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Schedule
No Subject Week References
1 Tujuan Peledakan 1 1
2 Pengenalan Bahan Peledak 2 1, 2, 3, 4
3 Karakteristik Bahan Peledak 3 1, 2, 3, 4
4 Interaksi Bahan Peledak & Batuan 4 1, 2, 5
5 Energi Peledakan 5 1, 2, 5, 6
6 Teknik Pengeboran 6 2, 8
7 Peledakan Tambang Terbuka 7-8 1, 5, 6
8 UTS 9
9 Peledakan Bawah Tanah 10-11 1, 2
10 Dampak Negatif Peledakan 12-13 1, 2, 5, 6, 7
11 Teknik Peledakan Terkontrol 14 1, 2, 6
12 Peraturan Operasi Peledakan 15 KepMen, SNI
6. Rancangan Peledakan
Jenjang
Ganda M. Simangunsong
Fakultas Teknik Pertambangan & Perminyakan ITB
Terminologi Peledakan Jenjang
4
Variabel Rancangan
▪ Pola pemboran
▪ Pemuatan
▪ Penyalaan
Peledakan Jenjang
5
6
Bidang Bebas (Free Face)
Three Free Faces
1
32
Two Free Faces
1
2
One Free Face
1
7
Kualitas Bidang Bebas
Pemilihan Diameter
Terlalu besar
▪ Distribusi energi dan Fragmentasi
▪ Batasan lingkungan
▪ Kerusakan batuan
Terlalu kecil
▪ Diameter kritis
▪ Biaya pemboran
▪ Target produksi
Adhikari, 1999
PemilihanDiameter
Hole diameter selection
While selecting the proper blasthole diameter, the average production per hour, or excavation, must be taken into account (Table 4). In addition, the type of material excavated must also be accounted. An important aspect when drilling is the drilling cost. The cost usually goes down as the diameter of the hole increases.
Hole diameter selection
Much of the same criteria for drilling parameters are the same for large diameter blasts as they are for small diameter blasts. The average production per hour and type of rock being fragmented is still the variables needed for consideration (Table 8)
12
Penentuan Burden (B)
Fly rock &throw
Less Burden
Cratering &
Fly rock
Poor Fragmentation
Excessive BurdenOptimum Burden
Contoh R.L. Ash
▪ Batuan standar - Bobot Isi 160 lb/ft3 (average rock).
▪ Bahan peledak standar - Berat Jenis (SG) = 1.2 & VOD (Ve) = 12.000 fps.
▪ KBstd = 30.
▪ Apabila peledakan dilakukan pada batuan yang bukan standar
dengan menggunakan bahan peledak yang bukan standar, maka
perlu dilakukan pengaturan kembali harga KB (nisbah burden yang
telah dikoreksi)
▪ KB = KBstd x AF1 x AF2
3
1
2
2BPBP
3
1
[12000] x 1.2
][VOD x
standar peledak bahan potensial Energi
dipakai yangpeledak bahan potensial EnergiAF1
=
=
3
1
Batuan
3
1
pcf 160
diledakkan ygbatuan Isi Bobot
standar batuan Isi BobotAF2
=
=
Penentuan Kb Empirik
▪ Light explosives in dense rocks KB = 20
▪ Heavy explosives in light rocks KB = 40
▪ Light explosives in average rocks KB = 25
▪ Heavy explosives in average rocks KB = 35
▪ B = Burden (ft)
▪ De = Diameter lubang tembak (inci)
KB = 12 [B/De]
Burden Determination
Anderson [1] developed the following empirical equation:
where:
▪ B = burden (m)
▪ K = a proportionality constant (1-6)
▪ Dh = blasthole diameter (mm)
▪ H = bench height (m)
▪ In the above equation, for a good fragmentation: H/B 4.
Burden Determination
Fraenkel [2] suggested the following more sophisticated equation:
where:
▪ K = experimental constant (between 1 to 6 for most rock types)
▪ h = length of the Charge in the blasthole (m).
Burden Determination
Lambooy and Jones [3] expressed the following formula for determination of burden:
where:
▪ S = spacing between the blastholes (m)
▪ We = weight of explosive in kg/m run in a blasthole
▪ q = weight of explosive to break unit volume of rock (kg/m3)
Burden Determination
Pearse (1955)
▪ Where,
▪ B = maximum burden (m)
▪ K = Constant, value varies from 0.7-1.0
▪ Ps = Detonation pressure of the explosives (Kg/cm2)
▪ σt = Tensile strength (Kg/cm2)
▪ d = Diameter of borehole
Burden Determination
The equation for maximum burden value proposed by Allsman (1960) is;
Where,
▪ PD= Mean adverse detonating Pressure, N/m2
▪ t= Duration of average detonation, sec
▪ ρ= Specific rock weight, N/m3
▪ u= minimum velocity which must be imparted to the rock, m/s
▪ g= acceleration due to gravity=9.81 m/s2
▪ D= Diameter of blasthole, m
Burden Determination
Langefors and Kihlstrom (1968)
Where,
▪ Bmax = Maximum burden for good fragmentation (m)
▪ D = diameter of hole (m)
▪ ρe =Density of the explosive in the borehole (Kg/m3)
▪ PRP = Relative Weight strength of the explosive
▪ f = Degree of confinement of the blasthole.
▪ S/B = Spacing to burden ratio
▪ Co = Corrected blastability factor (Kg/m3)
= C + 0.75 for B max =l.4-1.5m
= C + 0.07/B for B max < 1.4m
When C = rock constant (0.4 for average rock for first trial)
Burden Determination
Lopez Jimeno, E (1980) modifies the ash’s formula by incorporating the seismic velocity to the rock mass, resulting in
Where,
▪ B= Burden, m
▪ D= Diameter of blasthole, inches
▪ F= correction factor based on rock group = Fr× Fe
Lopez Jimeno, E (1980) cont.
Where,
▪ ρ'= specific gravity of rock, gm/cm3
▪ VC= seismic propagation velocity of the rock mass
▪ ρ''= specific gravity of explosive charge, gm/cm3
▪ VD= Detonation velocity of explosive, m/s
Burden Determination
Konya and Walter (1990)
Where,
▪ B = Burden, (ft)
▪ ρe = Specific gravity of explosive, (lb/in3)
▪ ρr = Specific gravity of rock, (lb/in3)
▪ D = Diameter of explosive, (in)
Konya & Walter (1990) cont.
Correction factor, Bc = Kd. Ks. Kr. B
Where, Bc = Corrected burden (ft);
Kd = Correction factor for rock deposition. Its value is as follows,
• for bedding steeply dipping into cut Kd = 1. 18
• for bedding steeply dipping into face Kd = 0.95
• for other cases Kd = 1.0
Ks = Correction factor for geologic structure. Its value is as follows,
• for thin well cemented layers with tight joints Ks=1.1
• for massive intact rock Ks = 0.95
Kr = correction factors for number of row. Its value is a follows,
• for one or two rows of blastholes Kr = 1.0
• for third or subsequent rows Kr = 0.95
Burden Determination
Konya and Walter also suggested the following empirical relationship-
Where,
▪ S ANFO = relative strength of explosive
▪ ρr = density of rock, gm/c.c.
▪ d = diameter of blast-hole, m
Burden Determination
Russians suggested [10] a variety of equations to relate burden and blasthole diameter. Amongst the most predominantly used are the ones as follows:
Russians cont.
where:
▪ 2x = length of the charge in the blasthole (m)
▪ r = radius of the fractured zone in rock (m)
▪ fp charge packing factor (see Table 1)
▪ d = decoupling = Dh/D e.
Burden Determination
Afrouz [11] presented an empirical formula to determine the burden in terms of a single impact force to cause rupture (F) and the dynamic tensile strength of rock (td) as follows:
where:
▪ n = a constant related to the effect of rate of explosion on the braking properties of the rock = 1.04 for limestone, and 1.39 for concrete.
▪ c = constant related to the type of loading, for direct impact it was evaluated to be 4.07.
Burden Determination
Hino [12] based on the propagation of the shock waves and its reflection at a free face suggested the following equation:
where:
▪ n = a constant = 1.5, on average,
▪ Pd = detonation pressure (MPa)
Mishra (2009)
A relationship between burden with blast hole diameter
Contoh Variasi Penentuan Burden
31
Pengaruh Kekar Pada Peledakan
(Dyno Nobel, 1995)
A
Orientasi bidang diskontinuitas ke arah pit :
- Ketidakmantapan lereng
- Backbreak berlebih
Orientasi bidang diskontinuitas ke arah
massa batuan :
- Toe tidak hancur
- Potensi batuan menggantung
B
Orientasi bidang diskontinuitas sejajar
bidang bebas :
- Lereng mantap
- Arah lemparan terkontrol
Orientasi bidang diskontinuitas menyudut
terhadap bidang bebas :
- Muka jenjang berblok-blok
- Hancuran berlebihCD
Pengaruh Struktur Pada Peledakan
Koreksi Geologi Untuk Burden
Koreksi Deposisi Batuan Kd
Bidang perlapisan curam agak miring menuju bukaan 1,18
Bidang perlapisan sedikit curam mendalam ke arah dalam 0,95
Kasus deposisi lainnya 1,00
Koreksi Struktur Geologi Ksg
Batuan banyak terekahkan, banyak bidang lemah, tingkat
sementasi lapisan lemah1,30
Lapisan batuan dengan tingkat sementasi kuat dan tipis dengan
rekahan halus 1,10
Batuan masif utuh 0,95
B’ = Kd x Ksg x B
Penentuan Spasi (S)
Sistem penyalaan Stiffness ratio L/B < 4 Stiffness ratio L/B 4
Serentak S = ( L + 2B )/3 S = 2B
Tunda S = ( L + 7B )/8 S = 1,4B
Waktu tunda Ks
Long interval delay 1
Short period delay 1 – 2
Normal 1,2 – 1,8
Penentuan Spasi Menurut RL Ash
Penentuan Spasi Menurut Konya
Pemilihan pola Spasi
Square pattern
Burden = spasinya. Posisi lubang tembak pada baris berikutnya berada tepat
sejajar di belakang lubang tembak pada baris di depannya.
Rectangular pattern
Spasi > burden. Dalam penerapannya di lapangan, pola ini memiliki jarak spasi
maksimal sebesar dua kali jarak burden.
Staggered Pattern
Posisi lubang tembak pada baris berikutnya berada di tengah spasi baris di
depannya. Keuntungan menghasilkan distribusi energi peledakan lebih baik &
cenderung memberikan keseragaman fragmentasi.
Penentuan Tinggi Jenjang (H)
▪ H > burden untuk menghindari terjadinya overbreak.
▪ Kh = H/B
▪ Kh = 1,5 – 4,0 (Burden Stiffness)
B H
Burden Stiffness > 2
B H
Burden Stiffness < 2• Difficult to break
Pengaruh Burden Stiffness(Konya, 1990)
Burden Stifness
(H/B)Fragmentasi Air Blast Fly Rock
Vibrasitanah
Keterangan
1 Buruk Berpotensi Berpotensi Berpotensi
Potensi terjadinyaback break dan toe.
Harus dihindari dandirancang ulang
2 Sedang Sedang Sedang SedangSebaiknya dirancang
ulang
3 Baik Baik Baik BaikTerkontrol dan
fragmentasi memuaskan
4 Sangat baikSangat
baikSangat
baikSangat
baik
Tidak menambahkeuntungan bila
stifness ratio dinaikkan lebih dari 4
Pengukuran Kedalaman
41
Penentuan Subdrilling (J)
▪ Lubang tembak yang dibor sampai melebihi batas lantai