used for side ditching, etc.95. D{gging.,-TritQn and dynamite are both useful for digging holes fortelephone and other poles. To blast post holes In earth, flrstremove the sur-tace to depth of from 6 to 8 inches or down to the hard ground and 1 '0 thet a u diameter of the desired hole .. Then prepare IIbore bole lind load as shown


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ln INgures 77 and 78. In rock the bore hole must be chambered before .linalftrin~ .00. Digging .trenchflSwith vertie&l ",."Il.B.-Figure 79 snows a method for

digging trenches with vertical wall& Tbe holes Indicated A should be 1l.redtogether, Qnd tbe ['emain1ng boles In the order Indicated ulphabetleally.

9"1 ' . Sempping .heavy machinery and blasting old foundations.-E;t:ploslvesare often used In eonstructlon work tor sett.pping heavy machinery and forblasting old masonry or concrete, Methods Involved are !fully described Inseettons Val and IX.

' < i 1 m p i n g'/ec.8/dJi Cap'Carlniige

FIo. 81.-Loadlllg a tap-rooted stump fO Tan electric bias'FIG. 80.-LondIDg II. tap-tooted!JtUm"p wit4 a Bingle .cba~98. Ice gorgeg.~. Ice gorges clloldng up running streams andthreatf!!lling

bridges. dams, and other structures may be blasted by boring and loading boreholes or by mud eapplng,

T o EI~c""icBlasling Mad7ine

FIG. 82.-Loadl:l!l" lateral-rooted stumps(1) In th first method holes should he 'Jut through t.he tee at frequent

intervals and the charges. tied to blocks of wood, thrust through tJie holesand allowed to float under the ice II uttle way from the holes. Such blastsraise the ice and then break it apart.(2) III tbe second method large charges are loaded on the ice at frequent

intervals and ftrM.I), Defh.ite amounts of explosives to be used in ice blas ring can not be given

hut must be determined by test charges. In general. ice 3 01'4 feet thick winrequire charges of about 15 pounds of triton.9S. Stump blastlng.-a. StUIIJP blasting varies with the clusses or stumps

and soils Involved. Some stumps have heavy tap-roots; others have onlylatera], spreading roots, while still others have both. GreE'11stumps are

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harder to blast than df-Iu) ones. Stumps In firm soil are more ea'lily btastedthan stumps in IGo~. sandy "oil.h. Figure 80 shows a method of placing charges for blasting tap-rooted

stumps. Figure 81 shows nnothr-r method In whteh the holes are bored into

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-,;. Snakeholing consists of placing a bole under and immediately agalDstthe bottom of a bowlder, charging and tamping the hole. (Fig. ~.)c. Mudcapping is known by a. variety of names: Bulldozing, blistering, l)Qtd ..

. ticiing, and adobe shooting. It is made possible by the sbattering action of bigb

FIG. &S.-Completlng the excavationexplosives. Figure 86 shows a method of mudcapplng.Tbe explosive shouldbe placed on the bowlder at the place where the rock would be struck to breakitwith a hammer. When the bowlder is.embedded in the ground, a .snake boleshould tkstbe made toroH itout on the surface, as the confining dirt makesthe bowlder much harder to break with !II mudcap shot.

FIG. 8U.-Propagated ditch blast. Charge!! fired by induced detonation101. Blasting wells.--a. Explosives can be used to advantage in sinking

wells through rock or ground which can not otherwise be dug to advantage.Figure 87 shows the first shot, and Figure 88 the excavation shot.

Proposal$ra..d~ ofdttcb.J :Pr imed dynam.\tc: ca.t'tTidSt"SFIll. '90.-EllectrlcaUy fired dItch blast

b. Often the supply. of water from drilled wells can be Increased 'by blasting.Such blasting endangers. the water supply' already present, however, and the

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advice of a goo!og13t should fi.M be ' 9~. The well is blasted by setting ofta charge :!:ntl!.e bottom~102. pttclWlg and .dra!nap.~. DItch blastlng Is e1!ect1ve in all classes of

grQulld, !rom ioijd rock to loam. but IIJ110t e1r.ective tn_loOse' sand or gravel.There are two methods of dJtch blaatlng, the prQpago,tiOJt metllod and the e'ectricV i 'W '& 1 w d . .(1) In the proJldgntlGIl method cbarges are Ioaded and tired as shown. in

Figure 89. The size ot"hole andlimonnt of e:tpios!ve required are detennilloo.by first blafttlng a tew test holes. Wben 40 per rent and 60 per cent dyn!UDite: S s used caps are 110t required,eJ:oopt tor the initial charge..(2) Figure 00 shows the loading for the electr!cal method.b. Flgw'e 91 Ulustrates a blasted drainage bole providing vertical dl"l:Ilnage

wbt>.l'ed1tcheddm~ til impra.cticable.

11'19.91.-Bhl8tE'd dm iTlage bQle103. OthEr wteII.-E%ploslves-may be used to great advantage in quarrying,twme11ng, submal'ln'! blaBting, etc. Such work 1.8complicated. lind the services

of an expedeb.:li!d blutet are required in order. to secure the best results.

TR 195-30 Explosives and Demolitions

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Transcript of TR 195-30 Explosives and Demolitions