Blasting Materi
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BLASTING 1) Fre e fac e make the roc k moves fre ely beca use crea ted new free spa ce. Rock movement direction tends to slide into the free face. Therefore, if there is only have one free face, so the rock tend to fly to u pward or called as flying rock. 2) Bur den is the dist ance betwee n free face wit h shot hole. If the free fac e too closes with borehole, it will be happened flying rock, because the energy is too huge. If the free face too far from borehole, so the blasting result is not good enough. 3) Stemming is the col umn in the boreh ole that filled by non-explos ive subst ances (st ones or cutting from borehole). The size of stemming column determines the result of blasting. If stemmi ng col umn too sho rt, the n ver tic al ene rgy and explosive ene rgy that wil l be happened too huge, therefore will create flying rock and indicated with concave dome at material blasting. 4) In blast ing method , stif fness r atio that proposed not exc eed then 1, 25. Stif fness ratio is a comparation between the size of “jenjang (bench)” with the size of burden. Its mean size of “jenjang” have to bigger ¼ time than burden size in order to make good blasting results. 5) In del ay i nstal latio n, we have t o conce rn abo ut t he prec isio n. If we hav e long burden then installed fast delay, then it will be occurred heavy load for next process blasting, because the first blasting isn’t finish yet then continued with next blasting, because not create free face yet. Blasting Theory Rock rupturing process at blasting From ini tia tion point (titik pembakaran), explos ive mater ial break shot hole wall, thi s happened because of huge pressure around blasting area.
Transcript of Blasting Materi
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BLASTING
1) Free face make the rock moves freely because created new free space. Rock movement
direction tends to slide into the free face. Therefore, if there is only have one free face, so
the rock tend to fly to upward or called as flying rock.
2) Burden is the distance between free face with shot hole. If the free face too closes with
borehole, it will be happened flying rock, because the energy is too huge. If the free face
too far from borehole, so the blasting result is not good enough.
3) Stemming is the column in the borehole that filled by non-explosive substances (stones or
cutting from borehole). The size of stemming column determines the result of blasting. If
stemming column too short, then vertical energy and explosive energy that will be
happened too huge, therefore will create flying rock and indicated with concave dome at
material blasting.
4) In blasting method, stiffness ratio that proposed not exceed then 1, 25. Stiffness ratio is a
comparation between the size of “jenjang (bench)” with the size of burden. Its mean size of
“jenjang” have to bigger ¼ time than burden size in order to make good blasting results.
5) In delay installation, we have to concern about the precision. If we have long burden then
installed fast delay, then it will be occurred heavy load for next process blasting, because
the first blasting isn’t finish yet then continued with next blasting, because not create freeface yet.
Blasting Theory
Rock rupturing process at blasting
From initiation point (titik pembakaran), explosive material break shot hole wall, this
happened because of huge pressure around blasting area.
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Compressive stress spread to all direction with the equal velocity and sonic wave velocity,
when this compressive stress pass through free face and bounce back, therefore create tension
force when rock tension force exceeded and the rock will rupture.
When produced fracture because of rock rupture, gas expansion from blasting material pull the
rock to all direction.
The quality of borehole can be looked from:
Sequence of boreholes
Direction deviation and the angle of bore
Depth and purity of borehole
There are 2 drilling pattern;
Rectangular pattern
Staggered pattern
Free Face
Pola pemboran square, pola peledakan V-
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Initiation
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If burden too tight, then the rock will not be deformed perfectly and explosive energy throwed
as ground vibration.
Bila “Burden” terlalu tebal maka tidak terjadi deformasi batuan yang sempurna dan pada
keadaan ini energi bahan peledak akan terbuang berupa getaran (ground vibration).
Sebaliknya, bila “Burden” terlalu tipis maka sebagian besar energi bahan peledak akan
terbuang sebagai suara (Noise) dan air blast. Untuk itu harus dicari / ditentukan jarak burden
sedemikian rupa sehingga energi bahan peledak terpakai untuk menghancurkan (men
“deformasi”) batuan.
Delay relayconnector (DRC)
Free face
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2 3
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