1. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
EFEE made the basic training manual for Rock blasting education in 2004.
The ESSEEM project was carried out through the years 2008 – 2010.
NFF (Norwegian Tunneling Society) was the contractor.
The project had partners from 6 European countries.

2. European Shotfirer Standard Education for Enhanced Mobility
Frank
Hammelmann
Jörg
Rennert
Erik
Nilsson
Juoko
Salonen
Aslak
Ravlo
European Shotfirer Standard
Education for Enhanced Mobility
– ESSEEM –
Ferjencik
Milos
Walter
Werner
Jose Carlos
Gois
Karl
Kure
Antonio
Vieira

3. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The training material prepared by the ESSEEM project included about 1300 slides and images. The level was to high to be used for the education of shotfirers. A Norwegian/Swedish group has evaluated the slides and images, and has reduced the content. The new version of the ESSEEM slides and images program was presented in the EFEE-workshop in Zandvoort at the end of April 2013.

4. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
NFF working group: 11 experienced blasters and blast designers, contractors and advisers
NFF : Jan Kristiansen Karl Kure
Amund Bruland Bjørn Petterson
Aslak Ravlo Hans Christen Evensen
Vegard Olsen Thor Andersen
Olav Fjellstad John Eriksen
BEF : Jan Johansson,

5. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The Working Group has taken into account the comments provided by participants in the workshop and presents herewith an edited version of the training material. There will still be some chapters that could better suit the educational requirements for the education of a modern European blaster. However, this must be presented in future revised versions. This version is now free to be used for the EFEE members who wants to translate the training means to the national language August 2013 NFF, Norwegian EFEE, Shotfiring Tunneling Society Comittee

6. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Copyright Notice
The pages and documents developed during the ESSEEM project are subject to copyright .Unless you have prior written permission from European Federation of Explosives Engineers (EFEE), no part of these pages and documents may be reproduced, stored or transmitted in any form or by any means to a third party. You are granted the right to use the material received and making copies for private use only. This right does not grant you, or any person, the right to include any of the materials in a published work without prior written permission from EFEE.

7. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Disclaimer
Please note that the information developed in the ESSEEM project is of a general nature and is intended to be a guideline for the course leading to an EFEE rock blasting certificate. Professional advice should be taken before any course of action is pursued. The information presented here is offered free of charge and, accordingly, EFEE takes no responsibility for any loss occasioned by the use of the information presented here for whatever reason. .

8. Blasting close to existing structures Author : Karl Kure, Norway
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
ESSEEM project WP 9 :
Blasting close to existing structures
Author : Karl Kure, Norway

9. Course planning Time (5 hours)
Blasting parameters min
Different reasons for blasting damage 90 min
Flyrock min
The use of blasting mats min
Line drilling and blasting min
Charge calculation, initiation plan min

10. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The problems by blasting close to existing structures are in this lecture described :
by means of practical examples taken from projects where blasting damage has occurred.
by showing practical methods from difficult projects where blasting has been carried through without damage. 10

11. SMAL HOLES BIG HOLES Borgang 11 og 12 2” 34 to 40 mm 51 mm

12. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The risk for blasting damage in build-up areas depends very much on :
- the distance from the blast round to the structure
- the size of the charges detonating at each time interval
Different borehole diameters are in use, however close to a building only small boreholes should be used. 12

13. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
By the use of small charges, which often has to be divided into different decks, the cartridges mostly have a diameter from 22 to 40 mm. The bore hole diameter suited for this cartridges are 1” to 2” inch (25 to 51 mm).
Large charges in bore holes with diameter bigger than 2 ½ “ (64 mm) should only be used by distances from the blast round to the building above 20 m. 13

14. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
In most European countries hundreds of blast rounds are fired every day.
In the nordic countries we can hardly not build a flat, a one family house, a short piece of road or railroad without blasting.
A few of this hundreds of blast rounds tend to go wrong.
We will show you some damage examples and discuss the reason for the damage. 14

15. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Experience
The following pictures and drawings from real worst cases have been selected from records covering the last 3 decades. These are instructive examples for the type of damage that may occur during a blasting operation.
The distances from the blast rounds to the structures are different. The size of the charges and the diameter of the boreholes are also different from case to case. 15

16. Different reasons for blasting damage :
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Different reasons for blasting damage :
Type 2.1 :
When the charges brake into the structure (close by).
Type 2.2 :
When the rock mass moves towards the structure (a distance of some meters).
Type2.3 :
When an overloaded blast round is thrown towards the structure (a distance of some meters).
Type 2.4 :
When pieces of flyrock are thrown and hit human beings and structures (by construction blasting up to a distance of some hundreds meters).

17. Type 2.1 When the charges breack into the structure (close by).
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.1 When the charges breack into
the structure (close by). 17 17

18. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.2 When the rock mass moves
towards the structure
(at a distance of some meters) 18

19. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.3 When an overloaded blast round
is thrown towards the structure
(at a distance of some meters). 19 19

20. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown towards
a sports hall
Flyrock was thrown across the road and over a school building towards the Grimstad sports hall where a person sitting in a car was hit and instantly killed.
The stone weighed 2.9 kg.

21. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.1 When the charges break into the nearby structure (very close by the blast round).
This may happen :
by using small charges (cartridges up to 30 mm) when the distances are between 0 and 1 m.
b) By using largeer charges (artridges up to 40 mm)
when the distances are up to 3 m.
Example 1 : New warehouse
Example 2 : Trenching close to a wall 21

22. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type Example 1 : New warehouse 22

23. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type Example 1 : New warehouse
A new warehouse close to an existing building was planned.
The base was to be one floor deeper than the existing building.
The excavation of the earth before the blast left the foundation under one corner of the existing building “hanging in the air”
and it had to be supported.
The corner of the wall was not jacked up. The stress was not released by this support. 23

24. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.1, Example 1 :
New warehouse
The rock was layered at the site.
The joints run from the blast round in under the floor of the existing building.
Holes were drilled and some grouted bolts were installed.
A row of contour holes (60 cm spacing) was drilled and blasted together with the normal blast holes in the same blast round.

25. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
New warehouse.
Layered rock. The charges broke in under the structure and lifted it up. 25

26. Type 2.1 Example 1, New warehouse
Cut through the rock and the existing house showing the situation before the last blastround
Brickwork
Rock bolting
wood
Concrete
Concrete wall
Charge
Explosive gases

27. In the last blast round only a row of contour charges were blasted
In the last blast round only a row of contour charges were blasted. The contour tube charge was about 0,3 kg gurit in each hole, initiated on one detonator time interval. The distance from the charge to the concrete wall was 1 m. Vibration : √Q √0, v = k = = 192 mm/s d ,0 The concrete wall was exposed for high vibration in addition to the explosive gas pressure into the rock through the cracks under the building.

28. The crack in the outside brick wall was 7 cm wide.
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
New warehouse.
The crack in the outside brick wall was 7 cm wide.

29. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
New warehouse.
The reinforced concrete foundation had about 10 new vertical cracks

30. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the damage :
The vertical stress in the foundation was not released before
the blast round was fired.
2) There was inadequate rock bolting.
3) The charge size was too large.
4) The gas pressure penetrated the rock under the building and lifted it up .

31. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.1, Example 2 :
Trenching close to a wall
The building was founded directly on the rock ground just a few cm
beneath the outside surface ground level.
The rock at the site is horizontally layered.
A narrow 1.5 m deep drainage trench had to be blasted outside
the wall all the way around the building.
The line drilling method was not used, no contour holes were drilled and no special measures were taken to prevent backbreak under the basement wall.
Normal trench blasting methodes were wrongly used not taking into accont the short distances to the basement wall.

32. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Trenching close to a wall.
The basment wall was pressed in and damaged from the trench blasting all the way around. 32

33. 020114-2 Trenching close to a wall.
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Trenching close to a wall.
The were a lot of cracks in the basement wall on all sides (srrovs).

34. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Trenching close to a wall.
The crack in the unreinforced basement wall ran from the top to the bottom of the wall.

35. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the damage :
1) The blast holes were drilled to close to the wall.
2) No gas evacuation holes were drilled (no line drilling).
3) The gas pressure followed the horizontal cracks under the building and lifted it up. 35

36. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type When the rock mass moves towards the structure (at a distance of some metres).
This may happen when:
a) using small chargesthe distances are less than 5 m
b) using large chargesthe distances are less than 10 m
Example 1 : Rock movement due to trenching
Example 2 : Rock movement as a result of heavy
confinement by quarry blasting

37. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement due to trenching
The trench was located in the middle of the road (left side in the picture) 37

38. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type Example 1:
Rock movement by trenching
A very deep trench (6 m) had to be blasted about 8 m from a family
house founded on rock ground. The pit for the basement of the
existing house, when it was built, was blasted down into the rock.
The bedding in the rock mass runs directly from the blast round
situated in the road to the house.
The blast round was extremely heavily loaded.
No special efforts were made to prevent the explosive force from
moving the rock in the direction of the house. 38

39. O00224-2 Rock movment by trenching
The rock was layered

40. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement due to trenching
As a result of the blasting in a 5 m deep trench, the rock mass moved 8 m towards the nearby house.
BEDDED ROCK
 m 
Cracks in the basement wall
Frozen clayey soil
Road cut
Rock displaced by the blast
Stemming
Charge
Bedding

41. 000224-1 Rock movement due to trenching7 5 6 4 3
crack 1 2
8 m
house
Burden and spacing : 1,3 x 1,5 m, depth : 5 m

42. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement due to trenching
The detonation pressure moved the rock mass 8 m and caused a vertical crack in the wall at the corner . 42

43. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement due to trenching
The movement of the rock mass caused horizontal cracks in the basement wall.

44. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the damage :
1) 5 m deep drill holes are too deep for a blast round in a trench so close to the house. Because of the depth the trench should have been divided into two parts, by blasting 2,5 m deep each blast round. The borhole diameter was 2” (51 mm).
The charges had to be extremely heavy (Dynamite,
40 x 400 mm and ANFO) to break and move the rock forward in such a deep trench. The powder factor (inside the hole rows) was 1,57 kg/cbm, twice as much as necessarry by shallow trenches in layered rock .
3) The soil at the surface was frozen, the rock was bedded This favored the movement of the rock mass towards the house.

45. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.2, Example 2 : Rock movement as
a result of heavy confinement by quarry
blasting
A large blast round had to be blasted in a quarry, about 15 m from a storage hall. The distance from the blast round to the rock wall was only m.
The blast round was on average 12.5 m deep, and was drilled using a 3 1/2” (88 mm) diameter drill bit. The holes were loaded using emulsion slurries.
The sloped bedding in the rock mass runs directly from the blast round to the rock wall close to the storage hall.

46. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement as a result
of quarry blasting
The m thick rock mass moved as a result of the pressure from the round against a storage hall.
Section A - A
Distance
10-12 m
Level
40 m
Level
35 m
Unloaded 5m
Level
30 m
Level
Approx.
27 m
Storage hall
Bulk Emulsion Explosive
Rock, gravel

47. 980201-4 Rock movement as a result of quarry blasting
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement as a result of quarry blasting
The blast round included about 100 loaded holes. The detonation
started in the centre of the wide V. This resulted in an enormous
pressure against the rock mass along the hall.
Section A
Level 40m
Level 35m
Distance to the charge approx. 15m
Level 30m
Storage hall 47

48. 980102- 2 Rock movement as a result of quarry blasting
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement as a result of quarry blasting
The bedding in the rock ran from the round in the direction of the storage
hall. Resistance against the pressure from the large round was low. The
upper part of the rock mass moved towards the hall. 48

49. 980201-3 Rock movement as a result of quarry blasting
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement as a result of quarry blasting
The bedding planes, running from the blast round towards the hall
are smooth. The resistance against movement along the planes is low.

50. 980201-5 Rock movement as a result of quarry blasting.
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement as a result of quarry blasting.
Large parts of the wooden hall construction and the corrugated sheets were destroyed (already partly replaced).

51. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Rock movement as a result of quarry blasting.
Flyrock destroyed the roof.

52. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the damage :
The time intervals, 25 ms between the rows and 17 ms inside the rows, were generally too short for such a big blast round (100 holes) formed like a wide V by such a short distance through the rock to the hall.
2) The V-shape of the blast round and the order of the time intervals resulted in an enormous pressure from the detonating charges backwards against the rock in
the back wall close to the hall.
3) The direction of the cracks in the bedding plane gave very low resistance against the movement of the rock mass backwards against the building.

53. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.3 : When an overloaded blast round is thrown towards the structure
This may happen when :
a) using small chargesthe distances are from 0 to 10 m
b) using large chargesthe distances are from 0 to 20 m
Example 1 : Blasting close to a wharfside shed
Example 2 : Blasting for a garage foundation

54. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.3 Example 1 :
Blasting close to a wharfside
shed
A pit for the foundations of a new workshop were to be blasted out about 10 m from the existing warehouse lying directly on the wharf.
The rock at the site was solid.
The icescoured rock surface in the blast area fell at an angle about 30 degrees towards the wharfside shed.
The blast round was overloaded.

55. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to a
wharfside shed
The left-hand part of the building along the wharf was destroyed by the blast round at the back of the warehouse.

56. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to a
wharfside shed
About 20 tons of fragmented rock and rubber mats were thrown against and onto the warehouse.

57. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to a
wharf/warehouse
The wooden strip indicates where the rock surface was before the blast was fired ( the workshop was built after the blasting work was carried through).

58. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to a
wharfside shed/warehouse
The destruction inside was enormous.

59. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to a
wharfside shed/warehouse
Horizontal pressure moved the landing . The concrete columns under the landing were broken horizontally.

60. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the damage :
1) The rock surface was smooth, nowhere an open faces as front for the first blast round.
2) To get an opening in the rock mass the powder factor generally had to be high, but here it was overloaded.
3) The blastability of the rock type at the site (gneiss) is evaluated to be poor.
4) For a trial blast, the blast round generally was too big A small opening blast round should have been blasted out first to establish a vertical front for the next blast round.

61. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.3 Example 2 :
Garage foundation
A pit for the foundation of a garage had to be blasted out close to the family house.The house was founded directly upon the rock surface.
The rock surface and the bedding fell towards the house. There were also some nearly vertical cracks running from the blast round in the direction to the house.
The blast round was overloaded. The powder factor was too high.
The house was totally destroyed by the blast and had to be
torn down.

62. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Garage foundation
The fragmented rock mass was thrown against the house nearby. A

63. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Garage foundation
Layered and jointed limestone rock.

64. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Garage foundation
The house was displaced 27 cm, measured at the corner nearest to the blast round.

65. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Garage foundation
The fragmented rock broke through the wall into the stairway.

66. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Garage foundation
The chimney was badly damaged.

67. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the damage :
1. The opening blast round was too big.
2. The holes were too heavily charged
for the dense borehole pattern.
3. The blast round was completely over-loaded,
the powder factor was in average 0,77 kg/cbm,
0,81 in the first row.
4. Some vertical cracks in the rock mass ran straight
from the bore holes in the direction to the house
redused the resistance against through of the mass.

68. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Possible damage :
Type 2.4 : When flyrock is thrown towards
human beings and buildings.
This may happen when :
a) using small chargesthe distances are up to 500 m
b) using large charges the distances are up to 1000 m
Example 1: Flyrock thrown towards a sports hall
Example 2: Flyrock thrown into a parking area

69. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock killed a person by a sports hall.
An industrial area for a new building had to be blasted out. The blasting work was almost finished when an accident occured.
Relatively close by the blast round ( about 100 m) there were a nursery school, a secondary school and m further a sports hall.
The rock mass in the blast round was in the range of 5000 cub.m. The rock mass at the site was jointed. Boulders also had to be blasted in the same blast round.

70. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock killed a person by a sports hall.
A spray of flyrock flew over the school building (right in the picture) towards the sports hall (arrow).

71. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown towards
a sports hall
Flyrock was thrown across the road and over a school building towards the Grimstad sports hall where a person sitting in a car was hit and instantly killed.
The stone weighed 2.9 kg.

72. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown towards a
sports hall
Cut through the blast round and the loaded boulders. The boulders were also blasted in the same blast round.
Stemming 2 m
Stemming first row m
Throw
direction
2.5” drill holes
1.8 X 2.3 m
pattern
7.0 m
Stone
5 m
Stone
5 m3
Blasted rock material
Row
Sub-drilling 1m

73. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock killed a person by a sports hall.
Many blast rounds had been fired ahead of the catastrophic blast round.
Some small flying pieces of rock had from two blast rounds had landed on the flat roof of the nearby secondary school. No damage had occurred so far, but no-one in the site office seemed to take the warning and see that this could mean a big danger for flyrock.
About 5 big boulders (pop-hole shooting with 2 ½” holes and 50 mm dynamite cartridges) was also fired together with the big blast round.
A picture taken from the bench before the blast round was fired shows that there a weakness zone running through the front of the bench.
The piece of flyrock that killed a person in a car by the sports hall, flew 432 m through the air, hit the asphalt and ricocheted off into the car window and hit a person sitting there.

74. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type When pieces of flyrock are thrown
towards human beings, animals
and structures (at a few to some
hundred meters distance)
The balistic curve of the stone
branch
Ca. 40 degrees
Person in a car
asphalt
asphalt 74 74

75. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown towards a
sports hall
A crushed zone in the rock mass at the front of the blast round (yellow circle) marks the area where the unlucky piece of flyrock presumably came from. O

76. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the flyrock :
A 5000 cub.m. blast round is too big to monitor for flyrock and
to cover with blasting mats in a build up area.
The distances to the public buildings in the surroundings were
too short to be ignored with regard to the risk for flyrock.
The unlucky piece of flyrock might presumably (80%) have come
from the weakness zone in the bench front. It could however (maybe
less than 20 % plausible) have come from one of the 5 big boulders
that was blasted together with the bench. This was never clarified.

77. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.4 Example 2 : Flyrock thrown into a parking area A
The sixth blast round in a road cut, was drilled and loaded. By the first firing of the blast round only the contour charges detonated (detonators failed). Because of the high vibration level (the contour charges did bot brake through) a small part of the vertically jointed rock in the front of the blast round fell out. The burden in the first row was by this reduced.
By the second firing, large pieces of flyrock were thrown towards the nearby shopping centre and the parking area. A member of the blasting crew (guard) was killed by a heavy stone (about 200 kg).
The stone flew about 80 m foreward through the air from the front of the blast round.

78. 030226-1 Flyrock thrown into a parking area - drawing 1
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown into a parking area - drawing 1
The distance from the blast round to the parking area by the shopping centre was definitly to short.
Planned road cut
Blast round
no. 6
Distance to parking area
80 m

79. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Type 2.4 Example 2 : Flyrock thrown
into a parking area
The diameter of the boreholes was 70 mm. The holes were loaded using ANFO and dynamite.
The initiating system was non-electric detonators in combination with surface delays. The ranking of the delay numbers was like normal for this type of blasting work.
The distance from the blast round to the parking area was very short in relationship to the accepted danger distances for flyrock.

80. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown onto a parking area
Picture taken after the first insufficient blast. There are som rubber mats lying at the front of the bench. These mats fell down together with some layers of rock during the first blast.

81. 030226-3 Flyrock thrown into a parking area
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown into a parking area
The blast round was covered by rubber mats the second time by the second blast round at the same bench.

82. 030226-4 Flyrock thrown into a parking area
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown into a parking area
The explosives in the blast round is detonating. Flyrock can be seen in the front of the blasting fumes . At least two of the detonating charges “are blowing up the stemming” and the mats are lifted up into the air.

83. 030226-5 Flyrock thrown into a parking area
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown into a parking area
An overview picture of the same area as photo 1 and 2. The muck pile from the blast round is not thrown further forwards than normal by bench blasting in a road cut.
Does the blast round seem to be overloaded ?

84. 030226-6 Flyrock thrown into a parking area. Drawing 2
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Flyrock thrown into a parking area. Drawing 2
Outfall from the first misfire
Over-loaded area from the second blast
FLYROCK

85. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The reasons for the flyrock :
1) The main reason for the catastrophic flyrock was found to be
an undetected thin burden in the first row due to rock fall
caused by vibration from the first unsuccessful blast.
2) The misfire of the first blast was caused by destruction of the
NONEL tubes. (An excavator belted out on the covering mats
after the coupling of the tubes).
3) I n the case, the shotfirer, the blasting contractor, the main
contractor and the client were all found guilty and sentenced
through legal proceedings.

86. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
3.0 Main reasons for flyrock
The blast round is overloaded
The blast round is underloaded
The stemming is not sufficient
Borehole deviation, inaccurate pattern
Irregular bench front
Unforeseen rock weakness in the front
Unfavourable firing plan (short/long time intervals)
Breaks/caverns filled with explosive

87. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
3.0 Why does the risk exist in the examples used ?
For discussion :
3.1 Is the reason for the damage that the distance
from the charge to the structure is too short ?
3.2 Is the reason for the damage that the strength
of the rock mass is too low ?
3.3 Is the main reason for the damage that
excessively high powder factors are used ?
3.4 What are the reasons for the damage by flyrock?
Is it due to poor drilling, loading, mat covering, etc ?

88. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
4.0 What should you look for when planning a blast round close to structures ?
For discussion :
4.1 Look for the strength of the structure and the
quality of the rock.
4.2 Are there joints, cracks or layered rock in the
rock mass?
4.3 Calculation of the charges, powder factor and
initiation plan.
4.4 Besides of direct movement of the rock mass,
watch out for flyrock being thrown towards
human beings, animals and structures.

89. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to structures
Main differences from free blasting :
Backbreak into or under the structure can not
be accepted.
The level of the vibration has to be controlled
at the structure foundation.
Low (but not too low) powder factor and reduced
throw of the rock masses has to be accepted.
The blast round has to be covered by heavy,
flexible rubber mats.

90. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to a construction
By blasting direct outside a construction, the rock mass or fragmented rock may move into the construction if you do not include measures to prevent this.
House
Planned 
excavation

91. Blasting close to a construction
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Blasting close to a construction
The non-problematc part of the rock mass must be blasted out first.
The house wall mest be digged free before the blast.
The gravel has to be removed
This part has to be blasted out first
House

92. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Covering of blast rounds with
rubber mats :
Rubber mats must be made from strong and tough materials, like lorry tyres and coarse steel wires.

93. Covering of blast rounds with rubber mats :
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Covering of blast rounds with
rubber mats :
Before the rubber mat covering can be placed over the charged blast round, everything has to be checked :
The front of the blast round has to be covered by coarse material sorted out from the last muck pile. The stone covering in the front must be filled higher than the height of the bottom charge.
The length of the stemming must at
least be as long as the burden.
In the first row the stemming
should be a bit longer.
burden
burden
stemming
> burden
Coarse fragmented rock
Bottom charge
1.3 x burden

94. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Bench blasting :
The most dangerous flyrock will come
From the upper part of the bench front.
chains
mats
bolt
blasting
rubber
heavy

95. high specific charge that means : heavy covering will be needed
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Trench blasting :
high specific charge that means :
heavy covering will be needed
chains
2-3 layers of heavy rubber mats
bolt
Loaded boreholes
Holes not in use in this blast round

96. The rubber mats must together act as a single sheet.
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The rubber mats must together act as a single sheet.
It is necessary to connect the mats.
It is practical to use chain slings to connect the rubber mats.

97. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The following pictures will show on the hand of examples how blast rounds can be covered by using rubber blasting mats.

98. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
010305, The drilling of blast round
nr. 3 is finished.
Example 1, picture 1

99. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
010305, Blast round nr. 3 has been loaded
and covered by mats. Chain slings
hold the mats together.
Chain slings
Example 1, picture 2

100. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
010305, Blast round nr. 3 after the blast.
The mats have held the
fragmented rock together well.
Example 1, picture 3

101. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
010305, Blast round nr. 5 is loaded
and covered by blasting mats.
Example 2, picture 1

102. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
010305, The rubber mats, covering
blast round nr. 5 are
connected by chain slings.

103. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
010305, Blast round nr 5 :
After the blast. The chain slings
have held the sheet of mats together.
Example 2, picture 3

104. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
010305, Blast round nr. 5 . The blasting mats have been removed. The blasted rock material has been held together by the blasting mats (and the right amount of explosives).
Example 2, picture 4

105. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The blast round is loaded,
the electric wires are coupled
Example 3, picture 1

106. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The blast round is covered by rubber mats,
no chain slings or wires were used in this
case to connect the mats.
Example 3, picture 2

107. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
After the blast. A good result.
one of the mats has been pushed off.
Example 3, picture 3

108. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
5.0 What help can we expect from the rubber blasting mats and other safety measures ?
For discussion :
5.1 Is it possible to stop the backbreak by means of
blasting mats when the distances between the
charge and the nearby structure are short ?
5.2 Will the use of mats help to prevent the movement
of the rock if the blast round is overloaded ?
5.3 Is it possible to stop the fragmented rock mass
when the blast round is overloaded ?
5.4 Is it possible to stop bigger pieces of flyrock
through the use of blasting mats ?

109. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
6.0 Possible damage caused by blast vibrations ?
6.1 In the case of short distances, are the blast
vibrations also a cause of the damage ?
6.2 What is the main cause of the damage -
movement of the rock mass or vibrations ?
6.3 Does an overloaded blast round mainly cause
damage through vibration or through flyrock ?
6.4 How do human beings, buildings and other
structures react when subjected to blast
vibrations ?

110. Vibration and “direct movement” of the rock mass caused by blasting :
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Vibration and “direct movement” of the rock mass caused by blasting :
In the case of distances shorter than 5 to 10 metres, “direct
movement” of the rock mass is normal the only or the main reason for the damage.
In the case of distances longer than 5 to 10 metres, high vibration
level is virtually the only reason for the damage.

111. “Direct movement of the rock” occurs owing to:
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Direct movement of the rock” occurs owing to:
Distance : mostly in the range up to 5 m.
Ground : layered rock, flaky rock, soft ground between rock and structure.
Confinement : The walls are not dug free from gravel.
Structure : Walls built of brick or blocks are not constructed to withstand powerful horizontal dynamic or static pressure.
Detonation power : When planning a blast round do not forget:  action = reaction.

112. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
BLAST VIBRATIONS This theme is described and discussed under the chapter “Bench blasting”

113. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
6.1 Blasting methods and vibration level at short distances to nearby structures.
When the blasting work is carried through in hard rock, by distances up till 5 m from the structure , the frequency in the vibration signal is normally very high (much higher than the resonance frequency of the structure).
At high frequency, higher vibration levels can be
accepted without damage.
Methods like line drilling or wire sawing
between the structure and the charges will
normally damp the vibrations to some extent.
To reduce the vibrations the use of hydraulic
spike hammers instead of drilling and blasting is
a much used alternative close to the structures.

114. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Practical job :
Method : Line drilling and blasting 7.1 Example : Line drilling by the “Notary’s house” ?

115. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The principle of the “Line drilling and blasting” method is that the holes, drilled in a line outside the wall, shall be an artificial weaknes zone. The charges in the loaded holes direct outside of the “hole line” shall not break the rock inside of the “line”.
20-35 cm
50 cm
50 cm
Unloaded drilled holes on the line
8-15 cm
Charged holes

116. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The blast direction must be alongside, not square to the
building.

117. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
The task : The rock mass should be blasted away as close as possible to the unreinforced concrete basement wall. The house was founded directly on the rock ground.

118. The method “Line drilling and blasting”
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The method “Line drilling and blasting”
By using the method of “line drilling and blasting” by “The Notary’s house” a row of holes was drilled as close to the house wall as practically possible.
The blast rounds along the wall were small, normally 6 to 8 holes.
The borehole diameter was small, 35 mm up to 2”.
The charges were small, divided into 2 or 3 decks.
Initiation started in the charge in the upper deck in the holes where the distance to the wall was the bigest.
By good planning, 5 and more blast rounds a day could be charged, covered by mats and fired.

119. 010628-2, “Notary’s house”, Line drilling 50 cm from the wall.
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
, “Notary’s house”, Line drilling cm from the wall.
The result was good. The line-drilled holes were normally not loaded. Joint sets in the rock mass which has an angle of more than 45 degrees to the wall will result in “fallouts”.

120. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
, “Notary’s house”, Line drilling square to joints works well.
The distances between the bore holes were planned to be in the same size as the diameter of the boreholes. The line-drilled holes act like an artificial weakness zone.

121. 010528-4, “Notary’s house”, Line drilling along the north wall.
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
, “Notary’s house”, Line drilling along the north wall.
It is difficult but not impossible to drill the holes straight through the joint planes. Sometimes, however, it will be necessary to use small charges in the bottom of a few line-drilled holes in cases where the holes pass through joint planes.

122. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”, Line drilling and smooth blasting at the west wall.
By a mistake, the ”line drilling” was not carried out at the southern part of the wall. The result of the blast was poor in that area.

123. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
The second blast round. Heavy rubber mats are important as protection against flyrock .

124. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
Bad fragmentation has to be accepted in this type of blasting work.

125. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
Line drilling at both ”around” the corner.

126. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
A successful blast round. The line-drilled holes act as a weakness zone.

127. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
The next blast round will cause the split to continue along the line-drilled row of holes

128. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
The splitting along the line-drilled row of holes worked well. Heavy mats were used by every blast round.

129. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
The loading process.

130. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
A blast round with only 3 holes is loaded. The electric wires are coupled together. The holes are stemmed and filled up to the top with sand.

131. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
“Notary’s house”
Fragmentation is coarse, in particular at the top of the muck pile.

132. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The charges in the holes close to the ”line drilling ” has in this case to be divided into 3 decks. 3 decks are also necessary in the second row of blast holes outside the wall. In the last two rows, two decks will sufficient. The charge in each hole and in each deck has separately to be exact calculated. Each charge in each deck in each hole must be given a separate initiation interval time.
The line-drilled holes are not loaded

133. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The distance (d) from the wall foundation to the different parts of the hole charges (Q) can be calculated separatly and used in the calculation formula. d d d

134. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Vibration
With distances from the structure to the charge in the range up to 3 m, a simple formula for the calculation of the vibration from each of the 3 or 2 charges in each deck can be used :
√Q v = k d
Q = Charge pr detonator interval (kg)
d= distance from the house to each of the divided charges (m)
k = factor for the ability of the rock to transmit vibration. With a short distance normally k = 350 or higher (calculated from vibration measurements)
v = max “allowed” vibration (mm/s). By small charges the level can be
set to 100 mm/s.

135. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The area that the charge loaded in one single hole is “responsible for” by the blast, must be calculated.
Surface area for one hole
burden
Blast direction
Spacing

136. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The top area (A) and the unit volume of the rock prism that each hole has to break, from the top of the bench to the bottom, has to be calculated. This must be done before the deck charge can be calculated. Together, this must form the basis for the specific charge in the blast round.

137. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Surfage area for one hole
The total charge in those holes which are closest to the line- drilled holes is divided into 3 separate deck charges. These 3 charges together must be sufficient to break out the calculated unit volume of rock.
50 cm dry stemming
Smooth charge 1
30 cm dry stemming h
Smooth charge 2
30 cm dry stemming
Bottom charge 3

138. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
When blasting in the area up to 3 m from the structure, the powder factor should normally be :
0.30 to 0.35 kg dynamite/cub.m. In soft rock even less.
It is however a poor precaution to use less explosive than required for the particular type of rock at the site.
If the powder factor is too low, the rock mass will not break.
 In that case the vibration at the nearby structure will rise up to 3 times higher than planned by the calculation.

139. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
There are different methods for creating a “weakness zone” or a split along one side of the building to split of the rock mass that has to be blasted from the rock mass under the nearby building structure.
Line drilling
Double line drilling
Line drilling with slotting
4) Wire sawing

140. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Eidsiva,
Line drilling and wire sawing.
An alternative to line drilling is wire sawing

141. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Eidsiva,
wire sawing.
Jointed rock, after wire sawing, will maintain the stability of the wall very well.

142. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
090111, Eidsiva power station
Detail : Line-drilled wall by using 2” drill bits.

143. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
In some cases, double line drilling and bolting has to be done before the blasting along the wall can start.

144. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Hollow for a garage
The rock outside the walls on both sides should not be disturbed.
Creating a weakness zone along the wall by sawing with a wire saw

145. Creating a weakness zone along the wall by sawing with a wire saw
European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Hollow for a garage
Creating a weakness zone along the wall by sawing with a wire saw
The horizontal and vertical holes for blowing through the saw wire are drilled, the wire
is through, the
sawing has
started.
 Saw wire

146. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Hollow for a garage
Creating a weakness zone along
the wall by sawing with wire saw
The split is sawed, the rock bolts are installed, the blasting for creating the hollow can start.
 wire sawed spalt

147. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
Hollow for a garage
Creating a weakness zone along
the wall by sawing with wire saw
The walls are sawed out, the rock is blasted out, the hollow is finished.

150. European Shotfirer Standard Education For Enhanced Mobility – ESSEEM –
The End