This document provides information about drilling and blasting techniques used at Suez Cement quarries. It discusses drilling methods, including rotary and rotary percussion drilling. It also covers topics like blast hole patterns, burden calculations, deviation control, and factors that affect drilling and blasting performance. The document then discusses explosive types like ANFO, emulsion, and dynamite used in quarry blasting and compares their properties.
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Drilling Types
Rotary Type by using:
- Tricone bit (water & oil).
- Drag bit (core drilling).
Rotary & Percussion Type by using:
- Top Hammer (drifter.) < 20m.
- Down The Hole (DTH) > 15m.
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Advantages of Drifter & DTH
Down The Hole (DTH)Top Hammer (drifter.)
Short holes: constant.Short holes: very fast.
Long holes: very fast.Long holes: very slow.
Straight drilling in Long holesHighly deviated in Long holes
Soft – medium hard rocks.Hard rocks.
More complicated.Very simple to use.
Cost effective in long holes.Cost effective in short holes.
Hole diameters (4.0 -12.0 in)Hole diameters (1.5 – 4.5 in).
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Down The Hole (DTH)Top Hammer (drifter.)
1 - 2 Tube: 2.5 min.1 - 2 Tube: 0.5 min.
3 - 4 Tube: 2.5 min.3 - 4 Tube: 1.5 min.
5 - 6 Tube: 2.5 min.5 - 6 Tube: 5.0 min.
7 - 8 Tube: 2.5min.7 - 8 Tube: 15 min.
9 -10 Tube: 2.5 min.9 -10 Tube: 35 min.
Drilling time (30m) = 25 min.Drilling time (30m) = 1:54 h.
Av. Drilling time = 50 sec/m.Av. Drilling rate = 3.8 min/m.
Drilling Rate
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Practical rule of burden: V = d
Burden (V ) in meters.
Hole diameter (d) in inch.
Burden
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Burden: is the closes distance to the free face when the blast hole
detonates. It has to match (1) Blastability of the rock. (2) Energy of
the explosive. (3) Delay between the rows or vice versa.
In case the burden is too big:
The energy and burden velocity will be to small. This will not create
enough space in front of the next row, for it to swell. These will
causing vibration, fly rock and air blast. The muck pile will have a
high profile and compact, it will be well fragmented, but with boulders.
In case the burden is too small:
If the burden is to small the energy will be to big with a high
probability for face bursting and fly rock. Burden velocity may be to
high. The front row may move to far and not shield from fly rock from
the next row resulting in fly rock and air blast. The muck pile profile
will be very low, covering a big area and poorly fragmented.
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Spacing (Span): is a function of burden and the break out angel
of the holes.
In case the spacing is too large:
If the spacing is to large the rock between the holes is poorly
fragmented, and often creates Delta shape. This problem will
increase the burden of the next row, with a probability for air blast,
fly rock and back break.
In case the spacing is too small:
The energy overlap between holes will be to large with a probability
of face bursting, fly rock and air blast. Some times the hole
damages the adjacent holes during its initiation.
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The break out angel is typically 90º to 160º and will
increase by decreasing burden.
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EV
Burden/Spacing Ratio
Rule of thumb 1
Vmax in meters = hole diameter in inches.
Then reduce Vmax for inaccurate
drilling and rock proporties.
Rule of thumb 2
The spacing should be
approxemetly (from 25% to
60%) larger than the
burden.
E = (1.25 - 1.6) x V
V/E ratio: 0.6 – 0.8
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Sub drilling = 30% of Burden (U = 0,3xVmax)
Hole Depth
V
U
K
Hole depth= (K+U) / cos α
α
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• Less benches to construct and maintain
• Less sub drilling
• Less boulders
Bench Height
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• Better hole accuracy
• Higher penetration rate over
the hole depth
• Maximised burden/spacing
Less benches to
construct and maintain
Less sub drilling
Less boulders
Bench Height
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+ Reduced drilling and
explosive costs due to
increased burden
+ More stable bench edge
+ Less risk for back break
– Increased risk of hole
deviation
Inclination of Drilling Holes
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Calculation of Drilling Angle
V
K
α
L
Drilling Angle = (α)
(L / K) = tan (α)
(α) = tan-1 (L / K)
Ideal blasting angle: 45o
Ideal drilling angle: Vertical.
Ideal drilling & blasting angle: 18o
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The burden in the front of the holes does deviate from
the planned:
Burden of Front Row
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Incident / Consequence:
1) Face burst.
2) Fly rock.
3) Air blast.
4) Vibrations.
Caused by:
1) Back break from the previous blast.
2) Bad blast direction.
3) Jointing and faulting.
How to Detect:
1) Face burden scanning using laser profiler.
2) Drill hole deviation equipment.
3) Manuel inspection of the face.
Burden of Front Row
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Action:
1) Reduce back break by a improving the blasting
direction.
2) Optimise energy and timing.
3) Optimise bench shape and reduce bench stiffness.
4) Reduce edge effects.
5) Reduce fly rock potential by matching the energy to
the actual burden in front of the hole using air deck,
stemming deck.
6) Drilling of extra holes.
7) Backfill of sand.
8) Blasting mats.
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Drill-Hole Deviation
Incident / Consequence:
1) Risk of face burst.
2) Fly rock and air blast.
3) Vibrations.
4) Risk of flashover initiation between shot holes and toe
problems.
Caused by:
1) Jointing and faulting.
2) Inclination and directional errors.
3) Bit skidding during collaring, deflection and bending, to
high feed force and low drill steel stiffness.
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How to Detect:
Face burden scanning compatible with drill hole deviation
equipment.
Action:
1) Knowledge of jointing and faulting to compensate for
deviation.
2) Better procedures for marking and collaring reducing
inclination and directional errors.
3) Reduce drill deflection, bending and reducing feed
force.
4) Reducing the hole length.
5) Select bits match rock type.
Drill-Hole Deviation
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V
H
K
B
Specific Drilling
Specific Drilling (q):
Drill meters per cubic meter
of broken rock.
Drill meters = H x number of holes/row
Volume = K x B x V
H x No of holes /row
K x B x V
q =
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Drilling Calculation
Descriptions Symbol
Example
• Max. annual limestone production t 2,500,000 ton
• Limestone density d 2.0 ton/m3
• Max annual limestone production m 1,250,000m3
• Burden × span V * E 4.0 × 5.5m
• Sub drill U 1.25m
• Bench height (Av) K 30.0m
• Hole depth (K+U) / cos α 31.75m
• Volume of rock / hole V * E * K 698.5m3
• Specific Drilling (Hole density) q 0.045Dm/m3
• Required drilling meter per year 56,250m
• Required drilled meter per day 187.5m
• Required number of holes per day 6 holes
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Explosives History
Safety fuse is invented by William Bickford, the founder
of Ensign-Bickford Company, to replace black powder-
filled cord (mining safety increases dramatically.)
1831
1865 Alfred Nobel, the founder of the oldest explosives
company, and he invents the first blasting cap.
1867 Alfred Nobel invents dynamite, another major step in
explosives safety and efficiency
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Characteristics of Explosives
Velocity (VOD):
- High explosive velocity (5000-7000m/sec): hard rock.
- Low explosive velocity (3500-4500m/sec): soft rock.
Strength:
- Relating to the strength of stander gelatin.
Sensitiveness: (propagation ability).
Cap Sensitivity:
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Density: (Kg/L).
Oxygen Balance:
Water Resistance:
Resistance to freezing:
Safety on Handling:
Environmental Properties:
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Governing Rules
Explosives right quality.
Cost.
Environment.
control of fly rock.
control of air blast.
control of vibrations.
control of wall damage.
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Variations of densities
1,26
1,24
1,22
1,19
1,16
1,10
1,15
1,05
1,00
0
1
2
3
6
7
5
4
11
12
10
8
9
13
14
15
16
meter
• Critical density of a given explosive is
defined as the density where explosives no
longer can detonate.
• Critical density occurs as a result of:
Dynamic pressure developed by previous
detonations in adjacent boreholes.
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Energy vs. Density
60,0
70,0
80,0
90,0
100,0
110,0
1 1,05 1,1 1,15 1,2 1,25 1,3 1,35 1,4 1,45 1,5
Density g/cc
Energymeasured(%)
Energy measured in 70 mm steal tubes
Energy & Density Relationship
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Emulsion Benefits
Optimum safety
No transportation of explosives
No explosives storage
No explosives before loaded in boreholes
Excellent water resistance
Environmentally frendly - optimum explosives fumes
Maximum flexibility regarding adjustment of energy and density on
site
High loading capasity, 100 - 300 kg/min
High accessability, hole length up to 40 m, up to 40 m difference
in level
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Historically, explosives have been classified as
primary and secondary, high and low, ideal and non-
ideal.
It is stored chemical energy and converted into a
mechanical work by the formed gases (reaction
products).
The term energetic material is perhaps better than
explosive, because it explains what it is all about.
The difference between a Detonation and a
Deflagration is “only” the energy release rate.
Explosives (Energetic materials)
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1 12 14 16
2723 35 39 40
atomsmoleculesmole /10023.61 23
14
Symbol
Atomicnumber
Name
Atomicweight[g/mole]
Explosive Energy
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Nitro - Glycerine Energy
H
ONO2C
H2
ONO2C
ONO2C
H2
24
1
22
3
22
5
29353 3 ONOHCOONHC
A complete ideal reaction of one mole Nitro-glycerine:
The temperature of reaction products is 2600 ºC and
the pressure is 4.8 GPa with a total energy of 6.4
MJ/Kg.
1 mole of the molecule
Nitro-glycerine contains 3
mole Carbon, 5 mole
Hydrogen, 3 mole
Nitrogen and 9 mole
Oxygen atoms.
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Diesel contains 10 times more energy than
Dynamite (45 MJ/Kg).
If 1 Kg of diesel is used in a car in 10 minutes
the total effect is 125 KW.
A typical effect of a Jet-engine is 8000 KW.
A Dynamite 25 x 380 mm cartridge has a weight
of 250 g and an energy of 1.1 MJ.
Then this cartridge detonates with a velocity of
4500 m/s its energy is released in 0.1ms. This is an
effect of 11 000 MW.
OHCOnOHC 2222612 1312
Energy and Effect
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The energy level must be sufficient to overcome the
structural strength of the rock and permit displacement.
Energy must be
confined long
enough after
detonation to
establish fractures
and enlarge existing
cracks and displace
material.
Optimum
explosive
performance
Energy
confinement
Explosive energy level
Energy
distribution
Energy must be
evenly distributed.
Optimum Explosive Performance
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Explosive energy level and distribution
The energy
level must be
sufficient to
overcome
structural
strength of
the rock and
permit
displacement.
Energy must
be evenly
distributed.
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Energy must be confined long enough after detonation to
establish fractures and enlarge existing cracks and
displace material.
Incident / Consequence:
Explosive gases of high temperature and pressure find the easiest
path to free face. As the rock-mass expands the pressure and
temperature drops. If the gasses went to early they cause air blast
and fly rock.
Caused by:
Burden variations, face cavities.
Drill deviation and positioning error.
Non homogeneous rock mass.
Bad timing.
Energy confinement & timing
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Explosive energy level and distribution
Incident / Consequence:
Excess or shortage of explosive energy will cause air blast, fly
rock, back break and vibrations.
Caused by:
Unfavourable shape of the bench.
Bench to stiff.
Unfavourable bench height, drill diameter, burden and spacing.
Bad selection of explosive,initiations system, drill bits and steel.
Drill deviation.
Cavities or weakness zones.
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Air-Bags:
It makes a part of the hole confined with
air. The stemming is kept in place by the
swelling action of the plastic air-bag,
after the chemical reaction of air-bag
gases .
The length of the air-deck is dependent
on the geological conditions, and the
presence of ground water in the blast
hole. It is often found with trial and error.
Reduction of the energy level in the blast
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Deck Charging:
The explosive divided by decks of
sand / gravel. Each deck is initiated by
a detonator & booster.
The energy of the explosive in each
deck may vary.
The delay time often increase from the
bottom of the hole to the top.
This method is often used to reduce
cost, vibrations and fragmentation.
Reduction of the energy level in the blast
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Explosive2 diameter, d [mm]
Explosive1 diameter, D, [mm]
Energy difference of a 32 mm Dynamite vs. 104 mm Dynamite in hole 104 mm,
which =(100%).
Decupling of explosive in the hole:
%5.9100100 5.4*2.1*104*104
5.4*2.1*32*32
2*2*
1*1*
2
2
energydensityD
energydensityd
Ediff
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VOD
VOD Recorder:
Measures the Velocity Of
Detonation which is only
the reliable instrument to
test the quantity and
performance of explosive
charges inside the blast-
hole, in term of explosive
velocity, as well as
determines delay time of
detonators, in order to
optimize blasting cost
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The proper delay between rows depends on:
42 ms 67 ms
Previous blast mucked outNo of rows Equipment
Delay Between Rows
Charge concentration
Rock proporties
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The electronic system is an important advance in
technology, enabling users to achieve the precision and
flexible timing benefits, with the easy connections of current
non-electric shock tube systems.
Electronic Detonators
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Incident / Consequence:
Front row moves to far, resulting in fly rock and air blast.
The muck pile profile is flat.
The fragmentation is coarse.
Timing is related to explosives energy and blastability.
Action:
1) Reduce the energy.
2) Reduce delay between the rows
3) Improve the blastability by changing the blast direction.
Timing
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Incident / Consequence:
Front row does not create enough space for the next row to expand
causing stemming injection, air blast and back break.
The muck pile profile is high, and compacted.
The fragmentation is fine.
This problem increase by an increasing number of rows.
Action:
1) Increase the energy.
2) Increase the delay between the rows.
3) Reduce the number of rows.
4) Improve the blastability by changing the blast direction.
Timing
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Dynamic burden movement and relief:
Optimal energy and timing of a blast is achieved if the front row moves
1/3 of the burden before the next row begins to move. This creates a
volume of 33% in front of the row for expansion.
The energy level must be sufficient to overcome the structural strength
of the rock and permit displacement.
This method takes the blastability of the rock into consideration
Burden movement can be studied in a video of the blast. High Speed
Digital Video Camera has 250-1000 frames/s (4-1ms between
frames). Objects of known sizes may be put on the blast for dimension
calibration. The video is captured to a computer with Motion Analysis
Software (MAS) that can advance or print frame by frame.
Timing Optimisation
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Bottom Charge
Bottom
charge
Qb
Bottom charge diameter
=
Hole diameter - appr 10 mm
Length of bottom
charge
=
V x 1,3 (m)
Cartridged Products
High explosive energy.
Cap sensitive.
Easy to charge into the hole.
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Normaly U = V
Increased stemming
gives less fly rock but an
increased number of
boulders and vice versa.
Stemming
Stemming U
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Incident / Consequence:
Air blast, Fly rock and loss of energy.
Action:
1) Increase the length of the deck.
2) Select correct size and quality of the material.
- Avoid fines and drill cuttings in the material.
0.7:BurdenlengthStemming
[mm]diameterhole0.05Size[mm]
The stemming of the hole does not prevent the blasting
gasses from ejecting trough the stemming.
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Muck pile shape.
Vibration.
Fragmentation.
Available equipment
ensuring efficient digging
and hauling.
Optimal Blasting
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Fragmentation best suited
for the down stream process,
and quality of the final product.
Blasting is the cheapest
method to crush rock.
Often a focus on reduction of
fines and oversize material.
Fragmentation
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Transforming intellectual property into cost / productivity
improvements by conducting and implementing structured
projects that deliver ongoing, measurable savings.
First step is to baseline the current processes.
Second step is to validate and agree on potential benefits of
identified drill and blast projects that directly effect downstream
processes.
Third step is to implement systems to lock in benefits for the long
term.
Fourth step is to regularly audit the process to ensure the benefit
accrues.
Optimal blasting a group approach
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Improve quality control of loading practices
Select explosive and initiation system to do the job
Select shape and layout of blast to optimum explosive performance
Optimise blast size, boundaries and pit slope stability.Mine
Planning
Blast design
Product
selection
Drilling
Loading
Blasting
Hauling
Processing
Drill holes at correct location and angel to the correct depth, min. deviation.
Optimise explosive performance, creating a fragmentation and muck pile
best suited for the down stream process and quality of the final product.
Max. Value
Maximize blasting value
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NE and SW blasting direction in this quarry did cause
adverse back break, poor fragmentation , air blast and fly
rock.
Mine planning
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Blasting directions of an isotropic rock with shallow dipping
joints & faults.
Blasting
direction
Example Fragmen
tation
Back-break
and Toe
Floor
A Poor Problems Problems
B Good Some
problems
Average
C Good Minor Average
D Good Minor Average -
Poor
Mine planning
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Blasting Direction
Blasting in direction (A) did cause damage to the
wall, massive boulders, poor floor and big
problems for the next blast.
The next blast was also shot in the same
direction, but to avoid similar result the 25 holes
by 16 rows blast was shot with a ~ 2 ms/m
burden delay between holes and a ~ 9 ms/m
spacing delay between rows.
A
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Blasting Direction
Helwan Limestone Quarry:
The cut of quarry face did not
respect the alignment of blast-
holes, sliding behind for more
than 18m, following the existing
fault plane.
The next blast was also shot in
the same direction, but to avoid
similar result the 7 holes by 3
rows blast was shot. The result
was excellent.
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Blasting results are often influenced more by geology
than explosive properties.
Geology Effects
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Bedding, jointing and faulting:
Influences fragmentation and boulder count, back break and wall stability.
Compressive strength:
Strength of rock under compression influences the production of fines close to
the hole.
Tensile strength:
Strength of rock under tension. Crack formation and fragmentation.
Poissons ratio:
The relationship of lateral deformation to longitudinal deformation, influences
wall control and back break.
Youngs modulus
The ability to withstand or resist deformation. Influences blastability.
Rock Impedance
The velocity that rock will transmit compression waves multiplied by the
density of the rock. Influences blastability.
Geology Effects
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Select shape and layout of blast
to avoid adverse edge effects, fly
rock and air blast enabling efficient
blasting and optimum explosive
performance.
Blast design
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A B
C D
E
A: Not bad. Some damage to
corners.
B: Very good shape utilizing to
free faces.
C: Damage to corners.
stemming ejection and air
blast.
D: Damage to corners. High
probability for stemming
ejection and air blast.
E: Box-cut = damage, air blast
and fly rock.
Bench design
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Hole angel.
Number of free faces.
Sub-drill.
Diameter of the hole.
Stiffness of the bench
Effects of Explosive Energy
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Bench design
• The broken rock needs 30 - 40
% extra volume for swell.
• Avoid 90° corners.
• Utilize free faces.
Select a shape, length to depth ratio to minimize back
break, stemming ejection and air blast.
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Bench Stiffness
The stiffness of the bench is the bench height divided by
the burden.
V
K
S
Stiffnessratio 1 2 3 4
Fragmentation Bad Medium Good Excellent
Air-blast Bad Medium Good Excellent
Fly-rock Bad Medium Good Excellent
Vibrations Bad Medium Good Excellent
Comments BAD DESIGN New
design if
possible
Increasing the
stiffness-ratio
above 4 does
not always give
a positive effect
K : Bench height [m]
V: Burden [m]