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www.isee.org
Volume 30 Number 4
July/August 2013
The Official Publication of the International Society of Explosives Engineers
Inside:
Double Deck Blasting for Rapid
Tunnel Advance in Hong Kong.....................6
Controlled Shaft Sinking Using
Electronic Delay Detonators and
Water Ballast.............................................26
20th Annual Photo Contest.......................36
The Journal of Explosives Engineering
Published by International Society
of Explosives Engineers
30325 Bainbridge Road
Cleveland, Ohio 44139
www.isee.org
www.isee.org
Publisher
International Society of Explosives Engineers
Editor
Dede Manross
[email protected]
Contributing Writers
R.B. Hopler
Bill Reisz
Board of Directors
President
John E. Capers
Vice President, Administration
Michael J. Koehler
Vice President, Technical
Jack W. Eloranta
F E AT U R E S
6
Executive Director
J. Winston Forde
Director of ISEE and SEE Education Programs
Buck Hawkins
Director of Communication
Dede Manross
Meetings and Conference Manager
Lynn Mangol, CMP
This article describes the products and techniques used in an assessment consisting of
three double deck blasts at a large rail tunneling project under construction on Hong
Kong Island.
Managing the blast site (The Known Unknowns).
26 Controlled Shaft Sinking Using Electronic Delay Detonators and
Water Ballast
Located in a densely populated area in close proximity to numerous sensitive receivers, it was decided originally that blasting was not feasible at the King George Shaft in
Hong Kong.After a geographical information analysis and blasting assessment report
was submitted to authorities by the subcontractor, it was concluded that by using
innovative blasting techniques using electronic detonators and a water ballast, blasting
would be feasible and it was approved.
Secretary
Alastair C. Torrance
Directors
Nancy C. Allen
Josef (Boet) E. Coetzee
Kevin J. Hachmeister
Algernon R. Hackett
David Harrison
Keith M. Henderson
Richard M. Hosley, Jr.
Braden Lusk
Cam Thomas
Hans E. Wallin
Kirk Whitaker
Dean A. Wiegand
Double Deck Blasting for Rapid Tunnel Advance in Hong Kong
16 Safety Talk
Treasurer
James P. Daley
Past President
Ron J. Elliott
July/August 2013
Volume 30 Number 4
36 20th Annual Photo Contest
Highlights an honorable mention winner:WAC Bennett Dam.
D E PA RT M E N T S
4
From the Executive Director
ISEE will be celebrating its 40th Anniversary in 2014!
17 Chapter News
Members of the Mississippi Valley Chapter conducted a grass roots effort to provide
input to the proposed Explosives Safety Act in Kansas - SB 227.
18 Industry News
20 Calendar of Events
A list of upcoming events in the explosives industry.
22 Explosives, 100 Years Ago, More or Less
A trip through the anthracite coal mines.
On the Cover: Controlled shaft sinking
project in Hong Kong using electronic
delay detonators and water ballast. See
story page 26.
Marketing Manager
Bill Wahl
Office Manager
Mary Spena-Bosch
Membership Coordinator
Ruth Schaefer
Publications Coordinator
Lauren Creneti
All correspondence should be directed to:
International Society of Explosives Engineers,
30325 Bainbridge Road, Cleveland, Ohio 44139
Telephone: (440) 349-4400. Fax: (440) 349-3788.
E-mail: [email protected] WebSite: www.isee.org
Copyright ©2013 Society of Explosives Engineers, Inc., dba International Society of Explosives Engineers
The Journal of Explosives Engineering, published six times per year, is the official publication of the International Society
of Explosives Engineers.The Society is not responsible for opinions expressed and statements made by authors in articles
or advertisements published in the Journal. ISEE assumes no responsibility for the completeness, accuracy, or conclusions
reached in any of the articles or items published in this Journal.
Since the information is unique and because each job site is different, information presented in this Journal may not apply
to your specific field situation. Readers are cautioned to carefully consider ideas presented and decide for themselves if
the procedures described are safe and appropriate for the intended use.The International Society of Explosives Engineers
cannot be responsible for the specific application of the information presented. Also, remember to always consult the
manufacturer of the product(s) you are using for recommended practices.
Mention in this publication of a commercial or proprietary product does not constitute an endorsement or recommendation for its use. Registered names, trademarks, logos, artwork, photographs, etc., used in this publication, even without
specific indication thereof, are to be considered protected by law.
Yearly subscription rates: $95 U.S.A., $115 all others (International Air Mail). All members of the Society receive a complimentary subscription.
The Journal of Explosives Engineers
July/August 2013
From the Executive Director
40 Years and Counting!
By J.Winston Forde
Executive Director
ISEE
Four decades of
staying in business is an accomplishment
worth celebrating.
Whether
the business is
a
multi-million
dollar
venture
or a small family-owned enterprise,
40 years is a long time to remain a
viable business entity, demonstrating a sustained record of success.
In August 1974, the International Society of Explosives Engineers (ISEE)
began to deliver on its mission to advance the art and science of explosives engineering. For four decades,
through periods of opportunity and
challenge, ISEE has served its members with pride.
Today we are over 4,000 members
strong! For 40 years, our members
have been organizing for change on
the matters that affect the explosives
industry – important issues that pertain to regulation and government affairs, education and training, safety and
security, public education and public
relations. ISEE members and supporters are the reason why we are celebrating a new milestone – our 40th
anniversary.
From Feb. 9 – 12, 2014, ISEE will
sponsor the 40th Annual Conference
on Explosives and Blasting Technique
at the Hyatt Regency Denver at the
Colorado Convention Center in Denver, Colorado. Launched in 1975, the
Annual Conference on Explosives and
Blasting Technique is the world’s largest forum for commercial explosives
and blasting technology, presenting
the latest developments and bringing
together researchers, educators, field
blasters and manufacturers.
The 2014 Annual Conference will
be a celebration of our achievements
over the past 40 years. Our work has
made a lasting impact on the working
women and men in our industry. We
have much to celebrate because of
4
you. Your support, whether long-term 40th year anniversary, don’t forget
or recent, has enabled ISEE to grow to get your best shots – no pun inand prosper over the past 40 years.
tended. We will be looking for videos
As a follow-up to the 2013 Confer- to include in the Blasters R Us Video
ence, the SEE Education Foundation Roundup and picture submissions for
Live Auction was a success! Thanks to the Photo Contest.
all who participated and to those who
Your attendance at ISEE’s 40th Andonated, the Foundation was able to nual Conference will be a time to conraise over $25,000, which will be used nect with peers who can make a difto award academic scholarships to ference in your business and heighten
deserving students. When you think your professional visibility. Its industry
about the items donated like NASCAR functions like this that give business
and NCAA final four tickets,the bidding people the tools they need to build
action was truly aggressive. Since the new professional relationships and
live auction was such a success, there generate business opportunities.
are plans to do it again in 2014! That
We look forward to seeing you in
being said, we are once again reach- Denver!
ing out to the general membership
for auction item
donations. You can
contribute online
at our secure site:
www.isee.org or
with RockMore
contact the SEE
Education Foundation at:
Drill More
SEE Education
Foundation
30325 Bainbridge
Road
Cleveland, OH
44139
440.349.4400
While we’re discussing the Conference, mark your
calendars – conference booth sales
begin in July. Get
the best booth position you can by
being one of the
first to secure your
booth space. Be
on the lookout for
announcements
coming from ISEE
Conference Manager Lynn Mangol.
Because we will
be celebrating our
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July/August 2013
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Double Deck Blasting
for Rapid Tunnel Advance
in Hong Kong
By Osamu IWATA, Katsuhiro KAMEYAMA, Rohan Stevens, and Jinming Liao.
In densely populated cities such as Hong Kong, where unoccupied space is becoming more
valuable as the population grows, city planners are more often looking to underground space to
meet the increasing need for transportation and services. Given the dense population of people,
amenities, historical buildings, and high-rise buildings above or near such underground space, it
is essential to minimize any disturbance and potential damage during construction. Hence, the
excavation of hard rock to develop such underground space can be highly restricted, expensive,
and time consuming.This is the case for many of the tunnels currently being excavated by drill
and blast directly underneath Hong Kong’s busiest business districts and most popular residential areas.
Double deck blasting is a blasting method that takes advantage of the latest blasting technology to have an immediate effect on advance rates without increasing blast induced ground vibration and the associated risk of damage and disturbance. Double deck blasting refers to drilling to
a depth that enables the firing of two tunnel rounds in a single blast, by loading each blasthole
with two independent charges separated by an inert material. This method has the potential
to double the advance per blast, halving the amount of blasts required, halving disturbances to
neighbours, and halving disturbances to the construction schedule while still controlling vibration levels for a given length of tunnel.
Double deck tunnel blasting introduces new challenges such as increased loading complexity,
the need for an inert deck to separate two explosive charges capable of preventing both desensitisation and sympathetic detonation and doubling the number of charges requiring an individual
firing time. Through the combination of a specially sequenced loading method, production of
crushed aggregate stemming plugs, the use of a sophisticated digitally programmable electronic
initiation system and some in-field optimization, the challenges introduced by double deck blasting can be overcome, opening the door for a new era of rapid civil tunnel advance.
This article describes the products and techniques used in an assessment consisting of three
double deck blasts at a large rail tunnelling project under construction on Hong Kong Island.
6
July/August 2013
Introduction
Before blasting can commence on any tunnelling project in Hong Kong, a Blasting Assessment Report (BAR) is
conducted. The broad aim of a BAR is to assess the impact
of blasting on the surrounding sensitive receivers. Sensitive
receivers are anything that may be damaged or disturbed
by blasting. Common sensitive receivers are structures
such as buildings and bridges, manmade slopes and retaining walls, natural slopes and services. The BAR assesses all
environmental impacts of blasting including flyrock, noise,
ground vibration, dust, and fumes. However, in civil tunnelling it is generally ground vibration that has the greatest
impact on blasting efficiency.
Focusing on ground vibration, the author of the BAR
compiles a list of all sensitive receivers along the tunnel
alignment, including precise location coordinates and a
vibration limit for each. The location of each sensitive receiver can then be compared to the location of the tunnel,
generating a list of distances (R). Using these distances and
the nominated vibration limit (PPV) the scaled distance formula is used to create a table of allowable maximum instantaneous charge weights (W) for the project.
Where:
PPV – Peak particle velocity (mm/s)
K – Rock transmission constant
R – Distance between blast and sensitive
receiver (m)
W – Maximum instantaneous charge
weight (kg)
B – Attenuation exponent
Values for K and B recommended by the Hong Kong
government for predicting ground vibration to the 84%
confidence level are 644 and 1.22 respectively. These values are based on blasting records kept between 1984 and
1992 in Hong Kong. Ultimately all BARs need to be granted
approval by the Hong Kong government thus all contractors and consultants use these figures to generate the table
of tunnel chainages and allowable Maximum Instantaneous
Charge (MIC) weights for a given project. After final approval the Hong Kong government uses the BAR as a tool
to govern the contractor’s blast designs. Even if the contractor’s blasts consistently generate vibration below the allowable limits, the MIC cannot be increased until a statistically
reliable data set is collected and the data is regressed to
produce new values for K and B. Subsequently a new table
of MICs can be generated and submitted in a report to the
Hong Kong government for review. Thus MIC increase is
possible but difficult where the MIC is already very low,
the process itself is time consuming and it does not offer a guaranteed and immediate increase in round length.
Consequently in most cases the contractor will resign to
designing blasts that comply with the initial table of MIC
presented in the BAR. Where this specified MIC restricts
the length of the round, contractors are left searching for a
method to maintain and increase productivity while adhering to the BAR specified MIC.
Given the proximity of many of the tunnels to sensitive
receivers, the BAR for a particular project of interest identified sections of tunnel where blasting must be carried out
using an MIC as low as 0.2 kg (0.44 lb). Such specifications
are understandable given Hong Kong’s historical blasting
data, however, they severely restrict the tunnelling advance
rate. Using conventional single deck blasting methods, a
0.2 kg (0.44 lb) MIC restricts advance to around 0.5 m (1.6
feet) per round. Double deck blasting will potentially allow doubling the advance for every blast fired without increasing the MIC; hence halving the amount of blasts fired
for a given length of tunnel; and halving the number of associated disturbances to neighbours and the construction
schedule.
Double deck blasting refers to firing two rounds in a
single blast, by loading each blasthole with two independent charges separated by inert material (see figure 1), to
allow an increased production rate while maintaining the
BAR specified MIC.
Figure 1. Double deck concept.
July/August 2013
7
Challenges Introduced By Decked Tunnel
Rounds
While the concept is simple, execution of a double
decked blast with a conventional initiation (pyrotechnic
signal tube delays) brings additional challenges:
1. A greater number of charges, each requiring a different
firing time.
2. A more complicated surface tie-up increases risk of
misfires due to surface cut off.
3. A complicated tie-up is difficult to check, increasing
the risk of misfires due to operator error.
4. Loading complexity and increased loading time.
5. Lack of shotfirers with the skill and understanding to
load and fire complex designs in the production environment.
6. Conventional sequencing can be carried out on a two
dimensional platform, an additional deck requires the
designer to consider sequence and relief in a third dimension.
7. Shock desensitisation between charges can cause misfires.
8. Sympathetic detonation between charges may cause
multiple charges to fire simultaneously, generating high
ground vibration.
9. Sourcing appropriate inert material for use as charge
separation, able to withstand immense heat and pressure with locking characteristics under pressure, while
being easy to install in a horizontal hole. Must be capable of preventing items 7 and 8.
10. Appropriate charge separation distance to prevent
items 7 and 8.
Overcoming the Challenges – Product
Selection
Using a conventional non-electric initiation system the
blast designer can only choose from pre-determined delays, limiting control over sequencing and burden relief.
The design, charging and tie-up for this type of initiation is
complicated, elevating the potential for errors and misfires.
Therefore the use of a non-electric initiation system was
deemed to be impractical and too high risk for introduction into the tunnelling production cycle with the available
workforce. Study of potential initiation systems indicated
that the simplest and safest way to overcome the first three
items would be to utilize programmable electronic blasting
system (EBS). An EBS allows complete flexibility in design
firing time and the accuracy required to fire at the designed
time. The EBS chosen for this project is accurate to 0.1%
of its nominated firing time and can be programmed in 1
ms increments from 0 ms to 10,000 ms. This guarantees
the correct firing sequence and avoids having more than
a single charge firing in any instant, even with the significantly greater number of charges required. Further the
EBS allows two way communication with each detonator,
giving confidence that all connections are correct before
firing and diminishing the risk of misfire due to operator
error. Also, an EBS provides a full ‘burning front’ eliminating
the possibility of misfires due to surface initiation cut off
during the blast.
In order to meet and guarantee the strict and relatively
low MIC, packaged emulsion explosives were an obvious
8
choice as the principal explosive. Packaged emulsion in different cartridge sizes is widely available in Hong Kong and
is ideal for gradually changing MIC requirements.
The middle stemming (inert) deck plays a critical role
in separating the two charges in each hole. It must protect
the second deck so that it functions normally after the first
deck has fired.The most common material in use for stemming is crushed aggregate, however, the use of aggregate in
a horizontal hole compared to a vertical hole presents new
challenges. Gravity will no longer assist in pouring the material into the hole, nor will it assist in keeping pressure on
the aggregate to lock it in position. To solve this problem,
plastic lay-flat tubing with outer diameter within 5 mm of
the hole diameter was filled with crushed aggregate (passing size 10-12% of hole dia.) to manufacture “stemming
plugs” to the design stemming length (figure 2). After insertion, tamping forces the stemming plug to become fully
coupled with the walls of the hole, locking into position.
Overcoming the Challenges – Process Design
Deck charging has been used previously in mining and
civil applications so it is known to be achievable. There is
however no scenario known to the authors where decking
has been used in horizontal development beyond the trial
scenario. It was desired to do more than assess if it was possible to fire double deck rounds but to develop a method
for doing so that could be implemented in the contractor’s
production cycle with the existing blast crews.
Shock desensitisation is known to be most likely in wet
confined conditions as the incompressible nature of water
means it has excellent shock transmission characteristics.
Holes were drilled looking up a minimum of one degree
to ensure they would be well drained, also allowing some
draining of the rock mass to be blasted. Further, it was decided to use computer controlled drilling to ensure all of
the second charges were located in a common plane, minimizing the risk of disruption between holes.
To meet the requirement to keep the loading and tie-up
process simple, the eDevTM Electronic Blasting System was
selected because it has a simple delay-by-numbers mode.
This mode enables the blast designer to implement a complex timing regime hidden behind a basic delay number
sequence that underground miners are familiar with. The
blast designer can devise a custom delay range by completing a 3 column table (delay table) consisting of the following columns:
• Delay Number – The numbers used to sequence the
blast at the face
• Increment – The time between charges with the same
delay number
• Offset – The time between consecutive delay numbers
The shotfirer is merely required to assign a delay number to each charge, as he has been trained to do previously
with conventional systems. The schematic below shows a
typical delay-by-numbers initiation design used by the shotfirer at the face, sequencing with ascending numbers on a
two dimensional platform.
By adopting this EBS the exact same delay numbers
can be used for the front and rear deck in each hole, yet
the software allows complete flexibility and control over
July/August 2013
Figure 2. Inert separation (stemming).
actual programmed firing times. Therefore, after drilling is
complete, the shotfirer can follow the previous practice
of marking out delay numbers on the face. Following, the
blast crew are simply required to load the rear deck (B)
as they would have previously loaded a conventional blast,
taking special care to install the correct length of stemming.
After assigning delay numbers to deck B, according to the
face mark out, the process is simply repeated for the front
deck (A).
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1
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Each detonator in the system has a unique factory assigned ID number.This means that the tie-up or connection
order after charging is complete is not important. It’s simply a matter of clipping all detonators onto a harness wire.
The system is then capable of ensuring all detonators are
connected and responding, and if a detonator is missing or
not clipped on properly this is identified by the system.This
is a contrast to the conventional system where the face tieup is critical in determining the initiation sequence.
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Figure 3. Delay by numbers initiation design.
Figure 4. Two-step process design based on existing skill set.
10
July/August 2013
ISEE - Half Page Vertical for Instantel.ai 1 1/27/2010 3:32:30 PM
Evaluation Program Objectives
Based on the chosen products and technique, a threeblast evaluation program was planned with broad aim of
assessing the following:
1. Advance per round fired.
2. Capability of the method to fit into the production cycle
with the operational resources currently available.
3. Any increase in risk such as misfires or excessive ground
vibration.
Charging
The starting point for the blast design was the smallest
MIC expected later in the project – 0.2 kg (0.44 lb). Based
on a commonly used rule of thumb for dry holes, the stemming length should be 20 to 30 times the hole diameter.
For a 45 mm (1.8 inch) diameter hole used this equates
to 0.9 m (3 feet) of stemming between the two charges in
each hole. This length is also the effective burden of the
second explosive deck, and it was clear to the blast designers that 0.9 m was far too much for a 0.2 kg charge to break.
Therefore, the blast designers decided to work outside the
commonly accepted rule of thumb, based on the fact that
the charge weights were well outside commonly used values.
The inter-deck stemming was scaled down based on
equation 2.
C
M
Y
CM
Equation 2.
MY
Where: CA = actual charge weight (kg) [0.2]
C8 = charge weight equivalent to 8 hole
diameters of same product density (kg) [0.7]
D20 = 20 hole diameters (m) [0.9]
S = inter-deck stemming length (m)[0.3]
CY
CMY
K
The resulting charge design chosen for the first and
second blasts is shown in figure 5. Note that the 32 mm
diameter packaged emulsion is decoupled in the 45 mm diameter blast hole.The third blast was designed with a MIC
of 0.4 kg and scaled out accordingly.
Blast 1
In the first evaluation blast, the six cut holes were fired
in a hole by hole sequence (charges A and B in each hole
were fired), followed by the remaining deck A charges
across the entire face, and then the remaining deck B charges. The section firing sequence and angle of initiation in
figure 6 shows this, ignoring the cut area this blast was
fired as two separate rounds within one blast, one after the
other.
Loading and tie-in time for this blast was 225 minutes
for 358 decks. This productivity was deemed to be acceptable and within the time it may take to load two separate
single decked blasts. There were no notable safety issues
or increase in risk during the loading and firing sequence.
The actual MIC for this section of tunnel, as specified by
July/August 2013
11
Figure 5. Initial charge design.
the BAR, was 3.8 kg so the absolute values of ground vibration measured (PPV below 1mm/s) were not useful for
comparison purposes. The six cut holes had achieved the
desired 100% pull length, however holes surrounding the
cut and majority of the blast only appeared to pull around
50-60% of the 1.0 m (3.3 feet) drilled length.
Blast 2
crease in risk. All measured ground vibration was below 1
mm/s or monitor thresholds were not triggered.The majority of this blast pulled 100% or more than the drilled 1.0 m
length. There were very few small butts (sockets) remaining in the face.
Blast 3
Holes surrounding the cut were moved closer, reducing
burdens, and the initiation sequence was changed substantially. Commencing with hole by hole firing the angle of
initiation was gradually opened, as shown in figure 7. In
three dimensions this results in expanding conical angles
of initiation.
Loading and tie-in time for this blast, also consisting of
358 decks, was 185 minutes; a small amount of experience
with the previous blast offered immediate improvement
in productivity. There were no notable safety issues or in-
The MIC for this blast was doubled from 0.2 kg (0.44 lb)
to 0.4 kg (0.88 lb). Due to Hong Kong government regulations the blast design and associated explosives order was
submitted prior to firing the earlier two blasts. Given the
results of the previous two blasts it was expected that the
design powder factor (reduced from 1.77 kg/m3 in the previous two blasts to 1.36 kg/m3 for this blast) was too low.
However, as the design and explosives order were already
submitted it was not possible to increase the explosives
quantity. This left two options – to cancel the blast or continue as designed and gain further practical experience and
Figure 6. Blast 1 - initiation design.
12
July/August 2013
July/August 2013
13
knowledge of the lower energy scenario. Continuing as designed, an initiation sequence comparable to the previous
blast was used.
Loading and tie-in time for this blast, 264 decks, was
130 minutes - again showing vast improvement with experience. There were no notable safety issues or increase
in risk due to deck loading. No notable increase in ground
vibration even though the MIC was doubled. As expected
before firing, due to the low powder factor this blast pulled
around 60% of the drilled 1.6 m (5.2 feet) length.
cess. In preparation for this, software has been developed
to expedite the design process, allowing the blast designer
to model the initiation sequence on a three dimensional
platform, automatically updating the entire initiation sequence as the designer makes changes.
While the technique is proven to work there is great potential for increased tunnel advance rates if the technique
is progressed to greater charge weights and round lengths
or in using additional decks to increase round length even
further.
Conclusion and Future Scope
About the Authors
Using double deck methods, the overall tunnel advance
rate was increased without any adverse impact on the surrounding highly sensitive area based on what would be
achieved with conventional blasting and the same MIC.
Loading times for double deck blasts were within the time
taken to load two conventional blasts with promising improvement in blast crew productivity observed over three
blasts.With majority of the charging and tie-in work carried
out by the existing blast crews and no notable increased
risk it has been shown that the double deck design principal, coupled with the right products and processes can be
implemented into the tunnel production cycle to improve
the advance rate where MIC is highly restrictive.
The joint venture responsible for this particular tunnel
intends to put the double deck process into production
soon for a length of tunnel where the BAR has identified
the MIC as low as 0.2 kg (0.44 lb). This will allow further
optimization of the blast design and implementation pro-
14
Osamu IWATA, Nishimatsu Construction Co.,LTD, HK
Katsuhiro KAMEYAMA, Nishimatsu Construction Co.,LTD, HK
Rohan Stevens, Orica Mining Services, Global
Jinming Liao, Orica Mining Services, HK
This article was presented by the authors at ISEE’s 39th Annual
Conference on Explosives and Blasting Technique in February,
2013 in Fort Worth, Texas. This paper has been updated from its
original version. The opinions and ideas expressed are not necessarily those of the International Society of Explosives Engineers
or the editorial/publishing staff of the Journal of Explosives
Engineering. See “The Proceedings of the 39th Annual Conference
on Explosives and Blasting Technique” for full text and references
for this paper.
July/August 2013
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Safety Talk
Managing the blast site at almost
any operation can be a daunting task.
There are so many details that must be
observed, understood, and acted upon.
It goes without saying that there are no
two locations that have the exact same
challenges and concerns. The level and
the extent of these challenges can vary
widely.
With the summer vacation season
coming up, you may find yourself in
the unenviable position (or the adventure; depending on your perspective)
of filling in for another blaster at an
unfamiliar operation.Whenever you are
coming in cold to manage an unknown
location, you should first take the time
necessary to learn as much about the
site conditions as possible. Depending
on the size and complexities involved,
you may want to come in several days
in advance to work with the blaster in
charge and the on-site persons you will
be working with. It will be to his or her
benefit as much as your own.
No blaster wants to come back after a much needed vacation to find
their job in total chaos. I’ve heard many
blasters say (myself included) that it
takes too much effort to take time off
because when they come back they
will have to work twice as hard for the
next few weeks just to get caught up
and fix the mess left behind. Inevitably
there will be blast reports to review
and file, inventory logs to check, order
receipts, equipment maintenance and
repairs, blasting complaints, regulatory
oversights, housekeeping, and all sorts
of other issues to deal with. Not to mention that you might be pushed to make
up for production that was lost during
your absence. In this business it is certainly true that your work doesn’t stop
just because you’re away.
Situations like this can easily create
an unsafe and stressful working environment. For the fill-in blaster there
are many variables to consider, such
as unfamiliar geology, blast design parameters, personnel issues, equipment,
underground utilities, vibration sensitive neighbors or structures, monitor16
Managing the Blast Site
(The Known Unknowns)
Wm. J. Reisz
ing sites, explosive products, initiation
systems, permit restrictions, blast area
security and warning signals, site communications, and firing procedures just
to name a few. Any of which by itself
or in combination with another could
lead to a serious and often unrecognized risk.
Although certain Best Practice
guidelines are applicable to everyone, it
is extremely difficult and often impractical to set standards that will protect
everyone on every blast site. We cannot completely remove every risk in
every situation, even under the best of
circumstances. But we can and we do
minimize these risks by recognizing
and acting upon known risk factors.
The risks are inherently higher whenever we are dealing with the unknown.
As Donald Rumsfeld once said, “…
there are known knowns; there are
things we know we know. We also
know there are known unknowns; that
is to say we know there are some things
we do not know. But there are also unknown unknowns -- the ones we don’t
know we don’t know.” Somehow in this
context, his awkward assessment may
be worth further consideration.
Even in a situation where one may
have a great deal of familiarity of a blast
site, there are still known and unknown
risk factors. Rather than relying totally
on our vast knowledge of the known,
we must always be aware that unknown
conditions exist, and remain vigilant in
our duty to learn what we don’t know.
Some things we learn the hard way. It’s
often preferable to build in a substantial
safety margin to help alleviate the unknown potential risks.
If given the task of managing an
unfamiliar blasting operation, a strategically guarded approach would be
advisable. Keep in mind that some of
your preferred techniques that may
work very well in one location may not
work as well in this particular case. If
your personal objective is to come in
and reinvent the wheel and become a
hero, you may be unwittingly inviting
trouble. One should never allow the
high regard in which we hold ourselves
July/August 2013
to get in the way of good judgment.
In most cases, you should carefully consider the advice
and direction of the blaster or site manager that you’re filling
in for.The value of his or her experience should not be overlooked or easily dismissed. The exception would be in the
case where there is a known history of frequent incidents
and unsafe work practices. You must be familiar with the local rules and regulations and legally authorized to blast and
handle explosives for the location you will be working. And
without exception, you should never accept a blasting position for which you are not fully qualified.
With these thoughts in mind – work safe, work smart, and
have a great vacation.
Chapter News
with Federal statues, a process to keep up with new technologies or legally established precedent, and reducing the proposed fees and other items that would make the proposed
legislation a better platform for regulating the industry. That
same representative group also met a second time with the
Fire Marshall’s working group and has begun the process of
evaluating NFPA 495, 2013 edition. At this time the working
committee is close to wrapping up our editing and should
soon have a completed set of regulations that can then be distributed more widely for general comment. Once that work
is completed we think the Fire Marshall will submit a new
bill to again give the KS Fire Marshall’s Office authority to
regulate explosives in the state.
Until a new law is passed by the Kansas Legislature the
Fire Marshall’s office will only be regulating storage of explosives.
- Article contributed by Phil Porter
Explosives Safety Act in Kansas –
Update to SB 227
On March 6th the Kansas Fire Marshall surprised both
the Kansas Senate Federal and State Affairs Committee and
representatives from the Heartland Chapter of ISEE and
other concerned users of explosives by stating that his office does not have the proper statutory authority to regulate
explosives. After quickly recovering from the stunning admission, statements opposing the Fire Marshall’s new legislation were given by Ed “Woody” Moses, Executive Director
Kansas Aggregate Producers Association (KAPA); Phil Porter,
Buckley Powder Company and President Heartland Chapter; Russ Pilshaw, President and Owner PEXCO; Kelly Briggs,
President – COO, Bayer Construction Co.; John “Doc” Holiday,
Operations Manager,Austin Powder Company; Keith Henderson, Technical Manager Buckley Powder Company and ISEE
Board of Director; and Steve Johnson, Production Manager,
Hunt Martin Materials. Each of the speakers took slightly different approaches but opposed the new legislation on the
following grounds.
1. It gave too broad of powers to the Fire Marshall’s Office
to promulgate rules
2. It did not include an Industry Advisory Board
3. It would not provide the ability to stay aligned with
technological changes or industry standards
4. It placed additional and redundant layers of rules and
regulations on the industry
5. It did not provide a mechanism to keep from re-regulating federal standards
6. It contained fees that were excessive and not similar to
other states in the nation
7. It would not improve or enhance the safe use of explosives
The senate committee that received this proposed legislation also seemed skeptical and assigned their committee
legal counsel to provide them with a separate analysis of the
authority or lack thereof.
Since that morning, the Fire Marshall met with a representative group of explosives users and has agreed to pull
his bill for this session of the legislature. He also addressed
our biggest concerns and “in principal” is agreeing to include
in a re-written piece of legislation that includes an Advisory
Board, language that would align all present and future rules
July/August 2013
17
Industry News
RAM, Inc. to Present Blasting
and Explosives Safety
Training Seminar
Powell, Ohio USA – RAM, Inc., has
announced the dates for its annual fall
Blasting and Explosives Safety Training (BEST) Seminar.The two-and-a-half
day continuous education training session will be held at the South Dakota
School of Mines in Rapid City, S.D.,
Sept. 4-6, 2013. The final day of the
seminar will be capped by a special
night blast at the Crazy Horse Memorial on Sept. 6 for all attendees.
RAM, Inc.’s enhanced BEST Seminar is designed specifically for those
industry professionals who work with
explosives – explosives engineers,
drillers, field crews, safety personnel
and drill and blast engineers – and it
helps attendees comply with state and
federal regulations. Upon completion,
each BEST course attendee will receive a course certificate and a manual
with valuable information that can be
used in the field. All attendees will receive 20 continuing education (20 CE)
hours.
For 40 years, BEST seminars have
advanced safe operating practices
for more than a thousand attendees
worldwide who work with explosives.
Taught by instructors with decades of
experience in their respective fields,
the BEST course educates attendees
on explosives safety and application,
hazard recognition, accident prevention, and regulatory and new product
updates.
The training seminar
includes extensive instruction covering: comprehensive safety instructions for commercial explosives and
blasting; updates on electronic blasting systems and supporting technologies; regulatory updates by specialists
from the Bureau of Alcohol, Tobacco,
Firearms and Explosives (BATFE),
Mine Safety and Health Administration (MSHA) and U.S. Department of
Transportation; and tours of the Crazy
18
BEST class at Crazy Horse Memorial.
Horse Memorial, Deadwood and Mt.
Rushmore.
An advanced course registration
discount is available through July 31,
2013; visit www.ramets.com for full
course and registration fee details.
Course topics have been selected to
offer value to all professionals with
varied experience levels, from individuals with decades of experience
to those just entering the explosives
industry.
July/August 2013
Montabert Micro CPA Drill
Breaks Ground in North
America
Suwanee, Ga. USA– Tramac by Montabert broke new ground in Fredricksburg, Texas, with its new Montabert
Micro CPA drill. Representatives from
Montabert and Dallas Drilling and Hydraulics joined Montabert customer
Patricia Donato of EnFuse Inc. to witness the new product in action on an
EnFuse jobsite. “We are excited about
the Micro CPA drill,” Donato said.“The
technology and engineering behind
this drilling attachment is second
to none and we are very pleased to
have been the first to purchase one in
North America!”
The CPA drill covers a large area
and can drill wherever you can reach,
saving on moving and setup time. In
addition, the attachment can be radio
controlled and an efficient, optional
dust collector system can be installed.
Mr. Jim Lafon, project manager of
the CPA drill program, was elated on
the success of the first installation.
“This is a momentous occasion for the
drilling division of Montabert, and it is
only the beginning,” he said.“This addition to the Montabert line of products
enhances the product offering and
speaks to the engineering innovation
that our brand prides itself on.”
“The CPA drill is effective in specialty applications like foundation, tie
back projects, slide stabilization, tunneling, tied rods, roof bolting and anchor bolting,” noted Lafon.“We have an
experienced and dedicated support
and service team that is committed to
ensuring our attachments function at
maximum capacity.”
The CPA 225E weighs in at 3,100
pounds and mounts on excavators in
the class range of 15 tons to 25 tons.
The attachment’s drilling diameter is
up to 3 inches and can drill to a depth
of 14 feet. With the addition of a 12foot rod adder it can drill to a depth
of 26 feet.
The Micro CPA II mounts on 5-ton
and larger carriers, which includes
mini excavator, backhoe loaders and
skid-steer loaders. The bit diameter
is up to 3 inches, and it can drill to a
single pass depth of 10 feet. Both the
Micro CPA & CPA 225E utilize an air
flushing compressor of 185 CFM.
For more information, visit www.
tramacbymontabert.com.
Tramac by Montabert broke new ground
in Fredricksburg, Texas, with its new
Montabert Micro CPA drill.
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19
Calendar of Events
July 2013
July 18, 2013
Great Lakes Chapter Meeting
Holiday Inn
Willowbrook, IL USA
Janet Schue, [email protected]
August 2013
August 1, 2013
Mississippi Valley Chapter’s Quarterly
Meeting
Holiday Inn, South County I-55 and Butler
Hill Road
Mehlville, MO USA
www.mvsee.org
August 11-15, 2013
23rd World Mining Conference and Expo
Montreal, Quebec, CANADA
www.wmc-expo2013.org
August 12, 2013
Jerry McDowell Scholarship Golf Outing
Norwood Hills Country Club
St. Louis, MO USA
Beverly Price, (314) 342-7589
[email protected]
August 15, 2013
Eastern PA Chapter Meeting
Lehigh Valley Iron Pigs Baseball Game
Danny Leach, (717) 574-4024
August 15, 2013
Heartland Chapter Meeting
Argosy Casino
Kansas City, MO USA
Phil Porter, [email protected]
September 2013
September 4, 2013
Blasting and Explosives Safety Training
(BEST) Seminar
South Dakota School of Mines and Crazy
Horse Memorial
Rapid City, SD USA
www.ramets.com
September 5, 2013
Potomac Chapter Meeting
Hollywood Casino - Epic Buffet
Charles Town, WV USA
Craig Mooney, (443) 695-3945
[email protected]
September 15-17, 2013
EFEE’s 7th World Conference on Explosives and Blasting Technique
Moscow, RUSSIA
www.efee.eu
September 25-27, 2013
International Symposium on Slope Stability in Open Pit Mining and Civil Engineering
Sofitel Brisbane Central Hotel
Brisbane, Australia
www.slopestability2013.com
October 2013
October 3-6, 2013
Western Canada Annual General Meeting
Kamloops, BC CANADA
www.iseewest.org
October 17, 2013
Great Lakes Chapter Meeting
Holiday Inn
Willowbrook, IL USA
Janet Schue, [email protected]
October 31, 2013
Potomac Chapter Annual Seminar
Hollywood Casino, Skyline Ball Room
Charles Town, WV USA
[email protected]
November 2013
November 7, 2013
Mississippi Valley Chapter’s Quarterly
Meeting
Holiday Inn, South County I-55 and Butler
Hill Road
Mehlville, MO USA
www.mvsee.org
November 14-15, 2013
16th Pennsylvania Drilling and Blasting
Conference
The Penn Stater Conference Center Hotel
State College, PA USA
www.outreach.psu.edu/programs/blasting
November 14, 2013
Heartland Chapter Meeting
Springfield, MO USA
Phil Porter, [email protected]
December 2013
December 6, 2013
Black Hills Chapter General Membership
Meeting
AmericInn Lodge & Suites
Rapid City, SD USA
Doug Hoy, (605) 940-1055
dough@sayreassociates
December 11-12, 2013
Kentucky Blasting Conference
Lexington Center and Hyatt Regency
Hotel
Lexington, KY USA
www.kyblastingconference.com
February 2014
February 9-12, 2014
ISEE’s 40th Annual Conference on Explosives and Blasting Technique
Denver, CO USA
Lynn Mangol, [email protected]
February 23-26, 2014
SME Annual Meeting
Salt Lake City, UT USA
www.smenet.org
March 2014
March 18-22, 2014
Conexpo-Conagg
Las Vegas, NV USA
www.conexpoconagg.com/
May 2014
May 9-15, 2014
World Tunnel Congress
Iguassu Falls, BRAZIL
www.wtc2014.com.br
May 11-14, 2014
CIM Conference and Exhibition
Vancouver Convention Center
Vancouver, BC CANADA
www.cim.org
December 2014
December 3-4, 2014
Kentucky Blasting Conference
Lexington Center and Hyatt Regency
Hotel
Lexington, KY USA
www.kyblastingconference.com
For the latest events, see ISEE’s web
site at www.isee.org
20
July/August 2013
3,216 reasons to be an
ISEE member and counting.
The ISEE Explosives Reference Database Online: Search 3,216 documents of
general and research proceedings from the Annual Conference on Explosives and
Blasting Technique, Symposia on Explosives and Blasting Research; papers from
the Journal of Explosives Engineering; RIs and ICs from the U.S. Bureau of Mines;
and the Blasters’ Catalog.
24-hours-a-day, seven-days-a-week free access for all ISEE members. All you
need is a computer and Internet access.
docs.isee.org
E X P L O S I V E S
by Robert B. Hopler
100 YEARS AGO
MORE OR LESS
As much as possible, items are reproduced as
originally printed. Misspelling and usages now
considered archaic have been retained.
A Trip Through The Anthracite Coal Mines
Jones & Evans, Publishers
Scranton News Company, Distributors
Scranton, PA
1913
22
July/August 2013
Miner boring hole. Laborer loading car.
RBH Note: in 1913 black powder was
still dominant as a coal-mining explosive, but permissible explosives were
making some slight headway. For example, in 1902 there were only 11,300
pounds of permissibles used in coal
mining, but in 1913 the quantity was
21,801,285 pounds. However, there
were 187,551,653 pounds of black
powder used that year. It took many
years before the use of black powder
ended in coal mining. From the picture
of the miner preparing his explosives
it’s hard to tell what he’s using, but the
fact that a wooden Du Pont powder
box is shown, he’s probably not using
black powder. That doesn’t mean he’s
using a permissible, either, since that
was not yet a requirement. It’s interesting that the miners have open flame
cap lamps, and the miner is actually
smoking a pipe while preparing his
explosives.
Regarding the illustrations in this
issue, the mine was in the hard-coal region of Pennsylvania, where anthracite
had been mined since the late 1700’s.
In 1913 there were hundreds of mines
in the area.This publication was a foldJuly/August 2013
Preparing powder for blast.
out set of pictures in the form of a
post card, with a spot for a stamp and
address to be entered.
Mules remained common in mines
for many more years, but I think the
employment of “Breaker Boys” was
not to go on much longer.
The photo of a miner barring down
bad roof brings back a memory from
my days in the Missouri lead mines
about just how dangerous that job is
- a young mining engineer friend of
mine was killed while attempting to
carry out just such a task.
23
100 YEARS AGO
Placing powder in the hole. Tamping column to confine.
Trip prepared for motor.
Loading coal after blast.
Approaching shaft.
Pulling car from chamber.
Dumping car for hoisting to breaker.
24
July/August 2013
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July/August 2013
25
Controlled Shaft Sinking
Using Electronic
Delay Detonators and
Water Ballast
By Francois Holowenczak, James M.W. Rickard and Greg Rappard
Somewhere in this part of Hong Kong Island is the West Island Line extension with an underground cavern station, tunnels, adits
and a few shafts. There are numerous sensitive receivers, buildings, slopes and utilities that affect the ground vibration and air overpressure limits imposed on the blasting contractor.
26
July/August 2013
Introduction
The West Island Line is one of the priority railway extensions recommended in Railway Development Strategy
2000. The West Island Line is an extension of the current
Island Line from Sheung Wan to Kennedy Town with intermediate stations at Sai Ying Pun and Hong Kong University.
Following the completion of the Detailed Design in 2009,
MTR Corporation Limited proceeded with the construction
stage of the West Island Line under various works contracts.
The contractor, Dragages Hong Kong, Maeda & Bachy
Joint Venture, was appointed by MTR to undertake the construction works of the West Island Line Works Contract No.
703 including the construction of running tunnels between
the existing Sheung Wan Station and the finger platforms
of the proposed Sai Ying Pun Station, construction shaft at
King George V Memorial Park (KGV), Sai Woo Lane shaft
and various construction adits/niches. KGV shaft is a vertical circular shaft with an internal diameter of 10 m (32.8 ft).
It is approximately 68 m (223 ft) deep, with the upper 18 m
(59 ft) in soft material and the lower 50 m (164 ft) in rock.
Originally during the detailed design stage, it was concluded that blasting was not feasible at the KGV shaft due
to the close proximity of sensitive receivers in the form of
residential buildings, electrical cables and hospitals.As a result it was planned to excavate the shaft using mechanical
means with a programme time of seven months.
A sub-contractor, Ove Arup & Partners, was employed
by the contractor to analyse whether it was feasible to blast
the KGV shaft which is the main access shaft for production works for Contract 703 on West Island Line. Originally
the contract stated that KGV shaft was to be excavated by
mechanical methods due to the close proximity of critical
sensitive receivers in relation to the shaft. But to increase
the productivity rate of shaft excavation the contractor
wanted to explore the use of explosives. To assess the feasibility of blasting the shaft, the sub-contractor conducted
an assessment involving various tools including Geographical Information System (GIS) analysis to produce a Blasting
Assessment Report (BAR) for the KGV shaft. It was concluded that if new innovative methods in blasting engineering were adopted, namely electronic delay detonators and
water ballast, it was deemed feasible to excavate the rock in
the shaft by blasting. This BAR was submitted to MTR and
the Mines Division for their approval, which they granted.
Published Geology
As indicated on the published Hong Kong Geological
Survey 1:20,000 (1989), Map Sheet 11 and described in
the Pre-Quaternary Geological Memoir (Sewell et al, 2000)
the site predominantly consists of medium grained granite
which has been described as the “Kowloon Granite” (HKGS,
2000) and has been dated to be of Jurassic-Cretaceous age.
The granite forms a sub-circular pluton centered on Kowloon and Hong Kong Island. Superficial deposits consist of
colluvium and debris flow deposits on the lower slopes of
the hillsides, especially in the Mid Levels area.
Site Geology
The site is underlain by medium grained granite designated as “Kowloon Granite” (HKGS, 2000) of the JurassicCretaceous age (typical UCS >180 MPa (26,106 psi)) and
is generally mantled with colluvium over granite, weathJuly/August 2013
ered to the consistency of soil (decomposition Grade IV or
worse) to depths typically 15 m - 30 m (49 ft – 98 ft) below
ground level.
Rockhead through the shaft varies from +18mPD
(+59ftPD) to +21mPD (69+ftPD). The average rockhead
level is +19.5mPD (+64ftPD). The shaft is generally underlain by Grade II granite. Above rockhead lies generally
a sequence of fill, colluvium and Grade V/IV granites with
corestones. One inferred N-S trending lineament is present
within the vicinity of the shaft. Corestone bearing ground
would again appear to be quite common, with rockhead
often being of an indistinct nature.
Site Constraints
The KGV shaft is located in the basketball court in King
George V Memorial Park (as shown in figure 1) in a densely populated urban area in close proximity to numerous
sensitive receivers. These range from various geotechnical
features to hospitals, and from historical and existing buildings to an assortment of old underground tunnel networks
and various utilities. Also of note was the adjacent excavation and lateral support in the form of diaphragm and
slurry walls.
Figure 1. KGV shaft location.
A summary of the Peak Particle Velocity (PPV) limits
adopted for the critical sensitive receivers (which directly
controls the maximum instantaneous charge weight), is illustrated in table 1.The frequencies of the expected vibrations were not taken into account as Hong Kong regulatory
authorities do not currently consider frequencies in their
vibration requirements.
Innovative Blasting Techniques
To combat the very restrictive PPV limits and concerns
over public exposure to air overpressure, the sub-contractor proposed combining three innovative blasting techniques never deployed before in Hong Kong; namely the
use of electronic delay detonators in shaft sinking, water
ballast and the application of Geographical Information
System (GIS) analysis to optimize the maximum instantaneous charge weight.
Electronic Detonators
Recent developments in the manufacturing process
have now made the use of electronic delay detonators an
27
Table 1. PPV limits for KGV shaft.
economically realistic option in tunnelling. Electronic delay detonators employ an electronic chip to control the
timing of the fuse-head and subsequent initiation of the
base charge. As a result, programmed timing accuracies of
±0.01% are consistently achieved. In comparison the commonly used non-electric detonators have accuracies of
±3%. This is due to the less reliable pyrotechnic delay element controlling the timing.
The main advantage of employing electronic delay detonators is the precise timing of initiation. Hong Kong blasting legislation and current best practice stipulates an 8 ms
delay between individual blasthole detonation to alleviate
the scatter issues associated with non-electric detonators.
Statistically, overlapping of blasthole detonations and superposition can occur due to the inherent scatter of nonelectric detonators, thus effectively doubling the explosive
Figure 2. Electronic delay detonators were used to ensure that the
maximum instantaneous charge
weight were not exceeded by ensuring that two holes did not fire
simultaneously within an 8 ms
window, which resulted in reduced
blast generated ground vibration
values.
28
July/August 2013
Figure 3. Spalling of water surface.
charge weights and hence increasing Peak Particle Velocities (PPVs).
Furthermore, larger, more complex blast designs can
be simplified (reducing human error during charging and
hooking up) as there can be 2,000 delays (using 5 ms delay
intervals) that are assigned programmable delay times by a
logger prior to firing, and the assigned delays and detonator
integrity can be checked electronically prior to initiation.
Increased safety devices (over-voltage, stray current, electro-magnetic pulses and static electricity), as well as software interlocks, are also incorporated to prevent accidental
initiation.
It was critical, due to the addition of water ballast, that
the electronic delay detonators employed were water proof
and that the connectors between the individual detonators
were also water-tight.The system used was also selected on
this basis.
Water Ballast
Calculations showed that even with a noise barrier, lined
with acoustic material, the air overpressure generated from
the shaft blast would exceed the 120 dBL limit employed
by the regulator in Hong Kong (the expected AOP level
at the Prince Phillip Dental Hospital was estimated at 130
dBL). Additional measures were to be employed to further
reduce any excessive air overpressure. The use of a ballasting medium, either sand or water, to cover the top of a shaft
blast to minimize air overpressure has reportedly proved to
be effective in several locations around the world and its
use is becoming increasingly acceptable as a method of reducing and controlling air overpressure levels when close
July/August 2013
to noise sensitive receivers.
The use of sand, although effective, results in additional
construction expenses of purchase, transportation and disposal for each blast and delays excavation progress due to
the time taken to place and remove the sand before and
after blasting.Additionally, sand ballast does not reduce the
level of post blast fumes as the sand does not have any natural absorbency.
Conversely the application of water ballast over the
shaft blast will absorb a large volume of post blast fumes,
can be quickly put in place prior to blasting and is easily
extracted by high capacity submersible pumps after blasting.The water ballast can be stored on-site and recycled for
each blast.
The use of water ballast in shafts as a buffer is not a
new paradigm - it has reportedly been successfully used in
other shaft sinking projects elsewhere in the world. Initially
the shock wave propagating spherically from the shallow
underwater explosion hits the water surface and reflects
as a tensile wave, or rarefaction wave. The (destructive) interference between the reflected wave and the shock front
itself causes a reduction in the amplitude of the shock
front. Spalling of the water surface occurs when the incident compressive wave and the reflected rarefaction waves
causes ejection of droplets and cavitation (or bulking) resulting in a spray dome. Ideally, the depth of the water ballast should be sufficient so that sequentially detonating
charges only result in the water ballast swelling upwards
in a periodic motion (up and down as charges detonate),
producing the spray dome.
29
Figure 4.Water Ballast in place in the shaft.
Figure 5. Pumping water out of the shaft after blasting.
30
July/August 2013
Figure 6. Excavation.
Mark Your Calendar!
Hyatt Regency Denver
at the Colorado Convention Center
Blasters Weekend
February 8-9, 2014
Reserve Your Exhibit Booth
online at www.isee.org
For more information:
International Society of Explosives Engineers
Tel: (440) 349-4400 Fax: (440) 349-3788
www.isee.org
July/August 2013
31
Figure 7. Iterative BAR approach.
Tests have demonstrated that when water is in direct
contact with detonating explosives, both the maximum
overpressure and impulse density are significantly reduced
(Eriksson, 1974; Keenan & Wager, 1992; and Eriksson &
Vretblad, 1994). This reduction has been attributed to the
loss of energy from the shock into breaking up the water
into droplets. Therefore it was recommended that 1.5 m
(4.9 ft) – later reduced to 0.8 m (2.6 ft) – of water ballast
(gross weight of circa 118 tonne (132 ton)) be employed
for the shaft blasting.
GIS Modelling
The sub-contractor have developed a unique in-house
GIS modelling tool that enables ‘rapid development of the
optimised charge weights and identification of controlling
sensitive receivers surrounding the blast’ (Chuang et al,
2009).The customised ‘Add Ins’ make use of the 3D Analyst
extension in the ArcGIS software that allows different spatial layers (e.g. tunnel alignments, buildings, ground surface
contours) to be added to the model. The iterative Blasting
Assessment Report (BAR) approach used is illustrated in
figure 7.
Due to the amount of surface and sub-surface data that
is now readily available in Hong Kong tunnelling projects
the GIS platform is also a useful interface to graphically
display the large spatial data sets. GIS streamlines the workflow, reduces staff resources (resulting in 20 times quicker
iteration time) and more importantly, from a client’s perspective, responds quickly to ever changing design requirements on site by producing accurate charge weights
reflecting the complex ground conditions and numerous
sensitive receivers.
32
Combined Methodology for KGV Shaft
The first step in undertaking blasting in Hong Kong is
to seek approval of a BAR by the Geotechnical Engineering Office and Mines Division – the regulatory government
authorities – who determine whether the engineer to contract has demonstrated that blasting works can be conducted safely (limiting ground vibration of sensitive receivers)
and with minimal impact to the public, communities and
other stakeholders. A comprehensive assessment of sensitive receivers and the application of relevant mitigation
measures must be clearly demonstrated.
GIS Approach for KGV
Initially a GIS model was constructed importing all the
relevant spatial layers in order to provide an accurate terrain picture. Working drawings of the KGV shaft including
the excavation and lateral support were added and rockhead contours also rendered.
The next step involved segregating the shaft into layers representing probable pull depths and optimizing the
charge weights at each level using the iterative approach
in figure 7. Predicted PPV and air overpressure contours
were calculated to clearly illustrate the impact that the proposed blasting had on nearby sensitive receivers, based on
Li & Ng (1992) ground attenuation constants K = 644 and
B = 1.22 and using equation 1.
Equation 1.
July/August 2013
Figure 8. PPV contours.
This model could be calibrated once sufficient monitoring data had been collected in order to determine the new
site-specific constants.
PPV Analysis
Peak particle velocity (PPV) contour plots were produced for the area where blasting is proposed. These plots
were produced in two sets; the first set to indicate the PPV
that would be received at the ground surface when the
blast charge weight is calculated using all sensitive receivers except slopes and subject to a maximum 5 kg (11 lb)
per delay charge weight.
The second set of contours
showed the PPV received at
the surface when the blast
charge weight was calculated
using all sensitive receivers
including all slopes and retaining walls. The 5 mm/s (0.2
in/s), 13 mm/s (0.5 in/s) and
25 mm/s (0.98 in/s) contours
were shown at ground surface
for this set of contours.
An iterative process was
used to arrive at the final version of the second set of contours, after production of the
critical structures and utilities
contour line, by selecting relevant slopes and retaining walls
for analysis of the maximum
allowable PPV.
July/August 2013
The calculated maximum allowable PPVs for these
analyzed features were then added into the calculation of
the maximum allowable charge weight and a new set of
all sensitive receivers contours was produced. If there remained features inside the 5 mm/s (0.2 in/s) all sensitive
receiver contour that had not been analysed, the process
was repeated until all slopes and retaining walls within the
5 mm/s (0.2 in/s) all sensitive receiver contour had been
analyzed.
33
Table 2. Initial and final blast design parameters.
Blast Design
The 10 m (32.8 ft) diameter shaft, resulting in a 78.5 m2
(845 in2) surface area for blasting, required rock blasting
over a depth of 37 m (121.4 ft). It should be noted that
nine 600 mm (23.6 in) diameter holes were bored along
the center line of the shaft.These were originally drilled to
aid the mechanical excavation initially proposed, but were
then used as relief holes for the blasting works. Using three
shotfirers and three trainee shotfirers, blasting was conducted once to twice a week. Initially it took eight hours
to load the shot but this was later reduced to five hours as
changes to the blast parameters were made. A total of 24
blasts were required to complete the shaft excavation.The
initial blast design was improved as the project progressed
resulting in some efficiency gains as seen in table 2.
Pull depths of 1 m - 2 m (3.3 ft - 6.6 ft) were initially designed with 410 blastholes including perimeter and cushion holes to avoid overbreak. The initial timing design was
for inter-hole delays of 5 ms and inter-row delays of 10 ms.
This was later changed to 5 ms and 20 ms respectively due
to concerns with desensitization of emulsion cartridges
and shrink-wrapping of the detonators. For the same reason it was also decided to increase the burden and spacing
to 0.6 m x 0.6 m (2 ft x 2 ft).
The sub-contractor opted to use the SmartShot™ electronic delay detonator system to initiate the blasts. This
system makes use of a Harwin connector to connect adjacent units, which, when properly connected, eliminates the
possibility of leakage occurring on the system, allowing for
successful operation in up to 3 bar (43.5 psi) of water pressure. Due to the water ballast that was proposed, it was essential to use a connector with excellent water resistance
that could handle the high operating pressures.
34
Figure 9. Example of electronic delay detonator hook-up.
Results and Successes
Legislative approval of the BAR for the KGV shaft was
granted after numerous consultations with the government
authorities and the community, and blasting operations
started on Aug. 4, 2010, and ceased on Oct. 23, 2010.
Prior to blasting, strict PPV and air overpressure limits
were agreed. In total 24 blasts were fired with average pulls
of 1.6 m (5.25 ft). PPVs rarely exceeded 2 in/s - 3 mm/s
July/August 2013
Figure 10. Great public relations.
(0.08 in/s - 0.12 in/s) at a distance of 30 m - 40 m (98 ft 131 ft) from the blast location. AOP levels recorded at the
Prince Phillip Dental Hospital at a radial distance of 42 m
- 66 m (138 ft - 217 ft) from the blast face were in the range
of 116 dBL - 119 dBL, below the Hong Kong target level
of 120 dBL. Without the water ballast the AOP level at the
Prince Phillip Dental Hospital would be expected to have
regularly exceeded the target level, causing intervention by
the regulator and suspension of the program.
References
Project successes can be summarized as:
• Successful application of GIS analysis and modelling to
optimize charge weights.
• The use of water ballast as an effective key additional
mitigation measure against air overpressure (a steel shaft
cover and a noise enclosure were the primary mitigation
measures).
• Employmentofwaterproofelectronicdelaydetonators
to allow the use of water ballast, effectively reducing
PPVs by almost 40%.
• Programreductionbythreemonths.
• HK$5millionsavingindirectcosts.
• No major concerns received from the public or other
stakeholders.
• Greatpublicrelationsshowcase–blastingwassoquiet
evenTaiChiclassescouldstillgoahead!
Keenan,W.A.andWager,P.C.(1992),“MitigationofConfinedExplosionEffectsbyPlacingWaterinProximityofExplosions”,25thDoD
ExplosivesSafetySeminar,Anaheim,CL.
Chuang,A.T.C.,Wallace,M.I.andLau,V.S.Y.(2009),Developmentofa
GISbasedanalysistoolfortunnelblastinganditseffectsonnearby
sensitivereceivers.HongKongTunnellingConference2009,Hong
Kong,pp125-134.
Eriksson,S.(1974),“WaterinExplosivesStorage”,FortF/FReportC
104,Stockholm.
Eriksson, S. andVretblad, B. (1994),“Blast Mitigation in Confined
SpacesbyEnergyAbsorbingMaterials”,26thDDESBSeminar,Miami,
FL,16-18August1994.
Hong Kong Geological Survey Maps 1:20,000 Map Sheets: Digital
Set.
Li,U.K.andNg,S.Y.(1992),“Predictionofblastvibrationandcurrent
practiceofmeasurementinHongKong”,ProceedingsoftheConference‘AsiaPacific-QuarryingtheRim’,HongKong,pp119-135.
Richards,A.B. (2008),“Prediction and Control ofAir Overpressure
from Blasting in Hong Kong”, GEO Report No. 232, Geotechnical
EngineeringOffice,46p.
Sewell,R.J.,Campbell,S.D.G.,Fletcher,C.J.N.,Lai,K.W.andKirk,P.A.
(2000),“ThePre-QuaternaryGeologyofHongKong”.
Young,G.A.(1973),“PlumeandEjectaHazardsfromUnderwaterExplosions”,USNavalOrdnanceLaboratory,WhiteOak,SilverSpring,
Md.,NOLTR73-111.
Theinnovativemethodsadoptedandprojectsuccesses
reduced the excavation program by three months, saved
HK$5millionindirectcostsandkepttheimpactsonthe
publicandotherstakeholdersnearbytheKGVShafttoa
minimum. Due to the successful implementation of the
blastingattheKGVshaft,theSaiWooLaneshaftwasexcavated employing similar techniques and was also completed successfully.
This article was presented by the authors at ISEE’s 39th Annual
Conference on Explosives and Blasting Technique in February,
2013 in Fort Worth, Texas. This paper has been updated from its
original version. The opinions and ideas expressed are not necessarily those of the International Society of Explosives Engineers
or the editorial/publishing staff of the Journal of Explosives
Engineering. See “The Proceedings of the 39th Annual Conference
Acknowledgements
on Explosives and Blasting Technique” for full text and references
The authors wish to thank the management of MTR Corporation for this paper.
Limited, not only for its permission to publish the information in
thisarticle,butalsofortakingaproactiveleadindrivingtheuseof
blasting and electronic delay detonators for this project.
July/August 2013
35
20th
20th Annual
Photo Contest
Honorable Mention
WAC Bennett Dam
Category: Specialty Blasting
Submitted by: Corry Goumans
Blaster in Charge: Byron Groen
Photographer: Corry Goumans
Description of Project:
Project location is at WAC Bennett Dam
in Hudson’s Hope, British Columbia,
Canada.
Photo 2. The drill crews are drilling from 5 feet to 20 feet into the
rock on a 6 foot grid pattern with the bit size at 2.5 inch hole
inserting 1 inch anchor 5 feet to 20 feet long rock bolt that is
fully grouted.
Photo 1. The crew of four drillers on our drill platform tied onto
a crane over 150 feet over the dam spill way plus 400 feet to the
river. Drilling is done with one Ingersoll liner drill and one Joy
bencher drill.
Photo 3. Crew’s gun-ite the entire rock face.
36
July/August 2013
21st Annual
Photo Contest
Official Entry Form
WAC Bennett Dam in Hudson’s Hope, BC, Canada
Photo by Corry Goumans
Give Us Your Best Shot!
Rules of Entry
A. Entries must be submitted on photographic paper, no larger
than 8 x 10 inches (20.32 x 25.4 cm), along with high resolution
JPGs. Photos with excessive commercialism (company logos,
etc.) will not be accepted. Do not superimpose company logos
into photographs.
B. Entries must include an official entry form, a description of
the project on a separate sheet of paper and a signature of the
photographer.
C. The International Society of Explosives Engineers is granted
unlimited use of all photo entries. Photos may be used in full or
in part in all ISEE publications and marketing materials, without compensation. Entries will not be returned and become the
property of the Society of Explosives Engineers, Inc.
D. Qualifying entries may be displayed at the 40th annual
conference in Denver, Colo., USA.Winning entries may be
displayed in the Journal of Explosives Engineering.
E. Entries will not be accepted on site.You must submit your
entry, along with a completed entry form, by Dec. 20, 2013.
F. Submit entries to: ISEE Photo Contest, 30325 Bainbridge
Road, Cleveland, OH 44139. No entry fee is required. For
more information, contact the photo contest coordinator, (440)
349-4400, or e-mail [email protected].
21st Annual Photo Contest Official Entry Form
Submitted by:
Name:______________________________________________________
Company:___________________________________________________
Addres:_____________________________________________________
City:______________________________State:_____________________
Country:_________________________ Postal Code:_________________
Tel:____________________________E-mail:_______________________
Photographer:_______________________________________________
(Signature of photographer is required. Use one form per photographer.)
Detailed Description of Project(s): (include in a separate file)
Categories of Entry
1. Blasters and Drillers at Work (People Photos)
a) Individual Photo or, b) Series of Photos (Limit of 5 photos)
2. Construction Blasting
3. Quarrying and Mining
4. Demolition Blasting
5. Specialty Blasting
Avalanche control, special effects, or extreme locations.
6. Artistic Photo Alteration
Photos that have been digitally enhanced with artistic filters.
(Limit of 5 photos)
Judging
Entries will be judged on quality, composition, and content.
Photos must depict safe operations to qualify. Entries will be
judged at the 40th annual conference in Denver, Colo.
Award
One $500 gift certificate to ISEE will be awarded to the entry
voted Best in Show.
Entries (use a different form for each photographer)
1. Category of Entry:_________ Entry Name:_______________________
Blaster in charge: _____________________________________________
2. Category of Entry:_________ Entry Name:______________________
I ___________________________________(Signature of photographer)
have read and accept the rules of entry.
International Society of Explosives Engineers • 30325 Bainbridge Road • Cleveland, OH 44139 • www.isee.org
Deadline for Entries: December 6, 2013
Display Advertising Index
AAMCOR .............................................................25
AGA .....................................................................25
Apache Construction Corp..................................19
Austin Powder ................................................. OBC
Booster Lock........................................................13
Dyno Nobel ....................................................... IFC
Focus Mining .......................................................16
Instantel .............................................................. 11
ISEE Conference ..................................................31
ISEE Online Database ..........................................21
ISEE Photo Contest ..............................................37
MREL ...................................................................13
Nobel Insurance ....................................................1
Reliable Tire .........................................................19
Rockmore ..............................................................4
Tread Corporation .................................................9
Vibronics ...............................................................5
White Industrial Seismology..................................3
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Maine Drilling & Blasting, a leader in the
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This series was originally introduced in The Journal of
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July/August 2013
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March/April 2008
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