Blasting Design
ROCK Breaking MECHANISM
1. The process of solving Tk I (Dynamic Loading)
When the rhino explodes, high P destroys the rock around the blast hole. The shock wave propagates at a rate of 3000-5000 m / s resulting in tangential stresses that cause fractures that radiate from the explosion hole. Fracture of finger I occurs in 1-2 ms
2. Tk II Solving Process (Quasi-static loading)
with respect to the shock wave leaving the blast hole in process I is +. When it reaches the plane of the beam it is reflected, the pressure drops rapidly, then changes to – and a tensile wave occurs. The wave of attraction travels back to the rock. Because rocks are less resistant to tension than pressure, primary fractures will occur due to the tensile stress of the reflected waves. If the tensile stress is strong enough it will cause slabbing / spalling in the free plane. Process I and II are a function of the shock wave energy: preparing the rock with a number of small fractures for the final breaking process.
3. Tk III (Release of Loading) Breaking Process
Under the high pressure of the blasting gases the primary radial fracture (TkII) is rapidly expanded by the combination of the effects of tensile stress due to radial compression and splitting. If the mass of the rock in front of the blast hole fails to maintain its position to move forward, the high compressive stress in the rock will be released like a spiral of pressed wire and then released. The effect of the loose rock causes high tensile stress in the rock mass which will continue to break the results that have occurred in the Tk II breaking process. The fracture resulting in Tk II cracking causes a weak field to initiate major fragmentation reactions in the blasting process.
3.2. EXPLOSION DESIGN
– Blasting geometry
– Drilling and blasting patterns
– rhino necessities and equipment
-production blasting
-Post production handling
3.2.1. Uncontrollable Design Factors
-Geology: rock type, rock mineral type, rock weathering process
Weathering Factor:
Mineral components, climatological factors, grain size / min, rock porosity and permeability, relationship / contact between rocks, rock dissolving properties
-The nature of rock strength
– Rock Discontinuity
– Weather conditions
-Water effect
3.2.2. Controllable design factor
1. Drilling Geometry
-Diameter of blast hole, depth of blast hole, inclination of blast hole, level height, drilling pattern
2. Blasting geometry
-Burden, spacing, Fill length, Subdriling, steaming, blasting pattern, delay timing, ignition sequence
3. Rhino and Accessories
-Type & strength of rhino, detonator, etc.
I. Geometry of Drilling
a. Blast Hole Diameter:
The determination of the diameter depends on:
-Volume of rock mass to be dismantled
-level height and input configuration
-tk the desired fragmentation
– Drilling machines available
-capacity of the loaders that will handle blasting material
Small Explosive Lub Diameter:
-only for ta / quarry with small product volume
-krn B n S meeting then the number of blast holes>
-High drilling and booming costs
Advantages of Big Explosion Hole Diameter (5 inch />):
-Fill diameter> so that the det> speed is high
-Drilling productivity> high
-Mechanical filling system
-Relatively low drilling and blasting costs
-The productivity of the loading tool can be increased due to the productive work area
b. Explosion Hole Depth
Adjusted to the height of the level. The depth of the blast hole must be> than the cascade height.
c. Burst Hole Inclination
Can be upright / tilted. The direction of alignment of the boreholes in the ladder should be parallel to ensure burden and spacing absorption in the blasting geometry.
Advantages of upright blast holes:
-for the same level height, the length of the blast hole is shorter than the inclined blast hole
-Less likelihood of throwing rocks
-easier to work with
Loss:
-The crushing along the blast hole is uneven
-> produce lumps in the stemming area
-Creating bulges on the floor level
-Create backward cracks with ground vibrations.
d. Drilling Pattern
-Pattern parallel drilling (parallel):
pattern by placing the explosive holes in a sequence and parallel to the burden
-Staggered drilling pattern
the exploding hole alternating drilling pattern is located in a sequence which is not parallel.
2. Blasting geometry
A. Blasting Geometry C.J. KONYA
1.Burden:
the shortest perpendicular distance between the rhino’s load and the closest free plane / direction to which the bat will be thrown.
B = 3.15 De (Sge / SGr) 0.33
B = [(2Sge / SGr + 1,5)] De
B = 0.67 De (Stv / SGr) 0.33
B: burden (ft)
De: Diameter of explosion (inch)
SGe: SG rhino
Stv: relative bulk strength (ANFO = 100)
Be = Kr x Kd x Ks x B
Kd: factor to lap bat position
Cr: factor thd number of lubricants
Ks: factor of geological structure
2.Spacing, S
The distance between the hole in 1 gram which is parallel to the free bid.
S = (L + 7B) / 8
S: spacing(m), L: level height, B: burden
3.Stemming, T
The column covering the lub ldk on top of the rhino stuffing column
T = 0.45 x De x (Stv / SGr) to the power of 0.33 (Ft)
4.Subdrilling, J
Mr pjg lub ldk which is below the level floor which serves to make the tier floor relatively flat after blasting.
J = 0.3 B (m)
5. Time Delay
To get the difference in play time between 2 holes, it is not possible to obtain it in a row.
Tr = Tr x B
Tr: time delay between brs lub ldk (ms)
Tr: delay time constant
6. The use of rhinos
To determine the number of rhinos used in each hole, the loading density is not determined.
de = 0.34 x SGe x De squared
de: loading density (lb / ft)
Determine the number of rhinos per hole:
E = Pc x de x N
E: number of rhinos
Pc: height of stuffing column (m)
de: loading density (kg / m)
N: number of lub ldk
B. Blasting Geometry R.L. ASH
DISPARATION FEES
Total drilling costs with blasting costs.
Blasting Fee:
1. The cost of primary + explosives
2. Equipment costs:
-Detonator, Sb Explosion, Sb Api, Nonel, M-S Delay
3. Depression Tool: Exploder
4. Operators (explosives) N Assistants
TUNNELING
SEWDISH METHOD
Nomenclature
CUT HOLE – parallel hole cut
V CUT
Functions:
Cut Hole: blown to make a free hole
Cut Spreader hole: widens the free field
Stopping hole: blasting the center of the opening hole section
Roof hole: blasting the roof
Wall hole: detonates left and right
Floor Hole: blow up the floor
Blasting Drilling Patterns in Tunnels
5. CONTROLLED EXPLOSION
The blasting technique used / the drilling and blasting pattern is arranged in such a way as to regulate the overbreak and to regulate the stability of the rock formation that is left behind (can be in the form of rock)
Controlled Blasting Method:
A. Line Drilling
Aims to create a weak plane through which rock can be dismantled. Aligned boreholes help reflect further waves, reducing the crushing effect of rock beyond the demolition boundary
B. Cushion Blasting
The blasting method is similar to line drilling, the diameter is 51-89 mm, the difference: in custhon blasting, the tight holes are filled with a little rhino and are well distributed, after being filled they are clogged with soil, then compacted, and are blown up after the production hole is blown.
Advantages:
-The number of drill holes is needed a little
-On rock nitrogen application of CB is better The result (Bat obtained is better)
Loss:
– expensive because you have to move the blasting product
-Production delay due to excavation for the entire area can not be done at once
C. Smooth Blasting
Most famous and applied to tunneling (making tunnels by means of blasting) and the most recent blasting.
Difference between SB and CB:
-In SB the stemming holes are at the top but not the whole part of the hole, so that there is a hole filled with air.
-SB, the contents are below
D. Presplitting
In a large hole filled with rhinos, the hoe complete is blown first so that a fracture occurs
If the part above is detonated there will be a shock wave. The shock waves that arise will be reflected so as not to disturb the surrounding buildings
source: http://alibie-analyzer.blogspot.com
