Exam (Blasting) 2026 With All Correct
Answers Passed Get A+
What type of explosive is most commonly used in Sweden? - Ans--The most
used type of explosive in Sweden is AN-based bulk emulsion
What is the main purpose of blasting? What negative effects should we
control while blasting? - Ans--The main purpose of blasting is extract ore in
pieces suitable for further handling (hauling, crushing, etc) while avoiding
damage to the remaining rock that would could stop the production of the
mine/quarry or the geotechnical works.
The negative effects that should be controlled are:
- Toxic fumes (in underground tunnels, the gasses should be ventilated)
- Ground vibrations (low frequency vibrations that could damage buildings)
- Fly rock (Can affect crack propagation in walls and may crack glass)
- Airblast
Why is stemming used in blastholes? - Ans--Stemming is used to contain
the gases of the explosion for sufficient time for the gases to fracture and
move the rock. Stemming is also to reduce the throw length from the blast.
Why is subdrilling used in bench blasting? - Ans--Subdrilling necessary to
break to grade. When the subdrill is to short this area of maximum tension
will be located higher up, and not break to the bottom of the floor. In order to
break a smooth, correct floor the subdrill have to be the correct length.
How is specific charge defined? Give a typical number for bench blasting. -
Ans--Specific charge is the volume of rock that can be blasted by 1 kg of
explosive. A typical number for bench blasting is q=0.5 kg/m3
Equation --> q=(mass of explosives in blast
hole,kg)/(Burden*Spacing*bench height, m3)
List some possible methods for ground vibration reduction - Ans--- Reduce
the weight of explosive blasted per delay. (Decking charge, decouple
charge, use hole by hole initiation, etc)
, - Reduce final vibration by using wave superposition.
- Damp the vibration waves.
What are the parameters of the Swebrec function? Give the expression for
P(x) - Ans--P(x)=1/ {1+ [ln(Xmax/x)/ln(X_max/x_50)]^b}*100
x_50= avrage fragment size
X_max= maximum limit of fragmentation size
b = undulation parameter
b=0,5(*x_50^0,25)*(ln(x_max/x_50))
The PPV-approach (Peak particle velocity) for blast damage has been
criticized a lot. Name at least two objections against using this method to
determine the blast damage. - Ans--PPV takes into account only the mass
of the explosive and the distance from the blast. An instantaneous initiation
of several charges gives a higher PPV because of charge cooperation, yet
field tests show that measured crack lengths are shorter.
The stress connected to PPV is accurate only in 1D or at the wave front.
Figure 2 shows different parts of a tunnel blast design.
a) What sequence do you suggest for the initiation of regions? (1p)
b) What is the reason behind different designs for side stoping regions and
upper stoping region? (1p)
c) Mention four reasons for using cautious blasting in the tunnel contour.
(1p)
(picture of a tunnel profile with contour, stoping, cut and lifters) - Ans--a)
1.cut
2. stoping left and right of the cut.
3. roof stoping
4. Contour holes
5. Lifters
b) When blasting the upper stoping holes there is a larger free face
available.
c) The extent of caution baslting deponds on the expected lifetime of the
tunnel. Using cautious blasting will propagate the following results.
1. Less dilution, better ore recovery
2. less support work, less bolting, less shotcrete or concrete to cast
3. Increased safety
4. Less rock to haul, saves time and money
Answers Passed Get A+
What type of explosive is most commonly used in Sweden? - Ans--The most
used type of explosive in Sweden is AN-based bulk emulsion
What is the main purpose of blasting? What negative effects should we
control while blasting? - Ans--The main purpose of blasting is extract ore in
pieces suitable for further handling (hauling, crushing, etc) while avoiding
damage to the remaining rock that would could stop the production of the
mine/quarry or the geotechnical works.
The negative effects that should be controlled are:
- Toxic fumes (in underground tunnels, the gasses should be ventilated)
- Ground vibrations (low frequency vibrations that could damage buildings)
- Fly rock (Can affect crack propagation in walls and may crack glass)
- Airblast
Why is stemming used in blastholes? - Ans--Stemming is used to contain
the gases of the explosion for sufficient time for the gases to fracture and
move the rock. Stemming is also to reduce the throw length from the blast.
Why is subdrilling used in bench blasting? - Ans--Subdrilling necessary to
break to grade. When the subdrill is to short this area of maximum tension
will be located higher up, and not break to the bottom of the floor. In order to
break a smooth, correct floor the subdrill have to be the correct length.
How is specific charge defined? Give a typical number for bench blasting. -
Ans--Specific charge is the volume of rock that can be blasted by 1 kg of
explosive. A typical number for bench blasting is q=0.5 kg/m3
Equation --> q=(mass of explosives in blast
hole,kg)/(Burden*Spacing*bench height, m3)
List some possible methods for ground vibration reduction - Ans--- Reduce
the weight of explosive blasted per delay. (Decking charge, decouple
charge, use hole by hole initiation, etc)
, - Reduce final vibration by using wave superposition.
- Damp the vibration waves.
What are the parameters of the Swebrec function? Give the expression for
P(x) - Ans--P(x)=1/ {1+ [ln(Xmax/x)/ln(X_max/x_50)]^b}*100
x_50= avrage fragment size
X_max= maximum limit of fragmentation size
b = undulation parameter
b=0,5(*x_50^0,25)*(ln(x_max/x_50))
The PPV-approach (Peak particle velocity) for blast damage has been
criticized a lot. Name at least two objections against using this method to
determine the blast damage. - Ans--PPV takes into account only the mass
of the explosive and the distance from the blast. An instantaneous initiation
of several charges gives a higher PPV because of charge cooperation, yet
field tests show that measured crack lengths are shorter.
The stress connected to PPV is accurate only in 1D or at the wave front.
Figure 2 shows different parts of a tunnel blast design.
a) What sequence do you suggest for the initiation of regions? (1p)
b) What is the reason behind different designs for side stoping regions and
upper stoping region? (1p)
c) Mention four reasons for using cautious blasting in the tunnel contour.
(1p)
(picture of a tunnel profile with contour, stoping, cut and lifters) - Ans--a)
1.cut
2. stoping left and right of the cut.
3. roof stoping
4. Contour holes
5. Lifters
b) When blasting the upper stoping holes there is a larger free face
available.
c) The extent of caution baslting deponds on the expected lifetime of the
tunnel. Using cautious blasting will propagate the following results.
1. Less dilution, better ore recovery
2. less support work, less bolting, less shotcrete or concrete to cast
3. Increased safety
4. Less rock to haul, saves time and money
